IGF1 and benign prostatic hyperplasia: After controlling for all potential covariates including demographic variables, socioeconomic variables and lifestyle variables, only apolipoprotein A (HR = 0.76; 95% CI = 0.70–0.81, P < 0.001), HDL (HR = 0.83; 95% CI = 0.79–0.88, P < 0.001), gamma glutamyl transferase (HR = 0.99; 95% CI = 0.99–1.00, P < 0.001), and IGF-1 (HR = 1.00; 95% CI = 1.00–1.01, P < 0.001) remained highly correlated with incidence of BPH.