Leptin, adiposity, and mortality: results from the National Health and Nutrition Examination Survey III, 1988 to 1994

Abstract

Objective: To determine whether leptin is related to all-cause and cardiovascular (CV) mortality in older adults.

Patients and methods: Participants 60 years and older with plasma leptin level measurements from the National Health and Nutrition Examination Survey III (1988-1994) and mortality data linked to the National Death Index were included. We created sex-specific tertiles of leptin (men: 4.2-7.7 μg/L; women: 11.5-21.4 μg/L) to identify the effect of leptin on all-cause and CV mortality. We also determined whether leptin predicted mortality in patients with obesity. We classified obesity using 4 possible definitions: body mass index 30 kg/m(2) or greater; body fat 25% or more in men and 35% or more in women; waist circumference 102 cm or greater in men and 88 cm or greater in women; and waist-hip ratio 0.85 or higher in women and 0.95 or higher in men. Sex-specific proportional hazard models were used to assess the effect of leptin on all-cause and CV mortality.

Results: Of 1794 participants, 51.6% were women; the mean age was 70.3±0.4 years, and the follow-up period was 12.5 years with 994 deaths (469 were CV deaths). All-cause mortality in the highest leptin tertile was significant neither in men (hazard ratio [HR], 1.23; 95% CI, 0.93-1.63) nor in women (HR, 0.97; 95% CI, 0.68-1.40). CV mortality was the highest in the highest leptin tertile in men (HR, 1.69; 95% CI, 1.06-2.70) but not in women (HR, 1.21; 95% CI, 0.73-1.98). Evaluating the effect of leptin in subgroups of different obesity definitions, we found that high leptin levels as predict CV mortality in men as measured by waist circumference or body fat.

Conclusion: Elevated leptin level is predictive of CV mortality only in men. Leptin may provide additional mortality discrimination in obese men.