Assessment of systemic joint laxity in the clinical context: Relevance and replicability of the Beighton score in chronic fatigue

BACKGROUND: Persistent symptoms in patients with systemic joint laxity (SJL) are often equivalent with complications. Screening for SJL is an important part of the assessment of musculoskeletal phenotype. The common measuring tool, the Beighton score (BS), still has unclear evidence. OBJECTIVE: To assess the Beighton score in a clinical context for (1) ability to classify SJL as absent or present (criterion validity), and (2) interrater reliability (physician-physiotherapist), for a dichotomous cut-off (yes/no), as well as for interpretation in categories (no, some, clear SJL). METHODS: This real-world observational study included 149 consecutive patients seeking secondary care for investigation of possible myalgic encephalomyelitis/chronic fatigue syndrome. Assessment was done during a routine examination. Data were evaluated with Cohen’s kappa and Spearman’s rho. RESULTS: BS criterion validity showed poor agreement with the assessment of SJL: percentage agreement was 74 % and kappa 0.39 (3-cut level), 73 % and kappa 0.39/0.45 (4-/5-cut level). The best interrater reliability was moderate (rho 0.66) for interpretation in categories. CONCLUSIONS: The BS alone was not a reliable proxy for SJL and should be supplemented with a targeted history. Nevertheless, its interrater reliability was acceptable, and the categorised score appears to have greater clinical relevance than the dichotomous score.