SURGERY FOR WEIGHT LOSS: COMPARISON OF RISK AND BENEFIT
by Paul Ernsberger, Ph.D.
"Well, the gold standard in
medicine is the controlled clinical trial. We don't go subjecting 100,000 people
to a surgical procedure without doing a controlled clinical trial or dozens of
clinical trials, and then looking at the results. Do you know how many clinical
trials have been published on weight-loss surgery or gastric bypass? Zero. None
of them have compared it to clinical conservative treatment and found it to be
superior for life expectancy or for anything else other than, you know, risk
factors. A number of trials have been started, and the final results have never
been reported. We have to ask, you know, why haven't we seen the final results?
I think it's because it's bad news. "
(Paul Ernsberger on Donahue, 2002)
from Obesity & Health (renamed Healthy Weight
Journal)
March-April 1991, pp. 24-25
As the eve of the 1991 NIH consensus conference on weight-loss surgery
approaches, let us look back at the last NIH conference on this topic in
December 1978. The panel gave its approval to intestinal bypass surgery, even
though this operation was already coming under criticism for the long-term
side-effects that it caused. As a result of recommendations by the consensus
panel, intestinal bypass was accepted for health insurance coverage, which made
possible tens of thousands of these operations. The legacy of the NIH panel's
endorsement of intestinal bypass surgery is perhaps a hundred thousand patients
worldwide, the majority of whom have suffered severe complications. Of the
survivors, most now have had the operation undone. One can only hope that the
legacy of this latest panel is more benign.
The panel members face a difficult task in evaluating the risks of the
various surgical treatments for obesity. Nearly very surgical operation
originates in a laboratory, where it is refined by extensive tests in animals.
For example, coronary bypass surgery was the product of years of experimentation
on dogs in which repeated measurements and detailed autopsies revealed potential
complications and allowed surgeons to perfect the operation. In contrast, only
three animal tests have ever been reported or gastric bypass or gastroplasty. In
one test of gastric bypass in rats, many abnormalities were found at autopsy,
including damage to the stomach, liver and pancreas from fibrosis (American
Journal of Clinical Nutrition 40:293-302, 1984). We don't know whether these
progressive abnormalities happen in human patients, because autopsy results have
never been reported. Because of a lack of animal testing, the panelists will
lack information on the biological effects of these operations.
Another difficulty the panelists will face is the bewildering variety of
operations. As many as two dozen basic types of both gastroplasty and gastric
bypass are in current use, along with several modifications of the original
intestinal bypass. If we then consider variations on the basic methods, it can
almost be said that no two surgeons do exactly the same procedure. The different
types of operations differ in their safety and effectiveness. Operations such as
gastric bypass that impair the absorption and processing of nutrients produce
the greatest weight loss, and are most likely to produce lasting weight loss.
With gastroplasty, weight regain is more common. After the most effective
operation of this type, the vertical banded gastroplasty, 76% of patients failed
to maintain weight loss after 30 months of follow-up (Surgery 98:700-707, 1985).
In another study, 69% had fair-to-poor results in maintaining weight loss after
23 months and 22% suffered from obstruction of the narrow outlet from the
stomach pouch (Mayo Clinic Proceedings 61:287-291, 1986). Weight regain after
gastroplasty is usually the result of gradual stretching and enlargement of the
stomach pouch or the narrow outlet from it. Because the stomach is almost
infinitely expandable and adapts to increased pressure by growing larger, the
operation is doomed to be eventually undone by natural adaptive processes of the
patients' body. Although gastric bypass is more effective in maintaining loss of
weight, there are more long-term complications, particularly nutritional
deficiencies including anemia, pernicious anemia, osteoporosis, and neurological
damage. These same complications were described 30 years ago as the long-term
result of stomach surgery for ulcers. Consequently, these operations were long
ago abandoned for treatment of ulcer.
The stomach is not simply passive sac for
storing ingested food, but plays a complex role in the processing of nutrients.
Surgical procedures which interfere with the normal operation of the stomach
inevitably cause multiple problems. Unfortunately, no controlled trials have
ever been run which include physical examination of the patients for possible
side effects by independent doctors not associated with the surgeon. In a rare
instance of independent examination of bariatric surgery patient, a team of
neurologists examined 500 patients who had received either gastric bypass or
gastroplasty and found neurological complications (nerve or brain damage) in 5%
of them (Neurology 37:196-200, 1987). The patients were usually examined within
a year after surgery, so the incidence of long-term neurological deterioration
could be much higher than 5%. Possible damage to organs other than brain and
nervous system has not been put under rigorous independent evaluation.
Once a surgical technique has been developed in the animal laboratory,
normally the next step is to run controlled clinical trials comparing long-term
outcomes for patients and an untreated control group. Coronary bypass was tested
in this way and it was proven that heart patients undergoing surgery lived
longer than comparable patients getting only non-surgical treatment. No
controlled clinical trials have ever been run for weight-loss surgery, except
for one Danish trial of gastric bypass that showed that patients undergoing
surgery experienced more health problems than comparable patients who were put
on very-low-calorie diets (New England Journal of Medicine 310:352-356, 1984;
Danish Medical Bulletin 37:359-370, 1990). Gastric bypass or gastroplasty does
result in improved levels of blood pressure. cholesterol, and blood sugar. These
reduced risk factors might translate into long-term disease prevention over the
patients' lifespan if (and only if) their reduced weight can be maintained for
life.
Do the benefits of weight loss exceed the risks of major surgery and the
side-effects of tampering with the digestive system? In considering this
question, the consensus panel must first ask whether weight loss is permanent.
If a patient loses 100 pounds only to gain it back five years later, then her
risk factors will return to dangerous levels. Because of the harmful effects of
losing and regaining weight (the "yo-yo syndrome"), some risk factors,
especially blood pressure, may be worse after regain of weight than they were at
the start. When the risks of surgery and long-term complications are taken into
account, then it become apparent that the net outcome for the patient who
regains weight is highly negative. The typical patient receiving these
operations is a woman in her 30's. To be certain of reducing her risk for heart
disease later in life, weight loss must be assured for at least 10 years and
preferably 20.
The consensus panel must also consider the benefit side of the risk-benefit
equation. In order to evaluate the benefits of weight loss in extremely obese
persons, let us start with the assumption that the poor health suffered by fat
people can be completely reversed by weight loss. This may not be a valid
assumption, especially because it is now dear that many fat people are burdened
by a genetic defect that allows runaway weight gain. This same genetic defect
may also lead to diabetes, high blood pressure and heart disease. Currently we
do not know whether the health problems of the obese are directly caused by the
fatty deposits themselves or whether they result from defective genetic
machinery. If the latter is true, then weight loss will not completely erase the
excess risk associated with obesity, because weight loss will not change a
person's genetic makeup. Setting this argument aside, let us consider the actual
risk faced by extremely obese persons. The median life expectancy from age 25 as
a function of body mass index is shown in the illustration above (see original
article). These data were taken from the world's largest epidemiological study,
which tracked 1.8 million Norwegians for 10 years (Acta Medica Scandinavica
Supplementum 679:1-56, 1984). Let us consider the lifespan of women, since
90-95% of all patients undergoing weight-loss surgery are female. Women who are
neither underweight nor overweight have a life expectancy of about 79 years.
Morbid obesity begins at a body mass index of 35. Women with a body mass index
of 40 and above are shown at the far right. Their life expectancy is reduced by
5 years, which is equivalent in risk to light cigarette smoking. However, even
these extremely obese women still have a longer life expectancy that
normal-weight men. Several conclusions can be made from this graph: first, the
typical "morbidly obese" woman in her 30's considering weight-loss surgery faces
another four decades of life, which means that weight loss maintenance and
surgical complications must be evaluated over the very long term. Second, given
that the maximum benefit from weight-loss is a 5-year prolongation of life, the
risks from surgery must be kept very low. Third, surgery should clearly be
reserved for the most obese patients (body mass index over 40) and the ongoing
trend for surgeons to make exceptions to the "100-pound rule" and operate on
thinner patients must be deplored.
The challenge awaiting the NIH consensus panel is formidable. They will lack
a base of knowledge of the biological effects and the medical consequences of
these operations, especially over the long term. The vast array of variations of
these operations complicates any evaluation. Operations that are more effective
are also less safe; none of the surgical procedures seem to be both safe and
effective. Risks and benefits must be compared over the remaining 40 years of
life expectancy of the patient, but for many procedures patients are tracked for
two years or less, and many times only weight loss is recorded without
independent evaluations of the patients' overall health. Hopefully the 1991
panel will not repeat the mistakes of the 1978 panel, which failed to confront
the epidemic of complications from intestinal bypass.
Paul Ernsberger, Ph.D.
Associate Professor of Medicine, Pharmacology
and Neuroscience
Case Western Reserve School of Medicine
10900 Euclid
Avenue
Cleveland, OH 44106-4982
pre@po.cwru.edu
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