The association of insulin-like-growth factor 1 (IGF-1) with incident coronary heart disease in women: Findings from the prospective British Womenʹs Heart and Health Study

Objective To examine the association of insulin-like-growth factor 1 (IGF-1) with coronary heart disease (CHD) in women. Methods Prospective (4 year) case–control study nested within the British Womenʹs Heart and Health Study. With 167 cases and 333 controls. Serum IGF-1 concentrations (on serum stored at −80 °C for a median of 4 years) were determined using a two-site immunoenzymometric assay. Results Among both cases and controls IGF-1 was inversely correlated with waist:hip ratio, fasting insulin, HOMA-IR, CRP, triglyceride levels and systolic blood pressure, and was positively correlated with HDL-C levels. The confounder-adjusted (age, socioeconomic position, smoking and physical activity) relative risk ratio for a 1 standard deviation (S.D.) increase in IGF-1 was 0.92 (95% CI: 0.75, 1.12) and additional adjustment for metabolic risk factors (waist:hip ratio, systolic blood pressure, high-density lipoprotein cholesterol, triglycerides, glucose, insulin and C-reactive protein) attenuated this to 0.98 (95% CI: 0.80, 1.21). There was no evidence of non-linear associations and the risk of CHD was similar across quarters of the distribution of IGF-1. Conclusions Despite associations with established CHD risk factors in this, and other studies, our findings suggest that higher IGF-1 levels are not associated with CHD in older British women. The contradictory evidence to date in this area highlights the need for further large-scale prospective studies and use of genetic epidemiology studies to determine the nature of the association between IGF-1 and CHD.