Recorded benign prostatic hyperplasia and subsequent Parkinson disease diagnosis: a nationwide population-based matched cohort study with an exploratory alpha-1 blocker analysis

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Background Previous studies of Parkinson disease (PD) in men with benign prostatic hyperplasia (BPH) have primarily compared alpha-1 blocker subclasses. Whether recorded BPH is associated with subsequent PD diagnosis, including among men with no recorded alpha-1 blocker use, remains uncertain. Methods We conducted a retrospective matched cohort study using the Longitudinal Health Insurance Database 2010 (1996–2013). Men aged 40–99 years with a first qualifying recorded BPH diagnosis during 2000–2012, following a minimum 4-year period without recorded BPH, were matched 1:1 by age and index date to men with no recorded BPH throughout the available claims period. BPH and PD each required at least two diagnostic claims. Cox proportional hazards models and propensity-score-adjusted Cox models evaluated subsequent recorded PD. An exploratory analysis classified patients with BPH as having long-term recorded alpha-1 blocker use exceeding 6 months or no recorded use; exposure was analyzed as a fixed category. Results The primary analysis included 21,564 men with recorded BPH and 21,564 controls. PD was diagnosed in 500 men with recorded BPH (2.3%) and 183 controls (0.8%). The propensity-score-adjusted hazard ratio (HR) was 2.45 (95% confidence interval [CI], 2.07–2.91). In the exploratory analysis, PD occurred in 186 of 8,664 long-term users (2.1%) and 41 of 1,991 patients with no recorded use (2.1%). Relative to controls, the corresponding propensity-score-adjusted HRs were 1.93 (95% CI, 1.56–2.38) and 2.80 (95% CI, 1.99–3.92). Conclusion Recorded BPH was associated with a higher proportion and hazard of subsequent recorded PD diagnosis. However, prodromal urinary dysfunction, differential surveillance, control selection, and residual confounding may have contributed to the association. Recorded BPH should therefore be interpreted as a possible clinical or care-pathway marker rather than a causal risk factor. The medication-stratified findings were exploratory and do not establish benefit or harm from alpha-1 blockers.