Risk of Parkinson’s disease after human papillomavirus infection: a nationwide cohort study

Background: Little is known about the association between human papillomavirus (HPV) infection and Parkinson’s disease (PD). This study aimed to explore the risk of incident PD following HPV infection. Methods: Patients 40 years or older with HPV infection diagnosed between 1996 and 2013 were included in the case group and were 1:4 matched with controls from the Taiwan National Health Insurance Research Database. A second matched control group of patients with acute respiratory infection (ARI) was also included. The outcome was incident PD, as determined using Cox proportional hazards. Results: The study population included 80,318 patients with HPV infection, 322,952 non-HPV infection matched controls, and 80,318 ARI infection matched controls. There were 456 incident PD cases in the HPV group (0.84 per 1000 person-year), 2499 in the control group (0.43 per 1000 person-year), and 655 in the ARI control group (0.45 per 1000 person-year). After adjustment for confounding factors, patients with HPV infection were associated with a 1.25-fold higher risk of incident PD (hazard ratio, 1.25, 95% confidence interval, 1.13 to 1.39) than controls. This finding remains consistent when comparing to the ARI control group and in sensitivity analyses. Stratified by sex, only male patients with HPV infection had a 1.48-fold higher risk of PD compared with the control group (1.28 to 1.71) and a 1.31-fold higher risk of PD compared with the ARI control group (1.09 to 1.59); however, no significant associations were observed in the female patients with HPV. Conclusions: This study suggests an increased risk of incident PD in patients with HPV infection, especially for males.