Does mental health mediate the effect of nonsurgical exposures on pain and functional outcomes in osteoarthritis? A systematic review

Mental health issues are common in osteoarthritis (OA), however it is unclear whether change in mental health status affects future OA outcomes. The aim of this systematic review was to assess whether mental health mediates the effects of nonsurgical exposures on pain and functional outcomes in individuals with OA. Full peer-reviewed reports of studies that tested a mental health mediator between any non-surgical exposure and a range of pain or functional outcomes among people with OA were included. PubMed, EMBASE, Scopus, PsycInfo, Web of Science, ClinicalTrials.gov, and WHO ICTRP were searched from inception through April 2025. Risk of bias for the main study outcome was assessed using the Cochrane Risk of Bias 2 tool and Joanna Briggs Institute critical appraisal tools. The AGReMA reporting guideline was used to assess the reporting of each included study. Eleven studies totalling 8,069 participants and 32 unique models were included. Potential mediators included depression, anxiety, and general mental health. Depression was tested in 9 studies with 6 of these studies indicating that depression acts as a mediator. Anxiety and mental health were tested in two studies and mediated the relationships tested in those studies. Our findings provide preliminary evidence that mental health may mediate the effect of nonsurgical exposures on functional outcomes in people with OA. Key methodological weakness in the included studies diminishes the strength of this conclusion. The main limitation this review encountered was high heterogeneity across proposed models. PROSPERO ID CRD42023465046.