Caldwell Esselstyn's Study and Its Follow-Up

Harriet Hall here writes "

Caldwell Esselstyn

Esselstyn did an uncontrolled interventional study of patients with angiographically documented severe coronary artery disease who were not hypertensive, diabetics, or smokers. He wanted to test how effective one physician could be in helping patients achieve a total cholesterol level of 150 mg/dL or less, and what effect maintaining that level would have on coronary disease. Patients agreed to follow a plant-based diet with <10% of calories derived from fat. They were asked to eliminate oil, dairy products (except skim milk and no-fat yogurt), fish, fowl, and meat. They were encouraged to eat grains, legumes, lentils, vegetables, and fruit. Cholesterol-lowering medication was individualized.

There were originally 24 patients: 6 dropped out early on, 18 maintained the diet, one of these 18 died of an arrhythmia and 11 completed a mean of 5.5 years followup. Repeat angiography showed that of 25 coronary artery lesions, 11 regressed and 14 remained stable. At 10 years, 11 patients remained: 6 continued the diet and had no further coronary events; 5 resumed their pre-study diet and reported 10 coronary events.

In a 12 year followup report, the 6 who had maintained the diet at 10 years and the 5 who had gone off it and had coronary events had apparently somehow morphed into 17 patients who had remained adherent to the diet and who had had no coronary events. I couldn’t understand the discrepancy in numbers; perhaps readers can explain it to me if I missed something."

First off, it may seem that another number doesn't match in that the follow-up study says that the original study had 24 patients, while the first study above mentions 22.  But, the first study says "The study included 22 patients with angiographically documented, severe coronary artery disease that was not immediately life threatening."  So, there isn't any necessarily contradiction in numbers there.

Second, the first study says "Of the 22 participants, 5 dropped out within 2 years, and 17 maintained the diet, 11 of whom completed a mean of 5.5 years of follow-up."  This does NOT say that 11 of them, implying that 6 quit the diet, but that 11 of them engaged in follow-up.  As the follow-up study says: "At 5 years, 11 of these patients underwent angiographic analysis by the percent stenosis method, which demonstrated disease arrest in all 11 (100%) and regression in 8 (73%)."  So, the 11 who completed the follow-up appears to refer to the patients who completed angiograms.  6 of the 17 didn't complete follow-up by not engaging in angiograms.

Another discrepancy in the numbers may appear to exist in that the follow study says "The remaining 18 patients adhered to the study diet and medication for 5 years.", while the first indicates 17 maintaining the diet.  But, that 17 number appears in the passage about 5.5 years of follow-up and the second study says "One patient admitted to the study with <20% left ventricular output died from a ventricular arrhythmia just weeks after the 5-year follow-up angiogram had confirmed disease regression.  Autopsy revealed no myocardial infarction. "  So, there doesn't exist any contradiction there.
A further discrepancy may seem to exist in that the first study says "Among the 11 remaining patients after 10 years, six continued the diet and had no further coronary events, whereas the five dropouts who resumed their prestudy diet reported 10 coronary events."  This might seem like 5 more patients (5 out of the 22 who had angiographically documented coronary artery disease) dropped out of the study, which would contradict 17 patients in the follow study.  However, the five dropouts here probably refers to the original 5 of the original 22 angiographically documented patients who dropped out of the dietary program withing 2 years.  Esselstyn may have only mentioned 6 continuing the diet here, because he was only able to verify 6 still on the dietary plan when he published this.  The other 11 (not all angiographically documented patients) he may not have verified as still on the dietary plan until later... and that's perhaps part of the reason why he provided the update to the study in the first place.