Tonsillectomy and risk of Parkinson's disease: A danish nationwide population-based cohort study.

Background: We hypothesized that tonsillectomy modifies the risk of PD. Objectives: To test the hypothesis in a nationwide population-based cohort study. Methods: We used Danish medical registries to construct a cohort of all patients in Denmark with an operation code of tonsillectomy 1980-2010 (n=195,169) and a matched age and sex general population comparison cohort (n=975,845). Patients were followed until PD diagnosis, death, censoring, or end of follow-up 30 November 2013. Using Cox regression, we computed hazard ratios for PD and corresponding 95% confidence intervals, adjusting for age and sex by study design, and potential confounders. Results: We identified 100 and 568 patients diagnosed with PD among the tonsillectomy and general population comparison cohort, respectively, finding similar risks of PD (adjusted hazard ratio=0.95 [95% confidence interval: 0.76-1.19]; for>20 years' follow-up (adjusted hazard ratio=0.96 [95% confidence interval: 0.64-1.41]). Conclusion: Tonsillectomy is not associated with risk of PD, especially early-onset PD. (c) 2017 International Parkinson and Movement Disorder Society