Sex Differences in the Association Between Insulin Resistance and Incident Coronary Heart Disease and Stroke Among Blacks Without Diabetes Mellitus: The Jackson Heart Study

BACKGROUND Studies exploring the association between insulin resistance (IR) and cardiovascular disease in blacks have not been conclusive, especially for coronary heart disease (CHD). The McAuley index and homeostasis model assessment of IR (HOMA-IR) perform differently in predicting cardiovascular disease. We investigated this association in the Jackson Heart Study, a large longitudinal cohort of blacks. METHODS AND RESULTS IR was estimated for 3565 participants without diabetes mellitus and cardiovascular disease at baseline using the McAuley index and HOMA-IR, and their associations with incident CHD and stroke (composite outcome) were compared. A lower McAuley index and higher HOMA-IR are indicative of IR. Cox regression analysis was used to estimate adjusted hazard ratios for incident CHD and/or stroke. There were 158 events (89 CHD-only, 58 stroke-only, and 11 CHD/stroke) over a median follow-up of 8.4 years. After adjustment for demographic factors, the risk of the composite outcome decreased with each SD increase in the McAuley index (hazard ratio 0.80; 95% CI: 0.67-0.96), with no attenuation after further accounting for CHD and stroke risk factors. When considered individually, McAuley index and HOMA-IR were associated with CHD (hazard ratio 0.71, 95% CI: 0.55-0.92 and hazard ratio 1.33, 95% CI: 1.03-1.72, respectively), but not stroke risk. The logHOMA-IR and CHD association was present in men, but not in women (Pinteraction=0.01). CONCLUSIONS Both HOMA-IR and the McAuley index demonstrate strong associations with CHD but not stroke risk in blacks. The logHOMA-IR and CHD association was present in men, but not in women.