Appendectomy and risk of Parkinson's disease: A nationwide cohort study with more than 10 years of follow-up.

Abstract

The appendix may be a key site for the initiation of Parkinson's disease (PD) pathology. We examined the hypothesis that appendectomy is associated with lower PD risk. We used Danish medical and administrative registries to construct a cohort of all patients in Denmark with an operation code of appendectomy during 1980-2010 (n = 265,758) and a matched general population comparison cohort (n = 1,328,790). Using Cox regression, we computed hazard ratios and corresponding 95% confidence intervals for PD, adjusting for potential confounders and stratifying on age at appendectomy (≤45 years / > 45 years), sex, and follow-up time. During follow-up ( > 10 years), PD incidence was 0.19 and 0.15 per 1,000 person-years at risk in the appendectomy cohort and in the general population comparison cohort, respectively, yielding a slightly increased risk of PD (adjusted hazard ratio = 1.14; 95% confidence interval 1.03-1.27). Findings were consistent after more than 20 years of follow-up and when stratified on age of appendectomy and sex. Appendectomy was associated with a small increase in PD risk 10 or more years after surgery. © 2016 International Parkinson and Movement Disorder Society.