PRACTICAL POINTERS
FOR
PRIMARY CARE
ABSTRACTED MONTHLY FROM THE JOURNALS
OCTOBER 2004
CARDIOVASCULAR RISK FACTORS ASSOCIATED
WITH PRE-HYPERTENSION
HOW OFTEN ARE PLACEBOS USED IN PRIMARY
CARE?
POSTPRANDIAL GLUCOSE REGULATION AND
DIABETIC COMPLICATIONS.
ASPARTAME AND ITS EFFECTS ON HEALTH
DOES CHIROPRACTIC ADD TO HEALTH COSTS?
COXIBS AND CARDIOVASCULAR DISEASE: The Vioxx
Problem
BARIATRIC SURGERY: A Systematic Review
And Meta-Analysis
DO ANTIOXIDANT SUPPLEMENTS PREVENT
GASTROINTESTINAL CANCERS?
UNSATURATED FATS REDUCE RISK OF
GALLSTONE DISEASE IN MEN
PRIMARY CARE-BASED VESTIBULAR
REHABILITATION FOR CHRONIC DIZZINESS
VESTIBULAR EXERCISES FOR BALANCE
CONTROL: Easy, Inexpensive, and Effective
GASTRIC ACID-SUPPRESSIVE DRUGS
INCREASE RISK PNEUMONIA
JAMA, NEJM,
BMJ, LANCET PUBLISHED
BY PRACTICAL POINTERS, INC.
ARCHIVES
INTERNAL MEDICINE EDITED
BY RICHARD T. JAMES JR. MD
ANNALS INTERNAL MEDICINE 400
AVINGER LANE, SUITE 203
DAVIDSON NC
28036 USA
[email protected] www.practicalpointers.org
HIGHLIGHTS AND EDITORIALCOMMENTS
OCTOBER 2004
10-1
PREVALENCE OF HEART DISEASE AND STROKE RISK FACTORS IN PERSONS WITH
PRE-HYPERTENSION
Pre-hypertension
is defined as a BP of 120-139/80-89. This is considered to be above-optimal BP.
Optimal or “normal” BP is defined as under 120/80.
Persons with prehypertension have a greater risk of developing hypertension
later in life than those with lower BP.
Are persons
with prehypertension more likely to have other risk factors for stroke and
heart disease?
Compared
to patients with “normal” BP, those with prehypertension were more likely to
have an elevated cholesterol, to be overweight, and have diabetes. They were
1.7 times more likely to have at least one other risk factor compared with
normotensives. Only about ¼ of adults with prehypertension had none of the major risk factors.
The
relation between BP and cardiovascular disease risk is graded and continuous.
Appropriate prevention efforts can be initiated in persons at any level of BP
to avert development of risk factors. This extends to persons with
prehypertension.
The greater prevalence of
cardiovascular risk factors in persons with prehypertension vs normotension suggests the need for
early clinical detection and intervention. It calls for comprehensive
preventive and public health efforts.
This is an important clinical point for
primary care. It presents an
opportunity for earlier intervention and application of the most effective
preventive measures (especially lifestyle).
Primary care clinicians should check
patients with prehypertension for other risk factors: overweight/obesity, dyslipidemia, glucose intolerance and
diabetes. It is evident that attaining “normal” BP, weight, and LDL-cholesterol
does not assure the most favorable reductions in risk. Risk is graded and
continuous for all these factors. Risk
may be lowered by achieving levels below the usually quoted “normal” levels. What
are the most favorable low levels? Still to be determined.
A host of persons in the USA who have
hypertension are not aware of it. This lack of awareness must be much higher in
those with prehypertension.
10-2
QUESTIONNAIRE SURVEY ON USE OF PLACEBO
One might surmise that clinical use of placebos is rare. The deception involved in administering a placebo raises ethical questions. There is a dearth of discussion about placebos in the medical literature. Almost all citations in Medline refer to a research context. Informal discussions with clinicians indicate that use still occurs.
This study
from Israel concerned the frequency and circumstances of use of placebo in
clinical practice, and attitudes towards its use among those who administer it.
Placebos were given in the form of saline infusions, intramuscular injections,
or vitamin C tablets. They were used for anxiety, pain, agitation, vertigo,
sleep problems, asthma, contractions in labor, withdrawal from recreational
drugs.
The
majority of health care workers used placebos, some as often as once a
month. Most found them to be generally
or occasionally effective.
Ethical issues:
Only 5% thought use should be categorically prohibited. Most others
considered use conditional on circumstances such as prior experience with use,
notifying the patient that a placebo was given, or evidence from research that
the placebo was effective.
“Used wisely, placebos might have a legitimate place
in therapeutics.”
Placebos are fascinating. Over the ages,
myriads of humankind have received interventions which possess no possible
pharmacological benefits
Placebos do not cure anything. Although,
by definition, a placebo pill has no more pharmacological action than a
teaspoon of water, it may have profound psychological effects in relieving
distress. I believe relief of symptoms and lessening of anxiety in some
patients may lead to faster resolution of the illness.
We do not use placebos to treat anemia,
hypertension, or diabetes or any specific disease for which there is established
treatment. We may use them in hope of providing relief of symptoms. Indeed, a
simple (placebo) statement from the doctor may relieve considerable anxiety and
bring peace. “You will be fine, Mr. Jones.”
Response depends on the culture in which
it is presented and the enthusiasm and beliefs of the practitioner, as well as
the confidence of the recipient that it will help.
Are placebos ethical? Is their use
deceptive? Does the end justify the means? This depends on whether the
practitioner believes that there truly are benefits. It is true that placebos
have no pharmacological action. But, they may relieve symptoms even though we
do not know the mechanism. I believe placebos are a legitimate intervention in
special circumstances. They may act by providing relief and comfort while the
patient recovers naturally.
Should clinicians disclose that they are
prescribing a placebo? Would this negate benefit? We do not explain to patients how penicillin works. Indeed,
clinicians may not know the mechanism of action of many drugs they prescribe,
and certainly do not so inform the patient. For some beneficial drugs, an exact
mechanism of action may not be established. Use may depend solely on an
empirical basis. Their use is nevertheless ethical.
I do not believe clinicians should
routinely inform the patient. If she asks, however, I would not hesitate to
disclose. I believe fully informing the patient about possible benefits will be
an adequate defense. Indeed there is evidence that placebos initiate release of
endorphins.
Should clinicians charge for placebos?
This may be a more difficult decision. I believe most clinicians would be able
to include a placebo without increasing the charge for a consultation.
Although extent of use may vary between
individual clinicians, I believe use of placebos is much more prevalent than
acknowledged. We use the placebo effect every day of practice. We use vast
quantities of drugs for which there is no possible benefit. This may be the
most common use of placebos in modern clinical practice. Consider the
widespread use of antibiotics prescribed for viral infections. Would not this
be considered a placebo intervention? The prescription is given to console the
patient. Such use of drugs is becoming much more common now that advertising is
directed specifically to patients.
Should placebos be used as a diagnostic
tool? This could lead to erroneous and harmful conclusions. If the patient
obtains relief, some would say that their symptoms are not due to organic
disease. This is not true.
Do you believe the “nocebo” effect? Ie, are some interventions which have no
possible pharmacological effects associated with onset and worsening of
symptoms? (“That flu shot gave me the flu.”) If you believe the nocebo effect,
you must believe in the placebo effect.
10-3
POSTPRANDIAL GLUCOSE REGULATION AND DIABETIC COMPLICATIONS.
There is
increasing evidence that postprandial hyperglycemia is implicated in the
development of cardiovascular disease. Postprandial hyperglycemia may be
directly involved in the pathogenesis of diabetes complications through its
harmful effects on the vasculature.
Several
studies have demonstrated a striking relationship between postprandial glucose
levels and cardiovascular complications. Some have reported that 2-hour glucose
is a better predictor of complications and mortality than HbA1c or the fasting
blood glucose. The risk of death in subjects with postchallenge hyperglycemia
was reported to be almost as high as in patients with previously diagnosed type
2 diabetes.
A number of
trials have demonstrated that specific pharmacological approaches can reduce
the impact of post-prandial glycemic excursions on overall glycemic control.
The disaccharidase inhibitor acarbose (Precose)
delays the digestion of complex carbohydrates in the small bowel, and blunts
postprandial hyperglycemia. Repaglinide (Prandin),
administered immediately before meals, has pharmacological actions that make it
more attractive than sulfonylureas as an acute insulin secretogogue. It
provides a more potent effect in reducing postprandial glycemic excursions.
To achieve
normal or near-normal blood glucose levels, measurement of postprandial
hyperglycemia is essential because it not only reflects glycemic exposure
during the longest period of the day, but it may also be a required target of
diabetes management to prevent the noxious effects of hyperglycemia on the
vascular wall. Controlling postprandial glucose levels can help to optimize
metabolic control and may be particularly important for prevention of vascular
complications.
This is an
important sea-change in approach to diabetes control. It goes beyond believing
that “normal” fasting glucose and HbA1c within an “acceptable” range predict
adequate diabetes control. They do not.
It does emphasize the importance of
postprandial levels of glucose. Indeed, I believe that a 2-hour postprandial
glucose at the high range of “normal” (eg. 130) will lead to greater risk of
cardiovascular disease than a postprandial glucose of 100. I suspect there is a
linear relationship between post-prandial glucose levels and vascular disease.
This would lead incorporation of a low glycemic load diet for all persons as
part of a healthy lifestyle.
This presents a practical
application—routinely checking postprandial blood glucose in the office, noting
the time after the last meal. This would be much more convenient, and more
meaningful, than requiring the patient to come to the office fasting.
See Practical Pointers September 2004 9-3
and 9-4 for articles on relationship between glucose control and cardiovascular
disease.
10-4
ASPARTAME AND ITS EFFECTS ON HEALTH
Aspartame
(NutraSweet; Equal; Generic) consists
of two amino acids—phenylalanine and aspartic acid. Both are contained in
normal dietary proteins. Aspartame is 200 times sweeter than sucrose. The
European population consumes about 2000 tons annually as a substitute for
sugar.
Is it
harmful? The European Scientific
Committee on Food was convinced in 1988 that aspartame was safe. The committee
conducted a further review encompassing over 500 reports in 2002, It concluded
from biochemical, clinical, and behavioral research that a daily intake of up
to 40 mg/kg/day remained entirely safe—except for people with phenyketonuria.
Does
aspartame embody a healthy way of life and reduce prevalence of obesity? In
most Western countries, sugar provides about 10% of total calories (50 g daily,
or about 200 kcal). If this were entirely replaced by a non-nutritive, non-caloric
sweetner, “obesity could indeed be vanquished—assuming these calories were not
replaced”. However, evidence that
aspartame prevents weight gain or obesity is generally inconclusive.
One packet of generic aspartame contains 35 mg.
An “acceptable daily intake” = up to 3500 mg, or 100 packets, much less than
usually consumed. (Persons who drink many sweetened soft drinks daily may
approach this quantity.)
One rounded teaspoon of sucrose (5 g)
contains 20 kcal. If I added a teaspoonful of sugar to each of my 3 cups of
coffee daily in place of 3 packets of aspartime (and all other intake remained
constant) my caloric intake would increase by 60 kcal each day. By my
calculation, if I added this amount to my daily caloric intake, and assuming
perfect metabolism and conversion into fat tissue, I would gain over 5 pounds a
year.
I believe sweeteners are a reasonable
ingredient in the diet of persons who tend to be overweight and obese, and
especially in persons with diabetes. Primary care clinicians should so advise
them. Use in place of sucrose will
reduce postprandial blood glucose levels and reduce a risk factor for
cardiovascular disease.
10-5
COMPARATIVE ANALYSIS OF INDIVIDUALS WITH AND WITHOUT CHIROPRACTIC
COVERAGE.
There is
evidence supporting the efficacy of chiropractic care for back pain. A
comprehensive review reported that spinal manipulation was better, and no
trials found it significantly worse, than conventional treatment.
This
retrospective study analyzed claims data covering a 4 year period. It compared
more than 700 000 health plan members who had additional chiropractic coverage vs over 1 million members without
coverage.
Compared
with those without coverage, members with chiropractic coverage had lower annual costs (by $200). They also
had a lower average back-pain
episode-related cost.
Having
coverage was associated with a 1.6% decrease in total annual health care costs.
Back pain
patients with chiropractic coverage had lower utilization of plain radiographs and
MRI; fewer hospitalizations; less surgery and inpatient care.
Chiropractic
care sought by members with insurance coverage was more often substituted for
usual medical care. It was less often an add-on care.
Patients
treated for back pain by chiropractors tend to be more satisfied than those
treated by MDs.
The study
raises the intriguing possibility that chiropractic may in fact be the more
economic approach to the management of the complex, ill-defined, recurrent, and
often refractory symptoms of back pain.
My primary advice for a patient consulting
me for back pain would be to keep on being as active as possible. Stay out of
bed. Take acetaminophen or an NSAID temporarily. In most cases the pain will
abate spontaneously. For more protracted back pain, I would not hesitate to
refer to a chiropractor well established in the community with whom I was
personally acquainted. I would not refer for conditions other than back pain.
10-6
COXIBS AND CARDIOVASCULAR DISEASE
Recently
Vioxx (a selective COX-2 inhibitor)
was removed from the market by Merck following the results of a trial designed
to test effects on adenomatous polyp formation in the colon. The data and
safety monitoring board took action to stop the study prematurely because of a
significantly increased incidence of serious thromboembolic adverse events (vs placebo) in the group receiving 25 mg
of Vioxx daily. The incidence of
myocardial infarction and thrombotic stroke in the two groups began to diverge
after a year. FDA had approved the 3 COX-2 inhibitors on the basis of trials
that typically lasted three to six months.
In
the colon polyp study, which enrolled patients without known cardiovascular
disease, 3.5% of those receiving Vioxx
and 1.9% of those receiving placebo had a myocardial infarction or stroke. (Absolute difference = 1.6%; NNT to harm one
patient = 63.) This amounts to an
excess of 16 extra events per 1000 treated. And this was in a group with
presumably low risk.
Considering
the tens of millions of patients who were taking rofecoxib…“We are dealing with
an enormous public health issue.” “Even a fraction of a percentage excess in
the rate of serious cardiovascular events would translate into thousands of
affected persons.”
COX-2 inhibitors blunt the production of
prostaglandin I2 (a factor which protects endothelium). They do not
blunt the production of thromboxane (a risk factor for thrombosis). A single
mechanism of COX-2 inhibitors (depressing I2 while leaving thromboxane intact) might elevate BP, accelerate
atherogenesis, and predispose to thrombosis.
The higher the patient’s intrinsic risk of cardiovascular disease, the
more likely the manifestation of a clinically important adverse event.
“We now
have clear evidence of an increase in cardiovascular risk that revealed itself
in a manner consistent with a mechanistic explanation that extends to all coxibs.”
How should
clinicians respond? Selective
inhibitors of COX-2 remain a rational choice for patients at low cardiovascular
risk who have had serious gastrointestinal events, especially while taking
traditional NSAIDs.
“It would
appear prudent to avoid coxibs in patients who have cardiovascular disease, or
who are at risk for it.”
This is discouraging. Primary care
clinicians are often admonished not to prescribe a new drug until it has been
in general use for 2 or 3 years (unless it has unique benefits). Two or 3 years
of general use would presumably reveal any adverse effects not demonstrated in
trials. Now we find that, after 5 or more years of general use, Vioxx has
unreported and serious adverse effects. I suspect that more established drugs
will be discovered to have unsuspected long-term serious adverse effects. This
reinforces the old adage that “The best medicine is no medicine”.
It has long been realized that NSAIDs
increase risk of hypertension and heart failure. It appears that the risk is augmented in patients taking COX-2
inhibitors.
The FDA and the drug companies
manufacturing other COX-2 inhibitors now must conduct trials to determine
cardiovascular risk of their products as compared with placebo. Meanwhile,
primary care clinicians should be cautious about prescribing any coxib.
10-7
BARIATRIC SURGERY: A Systematic Review and Meta-Analysis
This
systematic review determined the impact of bariatric surgery on weight loss,
the effect on co-morbidities of obesity, and operative mortality.
Mean
absolute weight loss = 40 kg; mean BMI
decrease = 14. Mean percentage of excess-weight loss was 61%. In most cases,
the degree of weight loss remained the same 2 years after surgery as before.
Operative
mortality depended on the complexity of the procedure, from 0.1% for gastric
binding to 1% for bilio-pancreatic diversion and duodenal switch.
“Bariatric surgery in morbidly obese
individuals reverses, eliminates, or significantly ameliorates diabetes,
hyperlipidemia, hypertension, and obstructive sleep apnea.” It benefits the
majority of patients.
I have read that there are now more obese
individuals in the world than malnourished.
Certainly the approach to this universal
problem is not surgery. How could 8 million persons in the USA undergo surgery?
The USA needs concerted efforts to reduce obesity, this requires co-operation
between educators, food manufacturers, public health officials, and primary
care clinicians. I believe we are making some progress. It is slow.
The mean life expectancy had increased
dramatically in the USA over the past 80 years. What an even more remarkable
change would have occurred if the obesity epidemic had been prevented! RTJ
10-8
ANTIOXIDANT SUPPLEMENTS OF PREVENTION OF GASTROINTESTINAL CANCERS
“Oxidative
stress can cause cancer.” The GI tract is thought to be the major site of
antioxidant action. Many observational epidemiological studies have reported
that high intakes of fruit and vegetables (rich in antioxidants) are associated
with a lower incidence of cancer. Results of randomized trials of one or more
selected antioxidant supplements have been contradictory.
This review identified 14 randomized trials (n = 170
000 subjects) comparing antioxidants vs
placebo for prevention of GI cancers. The quality of the trials was generally
high.
The meta-analysis did not show any significant benefits of supplementation with
beta-carotene, vitamins A, C, and E (alone or in combination) vs placebo for esophageal, gastric,
colorectal, pancreatic and liver cancer.
An analysis
of 7 high-quality trials showed that antioxidants were associated with a
significantly increased
mortality. “Our result for the
detrimental effect of antioxidant supplements on mortality was unexpected.”
Four trials
(only one was high quality) reported that selenium showed significant benefit on incidence of GI cancers.
“Our systematic review contains several major
findings.” Beta-carotene, vitamin A, and vitamin E supplements given alone or
in combination do not seem to have much effect on the prevention of
gastrointestinal cancers. Further, they seem to increase overall mortality. However, 95% confidence intervals were
large in the analysis of single cancer types and could be compatible with
either beneficial or harmful effects.
Most trials have investigated the effects of
antioxidant vitamins given at substantially higher doses than those usually
found in a balanced diet, and some trials used dosages well above the
recommended upper intake levels. This might be a cause for the absence of the
expected protective effect, and for the increase in mortality associated with
high-dose antioxidant supplements.
The results should not be translated to the potential
effects of vegetables and fruits, which are rich in antioxidants. Many
substances they contain have been postulated to have anticarcinogenic
properties. Data on the effect of fruits and vegetables on cancer have been
conflicting.
Randomized
trials set up to study prevention of lung cancer showed that beta-carotene
actually increased the risk of
disease. A trial of patients at high-risk of cardiovascular disease showed no benefit after 5 years treatment with
a supplement combination. “Antioxidant supplements are not having a good
press.”
The study
found no evidence of benefit (or harm) in the combined group of 5 cancers.
However, there were 2 important exceptions: vitamin C and selenium. There was
almost no data for vitamin C used alone in cancer prevention. For selenium
there was evidence of cancer protection, although on further analysis the
benefit was confined to liver cancer.
“The
prospect that vitamin pills may not only do no good, but also may kill their
consumers is a scary speculation given the vast quantities that are used in
certain communities.” However, these results must be considered preliminary.
Nutrient
deficiency may increase risk of disease. Replacement in deficient states may
confer benefits. But for nutritionally replete individuals, excess intake may
harm.
A randomized, placebo-controlled 7-year
trial from France (Archives Int. Med. November 22, 2004) presented evidence that low-dose antioxidant
supplements reduced total cancer incidence and all-cause mortality in men but
not in women. The issue is not yet
settled. We can advise patients that as
of this date no benefit from high-dose individual vitamins has been
demonstrated for cancer prevention.
I would discourage use of high-dose
individual vitamins. I would encourage use of supplements not exceeding the
recommended daily dose.
10-9
THE EFFECT OF LONG-TERM INTAKE OF CIS UNSATURATED FATS ON THE RISK OF
GALLSTONE DISEASE IN MEN
Cholesterol gallstones have many causes.
One of the most important is hypersecretion of cholesterol into the biliary
tract. Studies report that diets high in poly-unsaturated and mono-unsaturated
fatty acids (both cis unsaturated fats) can inhibit cholesterol excretion in
the bile, and may protect against cholesterol gallstone disease.
This study
examined long-term dietary intakes of cis unsaturated fatty acids in relation
to occurrence of gallstone disease.
After
adjustment for age and other potential confounding risk factors, the relative
risk (RR) of gallstone disease among men in the highest quintile of cis
unsaturated fats compared with the lowest quintile was 0.82.
Median intake: Poly-unsaturated Mono-unsaturated
Lowest quintile Highest quintile Lowest
quintile Highest quintile
Grams per day 9.0 18 19 36
“In this large prospective study, a high intake of cis unsaturated fats was
associated with a lower risk of gallstone disease in men. ” The inverse
relationship was evident for both mono-and poly-unsaturated fat.
Cis
fatty acids have a protective effect on risk of atherosclerotic disease.
Reduction in gallstone formation may be an added attraction.
A US population study reports 800 000
hospitalizations / year due to gallstone disease. A 20% reduction would be a
major public health advance.
10-10 EFFECTIVENESS OF PRIMARY CARE-BASED
VESTIBULAR REHABILITATION FOR CHRONIC DIZZINESS
The central
element of vestibular rehabilitation (VR)
is a program of graded exercises that consists of eye, head, and body movements
designed to stimulate the vestibular systems. The simulation promotes central
compensation—neurologic adaptation to the altered input from the damaged
labyrinth. The exercises also help patients overcome fear, and to regain skill
and confidence in balance. Vestibular rehabilitation may be an effective
treatment for dizziness resulting from many causes. It is a simple therapy with no requirement for equipment. It is
highly suitable for primary care.
It is
applicable only to patients with dizziness associated with head movement.
The study
reported that, at 3 months, improvement occurred in all 5 primary outcome
measures in the VR group. Of 83 treated patients, 67% reported clinically
significant improvement compared with 38% of the usual care group; (NNT =
3). Improvement was maintained at 6
months.
The success
of VR relies on the willingness of patients to practice daily movements that
may make their symptoms worse initially. Patients should be informed of this
and that recovery may be partial. Only those who are committed should be
accepted into treatment.
“Our study provides substantive demonstration
that it is feasible to offer an effective, inexpensive treatment to patients
with dizziness in primary care.” A single brief session with a nurse was
sufficient.
This application requires an enthusiastic
mentor and a willing patient. But, this is not a reason to refrain from
recommending the procedure. RTJ
10-11 VESTIBULAR EXERCISES FOR BALANCE CONTROL:
Easy, Inexpensive, and Effective
Movement-provoked
dizziness is a typical sign of vestibular origin and therefore should respond
to vestibular rehabilitation. The response mechanism seems to be central
nervous system plasticity, a specific sensorio-motor rearrangement which can
compensate for peripheral and central neurological defects.
To
facilitate control capacities, we should expose patients to increasingly
unstable body positions. Exercise rehabilitation should begin as early as
possible, ideally immediately after symptom onset.
“This
important study strikingly demonstrates that daily vestibular exercises in the
aging population reduce symptoms, postural instability, handicaps, and falls
due to dizziness.” “These findings place the onus on primary care physicians to
put into practice such an inexpensive, simple-to-perform treatment.”
I believe other balance exercises may
benefit: eg. standing still on one foot; walking in tandem heel to toe. The objective is to fatigue an old symptom
and train a new one.
See the preceding abstract for description
of the exercises. RTJ
10-12 RISK OF COMMUNITY-ACQUIRED PNEUMONIA AND
USE OF GASTRIC ACID-SUPPRESSIVE DRUGS.
Intragastric
acid constitutes a major non-specific defense mechanism against ingested
pathogens. When the pH is under 4.0, most pathogens are promptly killed. They survive in hypochlorhydric or
achlorhydric states.
The
bacteria and viruses in a contaminated stomach in persons receiving acid-suppressing
drugs (ASD) have been identified as species from the oral cavity. This is
likely due to reduction of gastric acid leading to increased prevalence of
microbial colonization of the stomach. Microbes then backflow from the stomach
to the oral cavity, and then infect the lungs.
This study
examined the association between use of ASD and community-acquired pneumonia.
Rates of
incident pneumonia: 1) no ASD use = 0.6 per 100 person-years; 2) ASD use = 2.45
per 100
person-years. About 0.5% of patients not taking ASDs
developed pneumonia over one year vs
about 2.4% of those taking ASDs for a year.
Absolute difference = about 2% per year of administration. NNT (harm one person each year) = 50
Acid-suppressive
drugs were associated with an increased risk of community-acquired pneumonia.
This is likely a real biological effect.
I believe this is an important clinical
point especially for elderly patients, considering the large numbers of
patients taking ASDs. Primary care clinicians should be attuned to early
suspicion of pneumonia in patients taking ASDs who develop lower respiratory
symptoms.
ABSTRACTS OCTOBER 2004
Have A Greater Prevalence of Other Risk
Factors.
10-1 PREVALENCE OF HEART DISEASE AND STROKE RISK
FACTORS IN PERSONS WITH PRE-HYPERTENSION
Pre-hypertension
is defined as a BP of 120-139/80-89. This is considered to be above-optimal BP.
Optimal or “normal” BP is defined as under 120/80.
Persons with prehypertension have a greater risk of developing hypertension
later in life than those with lower BP.
This study
asked—Are persons with prehypertension more likely to have other risk factors
for stroke and heart disease?
Conclusion: They have a greater prevalence of other risk
factors.
STUDY
1. Analyzed data from over 3400 adults obtained
in 1999 and 2000 by the National Health and Nutrition Examination Survey.
2. Determined prevalence of risk
factors: total cholesterol, diabetes,
overweight, and obesity in addition to BP.
3. Compared the number or risk factors
present in persons with normotension, prehypertension, and hypertension.
RESULTS
1. Overall, roughly 1/3 of adults had hypertension,
1/3 prehypertension, and 1/3 normotension.
2. Prevalence differed considerably with age:
Normotension (%) Prehypertension
(%) Hypertension (%)
20-39 59 33 8
40-59 35 35 30
60 and above 11 23 66
3. Men had a higher prevalence of prehypertension than
women.
4. African Americans had a higher prevalence of
prehypertension than Whites and Mexican Americans.
5. Risk factors varied with BP:
Normotension (%) Prehypertension (%) Hypertension (%)
Cholesterol
over 200 42 59 71
BMI > 25 53 64 79
BMI > 30 19 31 45
Diabetes 2 4 13
6. Persons with prehypertension were 1.7
times more likely to have at least one other risk factor compared with
normotensives. Only about ¼ of adults with prehypertension had none of the major risk factors.
DISCUSSION
1. This highlights the need for early interventions to
lower BP and other risk factors through lifestyle changes.
2. Overweight/obesity was the most prevalent risk
factor.
3. The high prevalence of risk factors in
persons with prehypertension (as well as hypertension) suggests opportunities
for further preventive and public health efforts.
4. The relation between BP and
cardiovascular disease risk is graded and continuous. Appropriate prevention
efforts can be initiated in persons at any level of BP to avert development of
risk factors. This extends to persons with prehypertension.
CONCLUSION
The greater
prevalence of cardiovascular risk factors in persons with prehypertension vs normotension suggests the need for
early clinical detection and intervention. It calls for comprehensive preventive
and public health efforts.
Archives Int
Med October 25, 2004; 164: 2113-18
Original investigation, first author Kurt J Greenlund, Centers for
Disease Control and Prevention, Atlanta, GA.
See
also: “Effects of Prehypertension on
Admissions and Deaths” Archives Int Med October 25, 2004; 164:
2119-24, first author Louise B Russell, Rutgers University, New Jersey.
This original investigation reports that together, prehypertension and residual
hypertension (defined as patients with hypertension who take drugs who do not
achieve a systolic BP below 140) account for many hospital admissions, nursing
home stays, and deaths.
===============================================================================
“Used Wisely, Placebos Might Have A
Legitimate Place in Therapeutics.”
10-2 QUESTIONNAIRE SURVEY ON USE OF PLACEBO
This
small study from Israel asked—How commonly are placebos used in clinical
practice?
One might
surmise that clinical use is rare. The deception involved in administering a
placebo raises ethical questions. There is a dearth of discussion about
placebos in the medical literature. Almost all citations in Medline refer to a
research context. Informal discussions with clinicians indicate that use still
occurs.
This study
concerned the frequency and circumstances of use of placebo in clinical
practice, and attitudes towards its use among those who administer it.
Conclusion: Most practitioners used placebos. Placebos
might have a legitimate place in therapeutics.
STUDY
1. A questionnaire in hospitals and
clinics in Israel asked 31 senior hospital-based physicians, 31 head nurses,
and 27 family physicians about placebo use.
2. Main outcome = self-report of frequency and
circumstances of, and attitudes towards, use of placebo.
RESULTS
1. Among 89 respondents 60% used placebos. Among
these:
94% reported that they found placebos
generally or occasionally effective.
62% prescribed a placebo as often as once
a month.
68% told patients they were receiving
actual medication. (Deception)
28% considered placebo a diagnostic tool.
17% said nothing at all.
2. Placebos were given in the form of
saline infusions, intramuscular injections, or vitamin C tablets.
3. Placebos were used for anxiety, pain,
agitation, vertigo, sleep problems, asthma, contractions in labor, withdrawal
from recreational drugs.
4. Ethical issues: Only 5% thought use should be categorically
prohibited. Most others considered use conditional on circumstances such as
prior experience with use, notifying the patient that a placebo was given, or
evidence from research that the placebo was effective.
DISCUSSION
1. Despite general disapproval in the
medical literature, use of placebo in this population was widespread. Circumstances included a wide variety of
clinical situations.
2. Only 5 in 100 respondents would
prohibit use in all circumstances.
3, Most clinicians claimed effectiveness
of the placebo. They believed placebos can have analgesic potency.
4. Many claimed that placebos were a
diagnostic tool. But. . . “The physician who uses a placebo diagnostically is
at risk of reaching unfounded conclusions, to the detriment of his or her
patients.”
5. Some clinicians advocate banning
placebo use because of the deception involved and possible damage to the
doctor-patient relationship.
CONCLUSION
Most
practitioners in this study continued to use placebos. “Used wisely, placebos
might have a legitimate place in therapeutics.”
BMJ October 23, 2004;
329: 944-46 Original investigation,
first author Uriel Nitzan, Hadassah School of Medicine, Jerusalem, Israel.
=================================================================================
Control Postprandial Glucose to Prevent
Vascular Complications.
10-3 POSTPRANDIAL GLUCOSE REGULATION AND
DIABETIC COMPLICATIONS.
“Since
the 2-hour postchallenge level of glucose increases with age, and that of
fasting glucose does not, most cases of asymptomatic diabetes (and glucose intolerance) in the elderly
have isolated postchallenge hyperglycemia.”
There is
increasing evidence that postprandial hyperglycemia is implicated in the
development of cardiovascular disease. Postprandial hyperglycemia may be
directly involved in the pathogenesis of diabetes complications through its
harmful effects on the vasculature.
This
article provides an up-to-date review of the hypothesis that controlling
postprandial glucose levels is an important strategy in prevention of
complications of diabetes.
The
postprandial glucose level is determined by many factors: timing, quantity and composition of the
meal; carbohydrate content of the meal; and the resulting secretion of insulin
and inhibition of glucagon secretion.
Because the absorption of food continues for 5 to 6 hours after a meal,
the optimum time to measure postprandial blood glucose levels is an open
question. (I suspect it will vary between
individuals. RTJ) In general,
measurement 2 hours after a meal is practical and provides a reasonable
assessment.
Several
studies have demonstrated a striking relationship between postprandial glucose
levels and cardiovascular complications. Some have reported that 2-hour glucose
is a better predictor of complications and mortality than HbA1c or the fasting
blood glucose. The risk of death in subjects with postchallenge hyperglycemia
was reported to be almost as high as in patients with previously diagnosed type
2 diabetes.
The HbA1c
level is a useful measure of the integrated metabolic control over the
preceding 2 months. It does not reveal any information on the extent or
frequency of blood glucose excursions. One can argue that HbA1c is not the best
or most clinically useful glycemic indicator of risk of complications,
particularly at the lower end of the HbA1c range. There is no threshold of
HbA1c that will prevent vascular complications.
A number of
trials have demonstrated that specific pharmacological approaches can reduce
the impact of post-prandial glycemic excursions on overall glycemic control.
The disaccharidase inhibitor acarbose (Precose)
delays the digestion of complex carbohydrates in the small bowel, and blunts
postprandial hyperglycemia. Repaglinide (Prandin),
administered immediately before meals, has pharmacological actions that make it
a more attractive insulin secretogogue than sulfonylureas. It provides a more
potent effect in reducing postprandial glycemic excursions. The control of hyperglycemia in clinical
diabetes is an essential part of good practice. The body of evidence suggesting
a harmful effect of postprandial hyperglycemia has been sufficient to influence
guidelines from prestigious organizations. To achieve normal or near-normal
blood glucose levels, measurement of postprandial hyperglycemia is essential
because it not only reflects glycemic exposure during the longest period of the
day, but it may also be a required target of diabetes management to prevent the
noxious effects of hyperglycemia on the vascular wall. Controlling postprandial
glucose levels can help to optimize metabolic control and may be particularly
important for prevention of vascular complications.
Archives Int
Med October 25, 2004; 164: 2090-95
“Special article” review by the International Prandial Glucose (PGR)
Study Group, first author Antonio Ceriello, University of Udine, Italy.
Comment:
a Would not
small, frequent meals also relieve some of the burden of glycemia?
=========================================================================
10-4 ASPARTAME AND ITS EFFECTS ON HEALTH
Aspartame
(NeutraSweet; Equal; Generic)
consists of two amino acids—phenylalanine and aspartic acid. Both are contained
in normal dietary proteins. Aspartame is 200 times sweeter than sucrose. The
European population consumes about 2000 tons annually as a substitute for
sugar. Almost half a million tons of sucrose would be needed to generate the
same sweetness.
Is it
harmful? The internet contains a vast
catalogue of frightening personal accounts attributing multiple health
disasters to aspartame. Although no orchestrated public outcry has taken place,
much sensationalist journalism has been published. People do resent
interference with foods (eg, genetically modified foods) and regard synthetic
components with suspicion.
In contrast,
aspartame marketing implies that it embodies a healthy way of life and avoids
obesity. Evidence does not support any
link between aspartame and cancer, hair loss, depression, dementia, behavioral
disturbances, or any of the other conditions appearing in websites. (But,
proving negatives is difficult.)
Randomized controlled trials of high doses in humans have not shown any
behavioral or other adverse effects.
The
European Scientific Committee on Food was convinced in 1988 that aspartame was
safe. The committee conducted a further review encompassing over 500 reports in
2002, It concluded from biochemical, clinical, and behavioral research that a
daily intake of up to 40 mg/kg/day remained entirely safe—except for people
with phenyketonuria.
Does
aspartame embody a healthy way of life and reduce prevalence of obesity? In
most Western countries, sugar provides about 10% of total calories (50 g daily,
or about 200 kcal). If this were entirely replaced by a non-nutritive,
non-caloric sweetner, “obesity could indeed be vanquished—assuming these
calories were not replaced”. However,
evidence that aspartame prevents weight gain or obesity is generally
inconclusive. (Replacing fructose-containing soft drinks in children with
“diet’ [artificial sweetner] drinks is inversely related to weight gain.)
BMJ October 2, 2004;
329: 755-56 Editorial, first author
Michael E J Lean, University of Glasgow, Scotland.
=====================================================================
Access to Chiropractic was Associated
with Reduced Health Costs.
10-5 COMPARATIVE ANALYSIS OF INDIVIDUALS WITH
AND WITHOUT CHIROPRACTIC COVERAGE.
Back
pain accounts for billions in annual health care costs. It is a leading cause
of physician visits. It is associated with long-term disability, and is a
common cause of restricted activity and use of prescription and
non-prescription drugs.
There is
evidence supporting the efficacy of chiropractic care for back pain. A
comprehensive review reported that spinal manipulation was better, and no
trials found it significantly worse, than conventional treatment.
This study
assessed the effects of access to chiropractic care on the overall consumption
of health care. Conclusion: Access to chiropractic was associated with reduced health costs.
STUDY
1. Retrospective study analyzed claims
data covering a 4 year period. It compared more than 700 000 health plan
members who had additional chiropractic coverage vs over 1 million members without coverage.
2. Claims were primarily for lower back
pain. Other neuromusculoskeletal disorders were also included: neck pain; thoracic spine and rib disorders;
headache; upper and lower extremity myalgias and arthralgias.
RESULTS
1. Compared with those without coverage,
members with chiropractic coverage had lower
annual costs (by $200). They also had a
lower average back-pain
episode-related cost.
2, Having coverage was associated with a
1.6% decrease in total annual health care costs.
3. Patients with chiropractic coverage had
lower utilization of plain radiographs and MRI; fewer hospitalizations; less
surgery and inpatient care.
DISCUSSION
1. Back pain is a major public-health
concern. There is growing evidence for the low risks associated with
chiropractic spinal manipulation in most cases. And favorable evidence for its effectiveness in treating back
pain.
2. Chiropractic care sought by members
with insurance coverage was more often substituted for usual medical care. It was less often an add-on care.
3. Patients treated for back pain by
chiropractors tend to be more satisfied than those treated by MDs.
CONCLUSON
Access to
managed chiropractic care may reduce overall heath care expenditures. It may
prove to be clinically beneficial.
Archives Int
Med October 11, 2004; 164: 1985-92
Original investigation, first author Antonio P Legorreta, UCLA School of
Public Health, Los Angeles.
An editorial in this issue of Archives (pp 1953-54),
first author Jose Ness, University of Iowa, Iowa City comments:
Chiropractic
is certainly one to the most popular therapeutic modalities encompassed by
complementary and alternative medicine. Chiropractors are now recognized as
qualified practitioners by a growing number of health insurance companies. They
receive referrals from a considerable number of physicians practicing in other
fields of expertise. Chiropractic is now…”A profession at the crossroads of
mainstream and alternative medicine”.
The study
raises the intriguing possibility that chiropractic may in fact be the more
economic approach to the management of the complex, ill-defined, recurrent, and
often refractory symptoms of back pain.
Some in
the chiropractic profession argue for the right to be acknowledged as primary
care providers, to diagnose and treat a myriad of problems, not restricting
their practice to musculoskeletal conditions. Critical questions remain
regarding which subsets of patients could derive the most benefit from
chiropractic care. Careful scrutiny
should be applied toward defining the subset of patients who would be at a
higher risk for major complications from chiropractic and in whom intervention
would cease to be appropriate. (An important ill-defined decision primary
care clinicians must make on a basis of anecdotal evidence and judgment RTJ.)
On the
other hand, chiropractic manipulation may prove to be a safer alternative when compared with the use of NSAIDs or opiates
in frail patients.
====================================================================================
Serious Adverse Effects Uncovered After
5 Years Of General Use.
10-6 COXIBS AND CARDIOVASCULAR DISEASE
Cyclo-oxygenase 1:
COX-1 is an enzyme, continuously present, the action of which leads to ongoing formation of a prostaglandin in
many cells, including the gastric epithelium. The prostaglandin so formed
protects the gastric epithelium from ulcer formation. Inhibition of COX-1
reduces formation of the protective prostaglandin and leads to increased
tendency for formation of gastric ulcers.
Cyclo-oxygenase
2:
COX-2 is an enzyme formed intermittently in response to
inflammation. It leads to formation of a prostaglandin which mediates
inflammation. (Ie, produces fever and aching.) Selective inhibition of COX-2
reduces symptoms of inflammation while retaining the protective prostaglandin
effect on the stomach.
The
traditional NSAIDs inhibit both COX-1 and COX-2. While they benefit fever and
aching, they also are associated with an increased risk of stomach ulceration
and bleeding.
Three COX-2
inhibitors: 1) rofe-coxib (Vioxx) ,
2) cele-coxib (Celebrex) , and
valde-coxib (Bextra) , termed
“coxibs” have been available on prescription in the USA. They have been aggressively marketed
directly to the public. Sales have been in the millions. Two more coxibs are
under consideration. Coxibs are a subclass of nonsteroidal anti-inflammatory
drugs (NSAIDs) designed to selectively inhibit COX-2 (thus reducing symptoms of
inflammation) while sparing the action of COX-1 (thus maintaining the protective
effect on the stomach).
Recently Vioxx was removed from the market by
Merck following the results of a trial designed to test effects on adenomatous
polyp formation in the colon. The data and safety monitoring board took action
to stop the study prematurely because of a significantly increased incidence of
serious thromboembolic adverse events (vs
placebo) in the group receiving 25 mg of Vioxx
daily. The incidence of myocardial infarction and thrombotic stroke in the two
groups began to diverge after a year. FDA had approved the 3 coxibs on the
basis of trials that typically lasted three to six months.
Prostaglandin
I2
is the predominant cyclo-oxygenase product in endothelium. It inhibits platelet
aggregation, causes vasodilation and prevents proliferation of vascular smooth
muscle. (Ie, a protective factor.)
Suppression of I2 may remove this protective effect and lead to adverse
vascular events. It was previously assumed that prostaglandin I2 was derived
mainly by action of COX-1, and that selective COX-2 inhibitors would not lessen
its formation. This is incorrect. Both Celebrex and Vioxx, as well as traditional NSAIDs suppress the formation of
prostaglandin I2.
The effects
on prostaglandin I2 contrast with those of thromboxane. Thromboxane causes
platelet aggregation, vasoconstriction, and vascular proliferation. (I.E, a harmful factor). Aspirin and traditional NSAIDs inhibit both prostaglandin I2 and thromboxane
formation. (Ie, the adverse effects of
thromboxane are diminished as the beneficial effects of prostaglandin I2 are blunted,
somewhat canceling each other out.) It is now suggested that suppression of
COX-2, while blunting the protective effects of prostaglandin I2, may leave the
adverse effects of thromboxane intact, thus causing an increased tendency to
thrombosis.
Thus, a
single mechanism of COX-2 inhibitors (depressing I2 while leaving
thromboxane intact) might elevate BP, accelerate atherogenesis, and predispose
to thrombosis. The higher the patient’s
intrinsic risk of cardiovascular disease, the more likely the manifestation of
a clinically important adverse event.
Before the
recent Vioxx study, the benefit of
COX-2 inhibitors in protecting the stomach appeared to outweigh the adverse
cardiovascular effects. However, the study has shifted the burden of proof. “We
now have clear evidence of an increase in cardiovascular risk that revealed
itself in a manner consistent with a mechanistic explanation that extends to all coxibs.”
How should
clinicians respond? Selective inhibitors
of COX-2 remain a rational choice for patients at low cardiovascular risk who
have had serious gastrointestinal events, especially while taking traditional
NSAIDs. “It would appear prudent to
avoid coxibs in patients who have cardiovascular disease, or who are at risk
for it.”
NEJM October 21, 2004;
351: 1709-11 “Perspective”,
editorial by Garret A FitzGerald, Institute for Translational Medicine and
Therapeutics, University of Pennsylvania, Philadelphia.
See also an
editorial Failing Public
Health—Rofecoxib, Merck, and the FDA in this issue of NEJM (pp 1707-09) by
Eric J Topol, Cleveland Clinic Foundation, Cleveland Ohio.
The editorial faults both the FDA and Merck for not
heeding the many warning signs of adverse cardiovascular events which were
reported along the way. Indeed, Merck issued a relentless series of
publications reconfirming the favorable cardiovascular safety of Vioxx. One study comparing naproxin with
Vioxx reported an increase in cardiovascular events from Vioxx vs naproxin. But, the study
suggested that the difference was due to a protective effect of naproxin, not
an adverse effect of Vioxx.
In the
colon polyp study, which enrolled patients without known cardiovascular
disease, 3.5% of those receiving Vioxx
and 1.9% of those receiving placebo had a myocardial infarction or stroke. (Absolute difference = 1.6%; NNT to harm one
patient = 63.) This amounts to an
excess of 16 extra events per 1000 treated. And this was in a group with presumably
low risk.
Considering
the tens of millions of patients who were taking rofecoxib. . . “We are dealing
with an enormous public health issue.”
“Even a fraction of a percentage excess in the rate of serious
cardiovascular events would translate into thousands of affected persons.”
===========================================================================================
Significantly Ameliorates Diabetes,
Hyperlipidemia, Hypertension, and Obstructive Sleep Apnea.
10-7 BARIATRIC SURGERY: A Systematic Review and
Meta-Analysis
The world
epidemic of overweight (BMI > 25) and obesity (BMI > 30) is estimated to
encompass 1.7 billion individuals. About 2/3 of individuals living in the USA
are overweight, and, of these, almost half are obese. An estimated 23 million
individuals in the USA have a BMI over 35;
8 million have a BMI over 40.
The
associated co-morbidities are legion and are responsible for over 2 million
deaths per year and loss of life span of 12 years.
Diet
therapy, with or without support organizations, is relatively ineffective
long-term. Currently there are no truly effective pharmaceutical agents
available to treat obesity, especially morbid obesity. Morbid obesity is
defined as a BMI > 40 (or BMI > 35 in the presence of significant co-morbidities).
The NIH has established guidelines for surgical treatment (bariatric surgery).
This
systematic review determined the impact of bariatric surgery on weight loss,
the effect on co-morbidities of obesity, and operative mortality.
Conclusion: Surgery achieved effective weight loss and
greatly reduced co-morbidity.
STUDY
1. Reviewed 136 bariatric surgery studies
(total of over 20 000 patients; 73% women). Mean age = 39. Baseline BMI = 47,
highest 69 (morbid obesity).
2. Analyzed effects of 4 different
surgical interventions.
RESULTS
1. Mean absolute weight loss = 40 kg; mean
BMI decrease = 14. Mean percentage of excess-weight loss was 61%. In most cases, the degree of weight loss
remained the same 2 years after surgery as before.
2. Operative mortality depended on the
complexity of the procedure, from 0.1% for gastric binding to 1% for
bilio-pancreatic diversion and duodenal switch.
3. Diabetes was “completely resolved” in
77% (defined as ability to discontinue all diabetes-related drugs and maintain
blood glucose within normal range).
4. Hyperlipidemia improved in 70%.
5. Hypertension resolved in 62%
6. Sleep apnea resolved in 86%. “Improvement in sleep apnea was dramatic.”
DISCUSSION
1. “Bariatric surgery in morbidly obese
individuals reverses, eliminates, or significantly ameliorates diabetes,
hyperlipidemia, hypertension, and obstructive sleep apnea.” It benefits the
majority of patients.
2. Resolution of diabetes often occurred
in days following surgery, even before weight loss.
3. A recent randomized study from Sweden
reported that, after 2 years, the incidence of hyperlipidemia was lower by
10-fold in the surgical group vs
controls. Of subjects with diabetes, the annual mortality rate was decreased by
80%
4. Benefits in reducing the adverse social
effects of obesity are considerable.
CONCLUSION
In addition
to achieving effective weight loss, bariatric surgery led to resolution of
diabetes, hypertension, hyperlipidemia, and obstructive sleep apnea in a
substantial majority of patients.
JAMA October 13, 2004;
292: 1724-37 Systematic review,
first author Henry Buchwald, University of Minnesota, Minneapolis.
================================================================================
The Bloom Seems to be Coming Off the
“Antioxidant” Theory.
10-8 ANTIOXIDANT SUPPLEMENTS OF PREVENTION OF
GASTROINTESTINAL CANCERS
“Oxidative
stress can cause cancer.” The GI tract is thought to be the major site of
antioxidant action. Many observational epidemiological studies have reported
that high intakes of fruit and vegetables (rich in antioxidants) are associated
with a lower incidence of cancer. Results of randomized trials of one or more
selected antioxidant supplements have been contradictory.
This systematic
review and meta-analysis aimed to establish whether high-dose antioxidant
supplements reduce the incidence of GI cancer and mortality.
Conclusion: No evidence that high-dose supplements
prevent cancer. Some evidence that they may increase
overall mortality
STUDY
1. The review identified 14 randomized trials (n = 170
000 subjects) comparing antioxidants vs
placebo for prevention of GI cancers. The quality of the trials was generally
high.
2. Supplements were given daily by mouth.
Doses Usual
daily supplement dose:
Beta-carotene 15
to 50 mg 6 mg
Vitamin A 1.5
to 15 mg 1 mg
Vitamin C 120
to 2000 mg 60 mg
Vitamin E 30
to 600 mg 15 mg
Selenium 50
to 228 ug. 70 ug
(The mean of these doses exceeded the recommended
daily dose and the usual supplement dose.)
3. Outcome measures
= incidence of GI cancers and overall mortality.
RESULTS
1. The meta-analysis did not show any significant benefits of
supplementation with high-dose beta-carotene, vitamins A, C, and E (alone or in combination) vs placebo for esophageal, gastric,
colorectal, pancreatic or liver cancer.
2. An analysis of 7 high-quality trials
showed that antioxidants were associated with a significantly increased mortality.
3. Four trials (only one was high quality)
reported that selenium showed significant benefit
on incidence of GI cancers.
DISCUSSION
1. “Our systematic review contains several
major findings.” Beta-carotene, vitamin
A, and vitamin E supplements given alone or in combination do not seem to have
much effect on the prevention of gastrointestinal cancers. Further, they seem to increase overall mortality. However, 95% confidence intervals were
large in the analysis of single cancer types and could be compatible with
either beneficial or harmful effects.
2. Most trials have investigated the
effects of antioxidant vitamins given at substantially higher doses than those
usually found in a balanced diet, and some trials used dosages well above the
recommended upper intake levels. This
might be a cause for the absence of the expected protective effect, and for the
increase in mortality associated with
high-dose antioxidant supplements. “Our result for the detrimental effect of
antioxidant supplements on mortality was unexpected.”
3. A recent study suggested that
beta-carotene might act as a co-carcinogen.
4. The study also identified seven
randomized trials that assessed antioxidant supplements in the primary or
secondary prevention of colo-rectal adenomas. The pooled effect of all trials
was not statistically significant.
5. Use of antioxidant supplements in the
USA has increased substantially. More than half of women in the Women’s Health
Initiative took antioxidant supplements in some form.
6. If the mortality findings are correct,
the number needed to treat to harm one patient = 112. For every million people
exposed, about 9000 premature deaths could have occurred.
7. The results should not be translated to
the potential effects of vegetables and fruits, which are rich in antioxidants.
Many substances they contain have been postulated to have anticarcinogenic
properties. Data on the effect of fruits and vegetables on cancer have been
conflicting.
8. The US Preventive Task Force considers
that antioxidant supplements might not
be beneficial for cancer prevention.
CONCLUSION
“We could
not find evidence that antioxidant supplements prevent gastrointestinal
cancers; on the contrary, they seem to increase overall mortality.”
Lancet October 2,
2004; 1219-28 Original investigation,
first author Goran Bjlakovic, Copenhagen University Hospital, Denmark.
Comment:
Vitamin
A is a generic term for compounds that exhibit the biological properties of
retinol (a chemical entity).
Beta-carotene
is a plant pigment consisting of 2 molecules of retinol joined in a chain.
An
editorial in this issue of Lancet (pp 1193-94), first author David Forman, University of Leeds, Leeds, UK
comments on the study:
“Antioxidant supplements are not having a good press.”
Randomized trials set up to study prevention of lung cancer showed that
beta-carotene actually increased the
risk of disease.
A trial of
patients at high-risk of cardiovascular disease showed no benefit after 5 years treatment with a supplement combination.
The study
found no evidence of benefit (or harm) in the combined group of 5 cancers.
However, there were 2 important exceptions: vitamin C and selenium. There was
almost no data for vitamin C used alone in cancer prevention. For selenium
there was evidence of cancer protection, although on further analysis the
benefit was confined to liver cancer.
“The
prospect that vitamin pills may not only do no good, but also may kill their
consumers is a scary speculation given the vast quantities that are used in
certain communities.” However, these results must be considered preliminary.
==========================================================================================
A High Intake of cis Fatty Acids was
Associated with a Reduced Risk Of Gallstone Disease
10-9 THE EFFECT OF LONG-TERM INTAKE OF CIS
UNSATURATED FATS ON THE RISK OF GALLSTONE DISEASE IN MEN
Cholesterol
gallstones have many causes. One of the most important is hypersecretion of
cholesterol into the biliary tract. Studies report that diets high in poly-unsaturated
and mono-unsaturated fatty acids (both cis unsaturated fats) can inhibit
cholesterol excretion in the bile, and may protect against cholesterol
gallstone disease. This study examined
long-term dietary intakes of cis unsaturated fatty acids in relation to
occurrence of gallstone disease.
Conclusion: A high intake of cis unsaturated fats was
associated with a reduced risk of gallstone disease in men.
STUDY
1. Beginning in 1986,
the Health Professionals Follow-up Study
followed over 45 000 men ages 40 to 75. All were free of gallstone disease at
baseline.
2. Periodically
determined intake of unsaturated fats as part of a 131-item semi-quantitative
food- frequency questionnaire.
3. Main outcome =
self-reported newly diagnosed symptomatic gallstone disease related to cis
unsaturated fat intake. Follow-up = 14 years.
RESULTS
1. Documented 2323 new
cases of gallstone disease over the follow-up period. Outcomes were restricted to men with cholecystectomy and
diagnostically confirmed but unremoved symptomatic gallstones.
2. After adjustment for
age and other potential confounding risk factors, the relative risk (RR) of
gallstone disease among men in the highest quintile of cis unsaturated fats
compared with the lowest quintile was 0.82.
RR (highest quintile vs lowest) of intake
of mono-unsaturated fats = 0.83
RR (highest quintile vs lowest) of intake
of poly-unsaturated fats = 0.84
3. Median intake: Poly-unsaturated Mono-unsaturated
Lowest quintile Highest quintile Lowest
quintile Highest quintile
Grams per day 9.0 18 19 36
(Ie, the median intake varied by about
2-fold between lowest and highest.)
DISCUSSION
1. “In this large prospective study, a
high intake of cis unsaturated fats was associated with a lower risk of
gallstone disease in men.” The inverse relationship was evident for both
mono-and poly-unsaturated fat.
2. There was an inverse relationship
between intakes of linoleic acid and oleic acid, the predominant cis
unsaturated fats in the US diet. Addition of palmitic acid (a saturated fat)
enhanced cholesterol gallstone formation.
3. In animal experiments, substitution of
olive oil or corn oil for butter prevented gallstone formation. This may have
been due to effects on stabilization of bile-excreted cholesterol.
4. In addition, intake of mono- and
poly-unsaturated fatty acids can improve insulin sensitivity. Gallstone disease
is thought to be one manifestation of the insulin-resistance syndrome. (The
“metabolic syndrome”.) Hyperinsulinemia
has been linked to enhanced hepatic synthesis of new cholesterol and increased
excretion of cholesterol in the bile and may enhance cholesterol gallstone
formation.
5. Epidemiologic and clinical studies have
reported a lower incidence of gallstones in populations consuming higher
amounts of cis acids. (However, results have been somewhat conflicting.)
6. Silent gallstones were not included in
the study. The results may underestimate the prevalence of gallstones.
CONCLUSION
A high
intake of cis fatty acids was associated with a reduced risk of gallstone
disease in men.
Annals Int Med
October 5 2004; 141: 514-22
Original investigation, first author Chung-Jyi Tsai, Harvard Medical
School, Boston, Mass.
The article included a glossary:
Cis (unsaturated) fatty acids:
1) Mono-unsaturated: At only one point along the
carbon backbone, 2 carbon atoms are connected by a single double-bond. (Eg,
olive oil, peanut oil, most nuts)
2) Poly-unsaturated: Two or more double bonds. (Eg,
vegetable oils [safflower, corn, canola], fatty fish.)
Subdivided into: 1) n-3 and n-6 groups
depending on the distance of the first double bond from the CH3 end.
Saturated fatty acids:
Completely saturated
with hydrogen atoms. No double bonds. (Eg coconut oil, palm oil, meats,
poultry, and dairy products.)
Trans fatty acids:
Formed through partial hydrogenation of
unsaturated oils. This changes oils to solids.
==================================================================================
Vestibular Rehabilitation Exercises May
Be an Effective Treatment for Dizziness
10-10 EFFECTIVENESS OF PRIMARY CARE-BASED
VESTIBULAR REHABILITATION FOR CHRONIC DIZZINESS
Dizziness
is a very common symptom in the general population.. It is associated with
falls, fear of falling, and loss of independence in older people. It may lead
to substantial disability.
The most
common cause of dizziness presenting to primary care is a peripheral vestibular
disorder. Psychiatric factors are also common causes. Serious cardiovascular or
neurological disease is not common. A multifactorial syndrome is common in
older people.
No
medication in current use has well-established curative or prophylactic value
or is suitable for long-term palliative use.
The central
element of vestibular rehabilitation (VR)
is a program of graded exercises that consists of eye, head, and body movements
designed to stimulate the vestibular systems. The simulation promotes central
compensation—neurologic adaptation to the altered input from the damaged labyrinth.
The exercises also help patients overcome fear, and to regain skill and
confidence in balance. Vestibular rehabilitation may be an effective treatment
for dizziness resulting from peripheral vestibular disorder, benign positional
vertigo, anxiety, multifactorial dizziness in the elderly, and head injury. It
is a simple therapy with no requirement for equipment. It is highly suitable
for primary care.
This study
evaluated the effectiveness of nurse-delivered VR for patients with chronic
dizziness.
Conclusion: Vestibular rehabilitation improved symptoms,
postural stability, and dizziness-related handicap.
STUDY
1. A single-blind randomized, controlled
trial in 20 general practices entered 170 adult patients with chronic
dizziness. Mean age = 62; duration of symptoms averaged 8 years. At baseline
all patients had dizziness provoked by head movement.
2. The exercises served as a screening
test to identify patients with movement-provoked dizziness which is typical of
vestibular imbalance and therefore should respond to VR. The most common
diagnoses recorded by the primary care clinician were dizziness of unknown
cause and vertigo of unknown cause. Benign positional vertigo was reported in
only 9 patients.a
3. Randomized to: 1) vestibular rehabilitation, or 2) usual
medical care. At the end of 3 months, the usual-care group crossed over and
received VR. Patients adapted the exercise program to suit their symptoms,
capabilities, and lifestyle.
4. Each patient assigned to VR received
one 30- to 40- minute appointment with a primary care nurse. The nurse taught
the patient exercises to be carried out daily at home, with the support of a
treatment booklet. The set of head and eye exercises consists of repeatedly
moving the head as far and as fast as comfortably possible, first from left to
right, and then up and down with eyes open, with fixation and then without
fixation; and then with eyes closed. Exercises were repeated several times
every day—beginning slowly while sitting and then progressing as individually
possible to a more rapid rate while standing and walking. Continued for 3
months, or until dizziness was no longer provoked by any movement.
5. Measured outcomes at 3-months and 6-months by self-reported symptoms of dizziness, dizziness-related quality-of-life, and by objective measurement of postural stability.
6. Primary outcome = self-reported
spontaneous and provoked symptoms of dizziness, dizziness-related
quality-of-life, and objective measurements of postural stability Five outcome
measures = vertigo symptom scale, movement-provoked dizziness, postural
stability eyes open, postural stability eyes closed, and dizziness handicap
inventory.
RESULTS
1. At baseline, all
participants had symptoms provoked by head movement.
2. At 3 months,
improvement occurred in all 5 primary outcome measures in the VR group. Of 83
treated patients, 67% reported clinically significant improvement compared with
38% of the usual care group; (NNT = 3).
Improvement was maintained at 6 months.
3. At 3-months, 23% in
the VR group had no provoked symptoms vs
6% in the usual care group. (NNT = 6)
4. Between 3 and 6
months, the VR group maintained their improvement. (No significant
deterioration.)
5. The usual care group
received VR during the second 3 months. They improved significantly during this
time. No difference between groups at 6 months.
6. Self-reported
adherence was fair—71% reported carrying out the exercises most days of the
week. But only 55% continued with the exercises for at least 2 months or until
the symptoms ceased.b
7. No serious medical
problems related to the VR were reported.
DISCUSSION
1. VR introduced and supervised by nurses
can reduce symptoms, disability, and handicap resulting from chronic dizziness.
2. Outcomes were based on subjective
reports. Reported improvement could be due to nonspecific psychological
effects. However, the results are consistent with a specific treatment effect.
3. The success of VR relies on the
willingness of patients to practice daily movements that may make their symptoms
worse initially. Patients should be informed of this and that recovery may be
partial. Only those who are committed should be accepted into treatment.
4. “Our study provides substantive
demonstration that it is feasible to offer an effective, inexpensive treatment
to patients with dizziness in primary care.” A single brief session with a
nurse was sufficient.
Annals Int Med
October 18, 2004; 141: 598-605
Original investigation, first author Lucy Yardley, University of
Southampton, UK.
Comment:
a I believe
benign positional vertigo is much more common in primary care. A different type
of VR may be useful.
b I believe
fewer patients in primary care will comply. This application requires an
enthusiastic mentor and a willing patient.
But, this is not a reason to refrain from recommending the procedure.
=================================================================================
10-11 VESTIBULAR EXERCISES FOR BALANCE CONTROL:
Easy, Inexpensive, and Effective
(This
editorial comments and expands on the preceding study.)
Dizziness
and vertigo are related to many physiological and pathologic processes. There
are many types: vestibular rotational vertigo syndromes with nausea and
vomiting, visual vertigo, presyncopal light-headedness, hypoglycemia, drug
intoxication, phobias, panic attacks, physiological motion sickness, and height
vertigo. Although prophylaxis and treatments differ depending on cause,
physical therapy for balance control is common to all.
Balance
control is one of the key functions of the vestibular system. The vestibular
system, together with the visual and somatosensory systems, promotes spatial
orientation, locomotion, and control of posture.
Overlapping
functions of different sensory systems allow one sense to substitute, at least
in part, for deficiencies in the others.
Movement-provoked
dizziness is a typical sign of vestibular origin and therefore should respond
to vestibular rehabilitation. The response mechanism seems to be central
nervous system plasticity, a specific sensorio-motor rearrangement which can
compensate for peripheral and central neurological defects.
To facilitate
control capacities, we should expose patients to increasingly unstable body
positions. Exercise rehabilitation should begin as early as possible, ideally
immediately after symptom onset.
“This
important study strikingly demonstrates that daily vestibular exercises in the
aging population reduces symptoms, postural instability, handicaps, and falls
due to dizziness.” “These findings place the onus on primary care physicians to
put into practice such an inexpensive, simple-to-perform treatment.”
Annals Int Med
October 19, 2004; 141: 641-43
Editorial by Marianne Deiterich, Johannes-Gutenberg University, Mainz,
Germany.
=============================================================================
10-12 RISK OF COMMUNITY-ACQUIRED PNEUMONIA AND
USE OF GASTRIC ACID-SUPPRESSIVE DRUGS.
Intragastric
acid constitutes a major non-specific defense mechanism against ingested
pathogens. When the pH is under 4.0, most pathogens are promptly killed. They survive in hypochlorhydric or
achlorhydric states.
For
effective management of upper gastrointestinal symptoms, the intragastric pH
should be maintained above 4.0 for at least 18 hours daily. Acid suppression
may lead to impaired elimination of pathogens and increased colonization.
The
bacteria and viruses in a contaminated stomach have been identified as species
from the oral cavity.
This study
examined the association between use of acid-suppressing drugs (ASD) and community-acquired pneumonia.
(CAP)
Conclusion: Current use of ASD was associated with an
increased risk of CAP.
STUDY
1. Identified use of ASDs in about 150
primary care practices. This included over 350 000 individuals whose records
over 8 years were availably electronically.
2. Determined use of proton pump
inhibitors and H2 blockers, and duration of use. Determined the first
occurrence of pneumonia.
3 Conducted a case-control analysis: 1)
Cases = individuals with incident pneumonia during or after stopping use of
ASD; 2) Controls = individuals not using ASD matched for each case of
pneumonia.
RESULTS
1. Documented over 5500 first-occurrences
of community-acquired pneumonia.
2. Rates of incident pneumonia: 1) no ASD use = 0.6 per 100
person-years; 2) ASD use = 2.45 per 100
person-years.
3. Relative risks for community-acquired pneumonia:
Unexposed to ASD Exposed
to ASD
No. of patients 345
000 19 000
No. of cases of pneumonia 5366 185
Relative risk 1.00 4.5
4. About 0.5% of
patients not taking ASDs developed pneumonia over one year vs about 2.4% of those taking ASDs for a year. Absolute difference = about 2% per year of
administration.
5. Adjusted relative
risk for pneumonia among current users of ASD compared with those who had
stopped use = 1.63.
6. Risk was higher in
those taking proton-pump inhibitors compared with H2-receptor blockers.
7. Current use was more
risky than use over 30 days prior.
8. There was a clear dose-response relationship.
DISCUSSION
1. In this large cohort, current use of
ASDs was associated with an increased risk of community-acquired
pneumonia. This is likely a real
biological effect.
2. As long ago as 1934, a study suggested
that bacillary and amoebic dysentery occurred much more frequently in subjects
with hypochlorhydria or achlorhydria.
3. Studies in mechanically ventilated
patients support the results. In these patients use of ASDs is associated with
colonization of the oral space via the stomach. The colonized microbes in the
stomach gain access to the oral cavity and on to the lower airways causing
lower respiratory infection. Backflow of gastric contents into the esophagus
because of an incompetent barrier at the gastro-esophageal junction is common.
4. The investigators believe the results,
although observational, are generalizable to the general population.
5. Elderly patients are likely to incur
severe infection, partly due to an impaired immune response and the natural
reduction of gastric acid secretion.
CONCLUSION
Acid-suppressive
drugs were associated with an increased risk of community-acquired pneumonia.
This is likely due to reduction of gastric acid leading to increased prevalence
of microbial colonization of the stomach. Backflow into the oral cavity and
then to the lungs follows.
JAMA October 2004; 292:
1955-60 Original investigation,
first author Robert J F Laheij, University Medical Center St. Radboud, Nijmegen
Netherlands.
===============================================================================