Temporal trends in the prevalence of Parkinson's disease from 1980 to 2023: a systematic review and meta-analysis

Background Parkinson's disease is the second most common neurodegenerative disorder, exhibiting an upward trend in prevalence. We aimed to investigate the prevalence of Parkinson's disease, temporal trends between 1980 and 2023, and variations in prevalence by location, age, sex, survey period, sociodemographic index (SDI), human development index (HDI), and study characteristics (sample size, diagnostic criteria, and data source). Methods In this systematic review and meta-analysis we searched PubMed, Cochrane, Web of Science, Embase, Scopus, and Global Health for observational studies that reported Parkinson's disease prevalence in the general population from database inception to Nov 1, 2023. We included studies if they were original observational investigations, had participants from the general population or community-based datasets, and provided numerical data on the prevalence of Parkinson's disease either with 95% CIs or with sufficient information to calculate 95% CIs. Studies were excluded if they were conducted in a specific population, had a sample size smaller than 1000, or were review articles, case reports, protocols, meeting abstracts, letters, comments, short communications, posters, and reports. The publication characteristics (first author and publication year), study location (countries, WHO regions, SDI, and HDI), survey period, study design, diagnostic criteria, data source, participant information, and prevalence data were extracted from articles using a standard form. Two authors independently evaluated eligibility, and discrepancies were resolved through discussion with the third author. We used random effect models to pool estimates with 95% CIs. Estimated annual percentage change (EAPC) was calculated to assess the temporal trend in prevalence of Parkinson's disease. The study was registered with PROSPERO, CRD42022364417. Findings 83 studies from 37 countries were eligible for analysis, with 56 studies providing all-age prevalence, 53 studies reporting age-specific prevalence, and 26 studies providing both all-age and age-specific prevalence. Global pooled prevalence of Parkinson's disease was 1<middle dot>51 cases per 1000 (95% CI 1<middle dot>19-1<middle dot>88), which was higher in males (1<middle dot>54 cases per 1000 [1<middle dot>17-1<middle dot>96]) than in females (1<middle dot>49 cases per 1000 [1<middle dot>12-1<middle dot>92], p=0<middle dot>030). During different survey periods, the prevalence of Parkinson's disease was 0<middle dot>90 cases per 1000 (0<middle dot>48-1<middle dot>44; 1980-89), 1<middle dot>38 cases per 1000 (1<middle dot>17-1<middle dot>61; 1990-99), 1<middle dot>18 cases per 1000 (0<middle dot>77-1<middle dot>67; 2000-09), and 3<middle dot>81 cases per 1000 (2<middle dot>67-5<middle dot>14; 2010-23). The EAPC of Parkinson's disease prevalence was significantly higher in the period of 2004-23 (EAPC 16<middle dot>32% [95% 6<middle dot>07-26<middle dot>58], p=0<middle dot>0040) than in the period of 1980-2003 (5<middle dot>30% [0<middle dot>82-9<middle dot>79], p=0<middle dot>022). Statistically significant disparities in prevalence were observed across six WHO regions. Prevalence increased with HDI or SDI. Considerable variations were observed in the pooled prevalence of Parkinson's disease based on different sample sizes or diagnostic criteria. Prevalence also increased with age, reaching 9<middle dot>34 cases per 1000 (7<middle dot>26-11<middle dot>67) among individuals older than 60 years. Interpretation The global prevalence of Parkinson's disease has been increasing since the 1980s, with a more pronounced rise in the past two decades. The prevalence of Parkinson's disease is higher in countries with higher HDI or SDI. It is necessary to conduct more high-quality epidemiological studies on Parkinson's disease, especially in low SDI countries.