To investigate the possible association between osteoarthritis (OA) and the risk of dementia.
Cohort, case-control, and cross-sectional studies were obtained from wide literature search up to 20 April 2018 from following electronic databases: PubMed, Embase, Cochrane, using the MeSH terms: "osteoarthritis" AND "dementia". The literature search was then expanded to congress abstracts. After screening and selection of relevant studies by two investigators, data was extracted. Estimates were then calculated using a random-effect size model. Sensitivity-analysis was conducted for gender and age adjusted studies and pooled for studies with STROBE quality assessment score ≥75%. Publication bias was assessed by Funnel plot. Analyses were performed using Data Analysis and Statistical Software Version 14.2.
Nearly 1549 publication references were initially retrieved. Twenty-six publications were checked with full-text. Six observational studies with 388,252 individuals were included. OA was associated with a significantly increased risk for dementia (OR = 1.20; 95% confidence interval (CI), 1.03-1.39, I = 95.6%, P < .05). After pooling the studies with adjustment of age and gender, the risk increased (OR 1.36; 95% CI, 1.22-1.51, I = 75.6%, P < .0001). After pooling the study with a STROBE Quality score ≥75% the risk for dementia was slightly increased (OR 1.33; 95% CI, 1.17-1.5, I = 93.5%, p < 0.0001).
There is an association between osteoarthritis and the risk of dementia. This meta-analysis does not provide causality. Further prospective cohort studies are needed to clarify, if knee-, hip-, or hand-OA are independent risk factors for Alzheimer's disease and vascular dementia.