Osteoarthritis and Neurological Disorder Diagnoses in Adults: A Meta-Analysis Examining Associations With Parkinson's Disease, Multiple Sclerosis, and Alzheimer's Disease.

Osteoarthritis (OA) is a highly prevalent joint disorder that is emerging as a global threat to health. OA is associated with low-grade chronic systemic inflammation that can affect overall health, leading to a sedentary lifestyle and potentially increased risk of neurological disorders (ND) such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). A meta-analysis was conducted following the Preferred Reporting Items for 2020 Systematic Reviews and Meta-Analyses (PRISMA) guidelines. MEDLINE, Web of Science, and Embase databases were searched to identify records. The inclusion criteria for this analysis were original research articles reporting on OA and neurological disorder diagnoses (AD, PD, or MS) with non-OA comparator groups. Logarithmic odds ratios (LORs) were calculated and input into a random-effects meta-analysis using the restricted maximum-likelihood estimator. Subgroup analyses examined the associations between OA, AD, PD, and MS. A subsequent meta-regression analysis was performed to explore potential sources of heterogeneity, focusing on comorbidities and demographic factors. Publication bias was evaluated using funnel plots, Egger's test, and trim-and-fill analysis. Nine studies were included in this meta-analysis (six case-control designs, two cross-sectional designs, and one population-based cohort design) of 1,837,716 cases. The pooled odds ratio (OR) indicated a significant association between OA and ND diagnosis (OR = 1.246; confidence interval (CI): 1.01-1.53). Subsequent subgroup analyses were not statistically significant but indicated an association with PD (OR = 1.31, CI: 0.80-2.12), MS (OR = 1.12, CI: 0.80-2.81), and AD (OR = 1.50, CI: 0.80-2.81). This meta-analysis revealed that individuals with OA have approximately 25% higher odds of an accompanying ND diagnosis compared to those without OA. Importantly, these findings represent statistical associations only and do not imply causation or directionality but provide insight into factors, including shared risk factors, overlapping symptoms, or other underlying mechanisms that may influence the observed relationships.