Objectives: To develop a prediction model, or nomogram, that would predict the probability that a man with benign prostatic hyperplasia would experience acute urinary retention (AUR) or require surgical intervention (SI) within 2 years, with or without dutasteride therapy.
Methods: We modeled 4294 men treated in the Phase III dutasteride benign prostatic hyperplasia trials. These men were characterized at baseline by a number of parameters, including the American Urological Association Symptom Index, Benign Prostatic Hyperplasia Impact Index questionnaire, prior use of selective alpha1-blockers, prostate volume, prostate-specific antigen level, and maximal flow rate. Cox proportional hazards regression analysis was used to relate these baseline variables to their future probability of AUR/SI within 2 years. The nomogram was internally validated with bootstrapping to assess its discrimination and calibration. Discrimination was quantified as the concordance index.
Results: The nomogram appeared to be accurately calibrated and discriminating (concordance index 0.71, P <0.001).
Conclusions: We constructed a nomogram for predicting the probability that a man would experience AUR or require SI within 2 years of benign prostatic hyperplasia diagnosis. At 24 months of follow-up, 7.4% of placebo patients and 3.7% of dutasteride patients had experienced AUR and/or SI, representing a 50% relative risk reduction and a 3.7% absolute risk reduction. For the greatest risk patient randomized to the Phase III dutasteride trial, the nomogram predicted a maximal risk of 27%, significantly greater than the median risk of the placebo-treated patients.