COVID-19 and Parkinson's disease: a systematic review and meta-analysis.

This meta-analysis aimed to determine the prevalence, symptoms, and outcomes of COVID-19 in the elderly with Parkinson's disease (PD) by searching in the international databases of PubMed, Scopus, Web of Sciences, and EMBASE using the keywords of "COVID-19" and "Parkinson's." All articles related to Parkinson's disease and COVID-19 from January 2019 to October 20, 2021 were reviewed. The STATA software was used for analysis. A total of 20 articles were selected for data extraction in this meta-analysis, of which ten were cross-sectional studies (to determine the prevalence), five case-control studies, and five cohort studies (to examine the association). The results of the meta-analysis showed the prevalence of COVID-19 in patients with PD was 1.06% (95% CI 1.03-1.1%; P = 0.02), and the prevalence of their hospitalization due to COVID-19 was 0.98% (95% CI: 0.95-1.02%; P = 0.00). Also, the prevalence of depression and anxiety during the pandemic in this group was 46% (95% CI 29-64%; P = 0.00) and 43% (95% CI: 24-63%; P = 0.00), respectively. The prevalence of tremor and sleep problems were higher than those of other symptoms in the studied population. According to the results, there was no significant difference in the risk of COVID-19 infection between Parkinson's patients and healthy people. In other words, the risk of COVID-19 infection was equal in both groups (RR = 1.00 (CI 95% 0.77-1.30%; P = 0.15)). The results showed mortality and hospitalization rates of the elderly with Parkinson's disease were not significantly different from those of the general population during the COVID-19 pandemic. Also, the symptoms of Parkinson's disease and mental disorders increased during the COVID-19 pandemic. So, designing and developing more specific studies, like cohort studies, with large sample size is required for assessing these associations.