WEUSKOP5723: Prostate Cancer Study

A retrospective cohort study from 1992-2010 will be conducted using data from 4 Kaiser sites: Kaiser Permanente Southern California (KPSC), Kaiser Permanente Northern California (KPNC), Kaiser Permanente Northwest (KPNW), and Kaiser Permanente Colorado (KPCO). Men treated with BPH medications, 5ARIs (with and without concomitant and/or previous alpha-blocker use) will be compared to men treated with alpha-blockers. A matched design will be used with each man treated with 5ARIs being matched with 5 or 6 men treated with alpha-blockers. Men 50 years or older at the time of their first prescription for a study defined BPH medication, initiating treatment between 1992 and 2008 with at least 1-year of coverage in the healthcare system before the first prescription for BPH medication and at least 3 consecutive prescriptions (90 days of supply) for a BPH medication will be eligible for inclusion in the study. Men with a diagnosis of prostate cancer any time before the first prescription for BPH medication, having a diagnosis of prostate cancer within 3 months after initiation of their first BPH medication, and those treated with finasteride 1mg prior to their BPH medication will be excluded from the study. 5ARI initiators will be matched to alpha-blocker users in a ratio of 1:5 or 1:6 to yield an overall matching ratio of 1:5.4. Matching factors include age (+/- 1 year), timing of BPH treatment initiation (+/- 1 year), race, and duration of prior use of alpha-blockers. Based on the feasibility study from KPSC, there will be approximately 284,000 men treated with BPH medications meeting eligibility criteria for inclusion in the study sample. The data will be analyzed using Kaplan Meier curves comparing the 5ARI vs alpha-blocker users for the primary and secondary study outcomes, without any adjustments. Additionally, a plot of cumulative incidence, adjusting for competing risks of death, will be constructed allowing for the investigation of the effect of competing risks on the Kaplan-Meier probability estimates. Crude mortality rates and incidence rates of metastatic cancer will be calculated. Cox proportional hazard regression models will be fit to compare the primary and secondary outcomes between groups using hazard ratios, while adjusting for pre-treatment characteristics.