The causal effect of metabolic syndrome and its components on benign prostatic hyperplasia: A univariable and multivariable Mendelian randomization study

Previous observational studies have indicated that metabolic abnormalities are associated with benign prostatic hyperplasia (BPH). The limitations of the research methodology of observational studies do not allow causal inference to be drawn; however, Mendelian randomization (MR) can clarify this.Using summary-level data from genome-wide association studies, we conducted a two-sample MR study to examine the causality of the metabolic syndrome (MetS) and its components on BPH (26,358 BPH cases and 110,070 controls). The random-effects inverse-variance weighted was employed as the primary method for MR analyses.We observed that genetically predicted waist circumference (WC) (odds ratio [OR] = 1.236, 95% confidence interval [CI]: 1.034-1.478, p = 0.020) and diastolic blood pressure (DBP) (OR = 1.011, 95% CI: 1.002-1.020, p = 0.020) were significantly positively associated with BPH risk. We did not identify a causal effect of MetS (OR = 0.975, 95% CI: 0.922-1.031, p = 0.375), systolic blood pressure (OR = 1.004, 95% CI: 0.999-1.008, p = 0.115), triglycerides (OR = 1.016, 95% CI: 0.932-1.109, p = 0.712), high-density lipoprotein (OR = 1.005, 95% CI: 0.930-1.086, p = 0.907), and fasting blood glucose (OR = 1.037, 95% CI: 0.874-1.322, p = 0.678) on BPH. In the multivariable MR analysis, we observed that the risk effect of DBP (OR = 1.013, 95% CI: 1.000-1.026, p = 0.047) on BPH persisted after conditioning with WC (OR = 1.132, 95% CI: 0.946-1.356, p = 0.177).Our study provides genetic evidence supporting the causal effect of DBP on BPH, although the effect of WC needs to be further validated.