Does Prostate Size Predict the Development of Incident Lower Urinary Tract Symptoms in Men with Mild to No Current Symptoms? Results from the REDUCE Trial

Background It has been shown that increased prostate size is a risk factor for lower urinary tract symptom (LUTS) progression in men who currently have LUTS presumed due to benign prostatic hyperplasia (BPH). Objective To determine if prostate size is a risk factor for incident LUTS in men with mild to no symptoms. Design, setting, and participants We conducted a post hoc analysis of the REDUCE study, which contained a substantial number of men (n = 3090) with mild to no LUTS (International Prostate Symptom Score [IPSS] <8). Outcome measurements and statistical analysis Our primary outcome was determination of the effect of prostate size on incident LUTS presumed due to BPH defined as two consecutive IPSS values >14, or receiving any medical (α-blockers) or surgical treatment for BPH throughout the study course. To determine the risk of developing incident LUTS, we used univariable and multivariable Cox models, as well as Kaplan-Meier curves and the log-rank test. Results and limitations Among men treated with placebo during the REDUCE study, those with a prostate size of 40.1-80 ml had a 67% higher risk (hazard risk 1.67, 95% confidence interval 1.23-2.26, p = 0.001) of developing incident LUTS compared to men with a prostate size 40.0 ml or smaller. There was no association between prostate size and risk of incident LUTS in men treated with 0.5 mg of dutasteride. The post hoc nature of our study design is a potential limitation. Conclusions Men with mild to no LUTS but increased prostate size are at higher risk of incident LUTS presumed due to BPH. This association was negated by dutasteride treatment. Patient summary Benign prostatic hyperplasia (BPH) is a very common problem among older men, which often manifests as lower urinary tract symptoms (LUTS), and can lead to potentially serious side effects. In our study we determined that men with mild to no current LUTS but increased prostate size are much more likely to develop LUTS presumed due to BPH in the future. This association was not seen in men treated with dutasteride, a drug approved for treatment of BPH. Our study reveals that men with a prostate size of 40.1-80 ml are potential candidates for closer follow-up.