| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
LETTER TO THE EDITOR |
Sticht Center on Aging
Wake Forest University School of Medicine
Winston-Salem, NC 27157
E-mail: skritche{at}wfubmc.edu
Dear Sir:
In 1980, the Coronary Drug Project (CDP) Research Group published data to warn against the practice of analyzing randomized trial treatment group data by adherence status for evidence of the efficacy of the treatment (1). Using data from the trial's placebo group (Table 1
), they found that participants taking <80% of the per-protocol placebo dose (nonadherers) had a 5-y total mortality rate nearly 90% higher than that of participants taking 
80% of the dose (adherers), a differential that could not be explained by the potential confounding variables (
20) examined. Whereas this story is of obvious relevance to the clinical trialist, it is also a cautionary tale for the nutritional epidemiologist. In any sample of persons enumerated as part of a cohort study, there will be a percentage of persons who would be nonadherers were they participants in a randomized trial. Their presence could lead to substantial confounding if nonadherer status is associated with the exposure of interest.
|
7 eggs/d to total mortality risk in physicians with diabetes who were enrolled in the Physicians' Health Study (2). The result is hard to understand on its own because of the lack of association between egg consumption and myocardial infarction and stroke risk in that study, which suggests that high egg consumption is associated with noncardiovascular causes of death, an association for which there is no apparent biologic basis. There is no test or questionnaire that can reliably predict who may be a nonadherer, but it is not a reach to think that, among physicians with diabetes, a group that should have the knowledge, motivation, and resources to minimize the adverse consequences of diabetes through both dietary and nondietary means, the consumption of high-cholesterol foods could be considered nonadherent behavior. The data showing that high consumers of eggs smoke more and are more sedentary than are those with lower egg consumption support the idea that the egg consumption may a marker of nonadherer status. One would further predict that this group would be less adherent to all American Diabetes Association and American Heart Association dietary guidelines, although the data needed to examine this issue were not collected. Because the study by Djoussé and Gaziano is an epidemiologic study nested in a randomized controlled trial of low-dose aspirin and β-carotene use, those investigators could address this issue head-on by relating egg-consumption patterns to adherence to the allocated intervention, and adherence to the allocated regimen could be controlled for in the analysis to deal, at least partially, with this potential source of bias. The question of why people select the foods they do should be an important area of research in nutritional epidemiology. Diets are selected for a variety of reasons, including tradition, socioeconomic status, cost, availability, and beliefs and attitudes regarding the role of food in maintaining health, as opposed to other roles that food plays in a person's life. The answer to this question is critical to an understanding of the true health benefit of a given diet, because the determinants of the reasons that foods are selected may be a predictor of future health outcomes, independent from the metabolic effects of the diet itself. The potential effect of these behavioral factors can be appreciated from the Coronary Drug Project experience.
ACKNOWLEDGMENTS
The author is a consultant for the Nestlé Corporation and is on the scientific advisory board of the Egg Nutrition Center.
REFERENCES
This article has been cited by other articles:
|
|
 |
|
  J. Curran Celentano Where Do Eggs Fit in a Heart-Healthy Diet? American Journal of Lifestyle Medicine, July 1, 2009; 3(4): 274 - 278. [Abstract] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
