Cardiovascular System in Obesity: Effect of Treatment

BACKGROUND:

Obesity is a problem of significant public health concern both in this and other western countries. One reason is that it is a risk factor for cardiovascular disease, most notably hypertension. For example, in the Framingham study it was found that relative body weight, weight change during observation, and skin fold thickness were related to existing blood pressure levels and to the subsequent rate of development of hypertension. Additionally, for previously normotensive individuals, the risk of developing hypertension was proportional to the degree of overweight. Obesity is also a major risk factor for type II diabetes mellitus. On the other hand, some overweight individuals are physically healthy but suffer from the psychosocial consequences of their condition so that losing weight would be desirable for them as well as for individuals more at risk for physical illness.

Like essential hypertension, obesity is not only a chronic condition for many individuals but it is also a heterogeneous condition with many underlying causes and interacting factors. It is generally difficult to treat because it is a chronic problem, success comes slowly, and physicians in practice generally understand the condition rather poorly and do not manage it well. Results from studies of caloric restriction, behavior modification and medication have often been disappointing both to the subjects and their physicians. In practice, dropout rates from exercise programs, as well as various dietary self-help programs have been relatively high.

Similarly, in clinical trials dropout rates have often been quite high. Compounding the problem of weight management has been a rather universal negative bias on the part of physicians to prescribing anorexiant medications. It was previously generally held that these agents were either only effective in the short term or not at all. Additionally, there has always been concern about the potential adverse effects of anorexiants as well as their potential for abuse. Physicians who used appetite suppressants often prescribed them for only four to six weeks which was inappropriate in the management of a chronic condition.

In several relatively short term clinical trials (e.g., 16 weeks), it has been shown that appetite control medications such as fenfluramine and phentermine were more effective than placebo in inducing weight loss. It has been less clear from the trials performed heretofore how effective anorectic medications were when used as an adjunct to behavior modification and diet. This aspect was addressed in the first two years of the clinical trial under consideration here.