Abstract
PURPOSE: Medical therapy is the first-line treatment for lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH). However, predictors of treatment failure in men with small prostate volume (<30 ml) remain poorly defined. This study aimed to develop and temporally validate a simple bedside risk score for predicting medical therapy failure in this specific subgroup. METHODS: We performed a retrospective cohort study of 201 men aged ≥50 years with IPSS ≥8 and prostate volume <30 ml who started medical therapy between 2015 and 2025. Treatment failure was defined as surgical intervention, acute urinary retention or IPSS worsening by ≥4 points. Independent predictors were identified using multivariable logistic regression. A practical integer risk score was derived from the strongest predictors. Temporal validation was conducted by splitting the cohort chronologically (derivation set 2015-2020, n = 120; validation set 2021-2025, n = 81). RESULTS: During a median follow-up of 24 months, 66 patients (32.8%) experienced treatment failure. Independent predictors included higher IPSS, greater BPH Impact Index, increased intravesical prostatic protrusion, lower maximum flow rate, higher post-void residual volume and diabetes mellitus. The bedside risk score stratified patients into low-risk (0-3 points: 11.0% failure), moderate-risk (4-7 points: 32.9%) and high-risk (8-13 points: 77.5%) categories. The model demonstrated good discrimination (AUC 0.789; bootstrap-corrected 0.782) and maintained strong performance in temporal validation (derivation AUC 0.799; validation AUC 0.821). CONCLUSION: This novel bedside risk score reliably predicts medical therapy failure in small-volume BPH using readily available clinical parameters. It may enable early risk stratification and timely intervention, particularly in populations with high diabetes prevalence.