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

Highlights

• Joint hypermobility is associated with fibromyalgia and chronic fatigue syndrome.

• Joint hypermobility is associated with functional gastrointestinal disorder.

• Joint hypermobility could be a sign of functional somatic syndromes.

• Connective tissue pathology may be associated with functional somatic syndrome.

Abstract

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.

Introduction

The functional somatic syndromes (FSS) are a group of chronic disorders with a range of largely somatic syndromes that lack an accepted organic cause [1]. Notable examples are fibromyalgia, chronic fatigue syndrome (CFS) and irritable bowel syndrome [[1], [2], [3], [4]]. Though these conditions span different body systems, they share several features – i) their causes are uncertain and believed to be multifactorial [5], one factor being the psychological; ii) they are more common in young females [1,4]; iii) they have overlapping signs and symptoms [4] and iv) they have similarities with regards to the therapies to which they respond [4]. These common features have led some to argue that FSS may be manifestations of the same disease in different organ systems [4].

The aetiology of FSS constitute a significant gap in current medical knowledge. Despite high prevalence and involving significant deterioration in function and quality of life [4], FSSs pose substantial difficulties in accurate diagnosis and effective treatment [4,6,7]. A rational approach to developing better therapies for FSSs should begin with understanding their underlying causes. Hypermobile joints are one possible aetiological factor in FSS, either directly or, perhaps more likely, by the underlying connective tissue disorder which causes the hypermobility.

Joint hypermobility (JH) is a connective tissue phenotype characterised by joint laxity with an increased range of joint movement [8]. One common scale for assessing JH, for example, the Beighton criteria, assesses passive dorsiflexion of the little fingers beyond 90°, passive apposition of the thumbs to the flexor aspects of the forearm, hyperextension of the elbows to beyond 10°, hyperextension of the knees to beyond 10°, and forward flexion of the trunk with knees fully extended so that the palms of the hands rest flat on the floor, with 4 or more items (measuring each limb separately) indicating JH [9]. JH is the common feature of heritable connective tissue disorders including benign joint hypermobility syndrome (JHS), Marfan syndrome and Ehlers-Danlos syndrome [8]. However, asymptomatic JH in the absence of other connective tissue disorders is benign and not uncommon in the general population, with a higher prevalence in females, younger age groups and certain ethnicities (Asian, African) [8,10].

In recent decades, an association has been noted between JH and various FSSs [[11], [12], [13]]. The relevance of these findings is yet to be fully elucidated. Despite the associations being first reported more than 20 years ago [14], there have been no systematic reviews published to date. Here we reviewed the relevant literature for studies containing primary data describing the relationship between JH and these specific conditions.