One of the serious limitations of the Lifestyle Heart Trial is the small number of people who were studied. There were 28 in the intervention group and 20 controls given conventional treatment who started the study. Only 60% of the control group were given cholesterol-lowering drugs and none of the intervention subjects was treated this way. The 28 intervention subjects were part of the group from the original study eight years ago, so there was self- selection for a willingness to follow the intervention plan, yet only 20 completed the 5-year follow up. Similarly, only 15 of the 20 controls completed this study.
Another limitation that was widely cited after the first paper was the inability of the coronary angiography method to discriminate the small changes reported. Coronary arteries are moving and twisting with every beat of the heart. It's fairly easy to see if 50% or 90% occlusion is present but it is extremely difficult to get a reproducible picture that can accurately measure the tiny changes reported. For instance, the differences in coronary stenosis were: a decrease of 2.3% in the intervention group but an increase of 11.8% in the control group. While the difference is statistically significant, the "noise" in the measurements with this method can be as much as 5-10%. Remember, that if the average change in the intervention group was a decrease of 2%, then half did not do as well and some must have shown an increase. Also, a coronary artery starts with a diameter of a pencil but quickly gets much narrower. This narrowing contributes to the difficulty in assessing small differences accurately.
The recent report stated there were 45 coronary events (defined as heart attack, bypass surgery, angioplasty, hospitalizations or death) in the 20 controls but only 25 events in the 28 intervention subjects. While this is an impressive difference, these numbers include the people who did not complete the regimen. Why were the subjects who dropped out included in this analysis? (This is precisely the kind of question Your Advisor would like you to ask yourself when reading about nutrition studies.) The numbers also show that most of the special intervention group still had coronary events, even though their arterial disease did not get worse. The intervention group had less frequent chest pain while the controls experienced more angina.
The changes in angina are critical to understanding what this program is doing to arteries. Dr. Ornish reported in 1983 that positive results were evident in 24 days. It is clear that changes in coronary artery plaques do not occur so quickly. There is no likely biological connection between the diet and how quickly symptoms decrease. One must question how much the psychological benefits are having. That is, are the stress reduction techniques and exercise more important? Would these alone show full benefit without the diet? It is impossible to answer these questions from this study. "Stabilization of coronary artery disease" just doesn't sell like a claim for reversal.
HERE'S WHAT YOU NEED TO KNOW: The Ornish program is very difficult for the average person to follow, but it seems to prevent further occlusion of arteries and leads to a decrease in symptoms.
Scientists are always looking for the single cause, but everyone agrees heart disease has many contributing factors. Therefore, the scientific establishment will probably never accept a multiple intervention trial like this one. Even if they did, convincing numbers would require several hundred patients in each group. This study is an intriguing preliminary report, which is the same thing some scientists said about the 1990 paper on this same group of patients.
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