Functional somatic syndromes and joint hypermobility: A systematic review and meta-analysis

Objective: There have been multiple reports of increased joint hypermobility (JH) in functional somatic syndromes (FSS). We sought to evaluate the evidence for an association. Methods: A systematic search of the databases Medline and PsycINFO was conducted to identify all controlled studies from inception to February 2020 measuring the association of an FSS and JH. Records were identified and screened, and full-text articles assessed for eligibility by two independent authors. Meta-analysis was performed using random-effects modelling with the DerSimonian and Laird method. Results: We found 220 studies initially, which yielded 11 studies for inclusion in the qualitative review and 10 in the quantitative analysis - 5 studies on fibromyalgia, 3 on chronic fatigue syndrome and 3 on functional gastrointestinal disorder. Nine of the 11 studies found increased rates of JH in FSS compared to controls, though most studies were fair to poor in quality. Meta-analysis showed a weighted summary effect odds ratio of 3.27 (95% CI: 1.83, 5.84; p < 0.001) of JH in FSS, suggesting greater odds of FSS in individuals with JH than in those without. Conclusions: There is some evidence for an association between FSS and JH, but this is limited by the generally poor quality of studies and the narrow range of FSS studied. Better research is needed to confirm these findings as well as evaluate causation using prospective cohort studies.