Increased risk of Parkinson's disease among patients with age-related macular degeneration

Background This study aimed to investigate the risk of Parkinson's disease (PD) among patients with age-related macular degeneration (AMD) and its association with confounding comorbidities. Methods A population-based retrospective cohort study was conducted using Longitudinal Health Insurance Database 2000 (LHID2000). We established AMD and non-AMD cohorts from January 1, 2000 to December 31, 2012 to determine the diagnosis of PD. A total of 20,848 patients were enrolled, with 10,424 AMD patients and 10,424 controls matched for age, sex, and index year at a 1:1 ratio. The follow-up period was from the index date of AMD diagnosis to the diagnosis of PD, death, withdrawal from the insurance program, or end of 2013. Multivariable Cox regression analysis was performed to examine the hazard ratio (HR) and 95% confidence interval (CI) for the risk of PD between the AMD and non-AMD cohorts. Result After adjusting for potential confounders, there was a higher risk of developing PD in the AMD cohort than in the non-AMD cohort (adjusted HR = 1.35, 95% CI = 1.16-1.58). A significant association could be observed in both female (aHR = 1.42, 95% CI = 1.13-1.80) and male (aHR = 1.28, 95% CI = 1.05-1.57) patients, aged more than 60 years (60-69: aHR = 1.51, 95% CI = 1.09-2.09, 70-79: aHR = 1.30, 95% CI = 1.05-1.60; 80-100: aHR = 1.40, 95% CI = 1.01-1.95), and with more than one comorbidity (aHR = 1.40, 95% CI = 1.20-1.64). A significant association between increased risk of PD and AMD was observed among patients with comorbidities of osteoporosis (aHR = 1.68, 95% CI = 1.22-2.33), diabetes (aHR = 1.41, 95% CI = 1.12-1.78) and hypertension (aHR = 1.36, 95% CI = 1.15-1.62) and medications of statin (aHR = 1.42, 95% CI = 1.19-1.69) and calcium channel blocker (CCB) (aHR = 1.32, 95% CI = 1.11-1.58). The cumulative incidence of PD was significantly higher over the 12-year follow-up period in AMD cohort (log-rank test, p < 0.001). Conclusions Patients with AMD may exhibit a higher risk of PD than those without AMD.