LEPTINEMIA IS NOT A RISK FACTOR FOR ISCHEMIC-HEART-DISEASE IN MEN - PROSPECTIVE RESULTS FROM THE QUEBEC CARDIOVASCULAR STUDY

OBJECTIVE - To investigate the possibility that leptin levels may be p redictive of the risk of ischemic heart disease (IHD) through the rela tionship of leptin to body fat. RESEARCH DESIGN AND METHODS - The Queb ec Cardiovascular Study cohort consisted of 2,103 French-Canadian men without IHD in 1985 who were followed until 1990, by which time 114 ha d experienced an IHD event. These 114 men were then individually match ed for age, BMI, cigarette smoking, and alcohol intake with 114 subjec ts who were free of IHD at follow-up. After exclusion of diabetic pati ents and those in whom leptin levels could not be measured, we were ab le to compare the initial metabolic profiles of 86 men in the IHD grou p and of 95 control subjects. RESULTS - Plasma leptin concentrations w ere positively correlated with BMI (r = 0.67, P < 0.0001) and with fas ting insulin concentrations (r = 0.46, P < 0.0001) in the overall samp le. These significant associations were also observed when men with IH D and the control subjects were examined separately (control subjects: r = 0.68 for BMI and r = 0.45 for insulin; IHD subjects: r = 0.65 for BMI and r = 0.50 for insulin). With the exception of plasma triglycer ide (r = 0.25, P < 0.001), no significant association was found betwee n leptin and plasma lipoprotein and lipid concentrations. Furthermore, plasma insulin remained significantly associated with leptin levels e ven after adjustment for BMI (r = 0.22, P < 0.005). There was no diffe rence in baseline leptin levels among men who developed IHD versus men who remained IHD-free during the 5-year follow-up (5.56 +/- 3.12 vs. 5.36 +/- 2.90 ng/ml, respectively). Thus, although significantly corre lated with the BMI and fasting insulin levels, plasma leptin concentra tion was not a significant predictor of the 5-year incidence of IHD. T his lack of a relationship to IHD was noted when leptin levels were an alyzed as tertiles and when leptin concentration was analyzed as a con tinuous variable. CONCLUSIONS - These prospective results suggest that leptinemia, despite being a strong correlate of obesity, does not app ear to be an independent risk factor for the development of IHD in men .