Trial Information

Prostate Cancer in Benign Prostatic Hyperplasia (BPH) Patients

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.