BEYOND BONES - THE RELEVANCE OF VARIANTS OF CONNECTIVE TISSUE (HYPERMOBILITY) TO FIBROMYALGIA, ME/CFS AND CONTROVERSIES SURROUNDING DIAGNOSTIC CLASSIFICATION: AN OBSERVATIONAL STUDY

ABSTRACT Objectives To understand the relevance of symptomatic hypermobility and related connective tissue variants to the expression of symptoms in Fibromyalgia and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). The study further tested if specific subfactors within the diagnostic classification of hypermobility predict clinical presentations. Design We report part of a larger case-control study exploring mechanisms of chronic pain and fatigue in Fibromyalgia and ME/CFS ( https://doi.org/10.1186/ISRCTN78820481 ) Setting an NHS Clinical Research Facility. Participants A subsample of 87 participants were assessed for symptomatic hypermobility by a trained clinician: 63 presented with a clinical diagnosis of either Fibromyalgia and or ME/CFS confirmed at screening; 24 participants were confirmed as healthy controls. Main outcome measures 1) Brighton Criteria for joint hypermobility syndrome and 2017 hEDS diagnostic criteria. 2) ACR 2010 Diagnostic Criteria for Fibromylagia and Canadian and Fukada diagnostic criteria for ME/CFS. 3) Self report measures of subjective pain, fatigue and interoceptive sensibility. Results Twenty of the 63 patients (32%) presented with a clinical diagnosis of Fibromyalgia; 24 (38%) with a clinical diagnosis of ME/CFS and 19 (30%) with dual diagnoses of fibromyalgia and ME/CFS. After evaluation using clinical research tools, 56 patients (89%) met ACR diagnostic criteria for fibromyalgia; 59 (94%) Canadian Criteria for ME/CFS; and 61 (97%) Fukada Criteria for ME/CFS. After research evaluation 52 patients (85%) in fact met diagnostic criteria for Fibromyalgia and ME/CFS on all three sets of tools (ACR, Canadian, Fukada). In addition, 51 patients (81%) and 9 (37.5%) healthy controls met Brighton Criteria for joint hypermobility syndrome and 11 (18%) and 2 (8%) of patients and controls respectively, on the 2017 hEDS criteria. Of these patient participants with symptomatic hypermobility only 12 (23.5%) had received a prior diagnosis of hypermobility. Across all participants meeting Brighton Criteria, 13 (22%) also endorsed a hEDS diagnosis. Membership of the patient group was predicted by meeting the Brighton Criteria for joint hypermobility syndrome (p=<0.001, OR 7.08, 95%CI 2.50 – 20.00), but not by meeting the hEDS criteria. The historical, rather than current Beighton score correlated with; 1) total pain reported on the McGill Pain Questionnaire (short form), (r= 0.25, n= 73, p=0.03); 2) Widespread Pain Index (derived from ACR diagnostic criteria) (r=0.26, n= 86, p=0.01); 3) ACR symptom severity (r=0.27, n=85, p=0.01); 4) Fatigue Impact (r=0.29, n=56, p=0.28); and 5) interoceptive sensibility (r=0.30, n=56, p=0.02). Conclusions Symptomatic joint hypermobility is relevant to symptoms and diagnosis in Fibromyalgia and ME/CFS. These conditions are poorly understood yet have a considerable impact on quality of life. Further work is needed to determine the prevalence of hEDS within the general population and define the critical clinical dimensions within symptomatic hypermobility. It is important to note the high rates of mis/underdiagnosis of symptomatic hypermobility in this group. Moreover, we need to clarify the role of variant connective tissue in dysautonomic and inflammatory mechanisms implicated in the expression of pain and fatigue in fibromyalgia and ME/CFS. Our observations have implications for diagnosis and treatment targets. Study registration ISCRTN78820481

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