This research involved 3,040 men with symptoms of benign prostatic hyperplasia (BPH), or enlarged prostate, who enrolled in a four-year, double-blind, placebo-controlled protocol. The investigators were studying the use of a drug, finasteride, in BPH to lower the incidence of either acute urinary retention or a surgical procedure over the four-year period. According to the researchers, patients with moderate to severe symptoms and PSA test levels above 1.3 ng/ml were at increased risk of either acute retention or surgery. They noted that finasteride markedly reduced the risk of these outcomes by approximately 50% in all subgroups over the four-year period.