Effect of terazosin on clinical benign prostatic hyperplasia in older adults

The objective of this meta-analysis of randomized controlled trials (RCTs) of terazosin versus placebo in men with benign prostatic hyperplasia (BPH) was to evaluate the effect of terazosin on lower urinary tract symptoms.

BPH is common in older men; more than 90% of men aged 70 and older suffer from BPH. (1,2) BPH has substantial negative effect on quality of life, with symptoms that interfere with activities of daily living. (3) The symptoms of BPH are primarily due to bladder outlet obstruction and are caused by dynamic prostatic smooth muscle tone and static prostatic obstruction. (4,5) The smooth muscle tone is dependent on the degree of the alpha-1 adrenergic receptors present in the bladder neck, prostrate capsule, and prostrate gland. The blockade of alpha-1 receptors with drugs such as terazosin reduces bladder outlet obstruction by reducing the smooth muscle tone. STUDY SELECTION AND DATA SOURCES: Selected studies were all RCTs of terazosin with two primary end points, namely, changes in the peak urinary flow rates and urinary symptom scores from baseline. Nine studies were selected using a Medline search, the details of which were not provided. The studies were conducted in North America and Europe between 1992 and 1996. Two of the studies included unpublished data that were obtained from Abbott Laboratories, which is the manufacturer of terazosin (Hytrin). The company also provided data on the other seven studies.

The meta-analysis did not provide details of the data abstraction process. Urinary symptom score was measured using two different tools: the Boyarsky Symptom Index (BSI) and American Urology Association Symptom Index (AUA-SI). The BSI was used in seven studies and AUA-SI in two studies. The authors calculated a common symptom score, based on the common items from both questionnaires, that had all but one item used in the AUA-SI. Questions from AUA-SI are scored on a 0 to 5 scale and those on BSI on a 0 to 3 scale. To adjust for this difference, the authors performed a nonlinear rescaling of the AUA-SI to adjust for these scoring differences.

The ages of the patients (N = 3,948) ranged from 62 to 66. The duration of the studies varied from 8 to 52 weeks. Four of the studies used fixed dosages, and the rest used titration-to-response doses. The effect of terazosin versus placebo on peak urinary flow rate was similar in all the studies. The estimated mean increase in peak urinary flow rate was 1.39 mL/s greater in men receiving terazosin than in those receiving placebo, and the improvements were observed within 8 weeks of therapy. However, the changes in the symptom scores varied across the studies. Patients treated with terazosin had an estimated 1.9-point reduction (95% confidence interval (CI) = 1.6-2.3) in BSI and 3.5-point reduction (95% confidence interval (CI) = 2.8-4.1) in AUA-SI score from baseline. Improvements in scores were greater in studies that were conducted for longer duration.

The authors concluded that treatment with terazosin was associated with greater peak urinary flow rate and lower symptom score than treatment with placebo. There was no variability of efficacy of terazosin as a result of prostrate volume, and measurement of prostrate volume was not essential before initiation of therapy.