Abstract
BACKGROUND: The global prevalence of lower urinary tract symptoms suggestive of benign prostate hyperplasia (LUTS/BPH) escalates, with obesity recognized as a major contributing factor. However, the association between the relative fat mass (RFM) and LUTS/BPH remains unexplored. This 7-year follow-up study aimed to investigate the cross-sectional and longitudinal relationships between RFM and LUTS/BPH. METHODS: Based on the China Health and Retirement Longitudinal Study (CHARLS) data, we interpolated missing values of covariates using multivariate imputation via chained equations grounded on the random forest method. Stratifying participants by tertiles of RFM, we employed multivariate binary logistic and restricted cubic spline (RCS) regressions to assess the odds ratio (OR) and dose-response relationship between RFM and LUTS/BPH. Subgroup and interactive analyses assessed covariate impacts. Sensitivity analysis involved stratifying RFM by median and quartiles and excluding males aged ≤60 years to confirm model robustness. A retrospective cohort [2011-2018] was used to investigate longitudinal associations, with additional cohorts [2011-2013, 2011-2015] for further sensitivity checks. RESULTS: A total of 6,253 males aged over 40 years were included in the 2011 baseline survey, with 4,321 observed in the 2018 follow-up. The final model revealed a positive correlation between high RFM and prevalent LUTS/BPH. Specifically, the risk for the third tertile group increased by a factor of 1.47 [95% confidence interval (CI): 1.16-1.87; P=0.001]. No significant interactive effects were observed. Linear trends were confirmed by RCS regression across demographics (P for overall <0.05). In the 2011-2018 cohort, the final model linked high RFM to a 1.41 times higher incidence of LUTS/BPH (95% CI: 1.11-1.80; P=0.003) in the third tertile subgroup. All sensitivity analyses consistently affirmed these positive associations. CONCLUSIONS: Positive cross-sectional and longitudinal associations between RFM and LUTS/BPH were observed, underscoring RFM's potential as a valuable predictor for prompt detection targeting LUTS/BPH in aging males. Consequently, early management and treatment strategies could be implemented.