Appendectomy Does Not Increase the Risk of Future Emergence of Parkinson’s Disease: A Meta-analysis

Abstract

Objective To explore the impact of appendectomy history on emergence of Parkinson’s disease (PD). Background Although there are several studies to investigate the relationship between appendectomy history and emergence of PD, the results are still controversial. Methods We performed a comprehensive electronic search of the literature (the Cochrane Library, PubMed, and the Web of Science) up to April 2020 to identify studies that had employed databases allowing comparison of emergence of PD between patients with and those without appendectomy history. To integrate the impact of appendectomy history on emergence of PD, a meta-analysis was performed using random-effects models to calculate the risk ratio (RR) and 95% confidence interval (CI) for the selected studies, and heterogeneity was analyzed using I2 statistics. Results Four studies involving a total of 6 080 710 patients were included in this meta-analysis. Among 1 470 613 patients with appendectomy history, 1845 (.13%) had emergences of PD during the observation period, whereas among 4 610 097 patients without appendectomy history, 6743 (.15%) had emergences of PD during the observation period. These results revealed that patients with appendectomy history and without appendectomy had almost the same emergence of PD (RR, 1.02; 95% CI, .87-1.20; P = .83; I2 = 87%). Conclusion This meta-analysis has demonstrated that there was no significant difference in emergence of PD between patients with and those without appendectomy history.

Long-term Risk of Parkinson Disease Following Influenza and Other Infections

“…17,34 Two studies have shown that appendectomy is associated with an increased risk of subsequent PD, perhaps owing to the preceding inflammatory state of appendicitis, 35,36 but others have not found an association. 37 Research results are sparse and mixed as to whether specific infections increase risk of PD, with Helicobacter pylori and hepatitis C virus infections emerging as particularly relevant. [38][39][40] Case counts were too low for H pylori in our data to examine this association independently, and the confidence intervals were too wide to interpret any association between viral hepatitis and PD.…”

“…Other studies have examined whether infections are associated with PD, with one hypothesized mechanism of action being central nervous system inflammation as a consequence of systemic infection . Two studies have shown that appendectomy is associated with an increased risk of subsequent PD, perhaps owing to the preceding inflammatory state of appendicitis, but others have not found an association . Research results are sparse and mixed as to whether specific infections increase risk of PD, with Helicobacter pylori and hepatitis C virus infections emerging as particularly relevant .…”

Risk of Parkinson's disease after anaesthesia and surgery

“…To date, empirical studies have been inconsistent, and two large meta-analyses failed to find a beneficial effect on lowering PD rates after appendicectomy. 8,9 There are a few known factors such as age, sex, race, and diseases of the colon that are possibly associated with appendicitis. We matched closely on such factors thereby removing potential bias if these same factors were associated with PD.…”

Parkinson’s Disease and the Gut: Symptoms, Nutrition, and Microbiota

“…Two independent histological studies have reported an abundance of alpha-synuclein within the vermiform appendix and have suggested that an appendicectomy, may both lower the risk of developing PD and delay the age of onset [34]. A large, nested control study conducted by Liu et al also concluded that an appendectomy was associated with a lower risk of PD [35], but interestingly, a 2021 meta-analysis demonstrated no significant difference in emergence of PD between patients with and those without an appendectomy history [36]. Moreover, LP findings have also been replicated in animal models, with aggregations of alpha-synuclein found in the GIT of both early and advanced PD [37, 38].…”