Characterization of the response of symptomatic benign prostatic hyperplasia (BPH) to terazosin by prostate size

Objective: To assess whether a differential treatment response occurs with the alpha blocker terazosin in the treatment of men with symptomatic benign prostatic hyperplasia (BPH) when stratifying patients by baseline prostate volume. Materials and Methods: Data were combined from three randomized, placebo-controlled, double-blind trials which were three (n=198), six (n=313) and 12 (n=606) months in duration, and used similar enrollment criteria, with a terazosin dose ranging from 2 to 20 mg daily. Results: 1117 men were enrolled with a mean age of 64 ±7.1 (mean ± SE) years, a prostate volume determined by transrectal ultrasonography of 34.0±0.5 ml, a baseline symptom score of 17.3±6.4 AUA units, and a peak flow rate of 9.8±2.7 ml/sec. Two cohorts were formed stratified by baseline prostate volume: 71.3% had a volume of <40 ml with a mean of 25.5±0.2 ml, and 28.7% had volumes of ≥40 ml with a mean of 55.111.1 ml. The two cohorts were virtually identical at baseline regarding age, weight, symptom score and flow rate. Terazosin (n=636) and placebo (n=481) patients were well randomized. The following changes in outcome measures (difference between baseline and final visit) were noted: Terazosin Placebo Symptom Score (AUA Units) < 40ml -6.8±0.3 (-39%)* -3.9±0.4 (-23%) ≥ 40 ml -6.6±0.5 (-38%)* -3.4±0.6 (-18%) Peak Flow Rate (ml/sec) <40ml +2.7±0.2 (+28%)* +1.410.2 (+14%) ≥ 40 ml +2.8±0.4 (+31 %)* +0.9±0.4 (+9%) Conclusions: The terazosin responses are statistically significantly (*p<0.001) different from placebo. While the magnitude of symptom score and flow rate improvement under terazosin is independent of baseline prostate volume, the placebo effect appears to be diminished in men with larger prostates.