Appendectomy and risk of Parkinson's disease in two large prospective cohorts of men and women

BACKGROUND: Prior work on appendectomy and PD has produced mixed results. In this study we examined whether history of self-reported appendectomy was related to risk of incident Parkinson's disease in the Nurses' Health Study and the Health Professionals Follow-up Study. METHODS: We used the Cox proportional hazards model to estimate the hazard ratio of Parkinson's disease associated with self-report of appendectomy in men and women. Among women, we estimated the hazard ratio of Parkinson's disease associated with appendectomy for appendicitis and incidental appendectomy. RESULTS: In pooled analyses, self-report of any appendectomy was not related to Parkinson's disease risk: the hazard ratio of Parkinson's disease comparing participants who reported any appendectomy with those who did not was 1.08 (95% confidence interval, 0.94-1.23). In women, appendectomy for appendicitis, but not incidental appendectomy, was associated with a modestly elevated risk of Parkinson's disease (hazard ratio, 1.23 [95% confidence interval, 1.00-1.50]). CONCLUSIONS: Overall, this study suggests limited to no association between appendectomy and Parkinson's disease risk.