Ability of the Bristol Impact of Hypermobility questionnaire to discriminate between people with and without Joint Hypermobility Syndrome: a known-group validity study

Introduction: A number of psychometric properties of the Bristol Impact of Hypermobility (BIoH) questionnaire have previously been demonstrated, including strong concurrent validity and test–retest reliability. This study aimed to identify whether it can discriminate between those with and without Joint Hypermobility Syndrome (JHS). Methods: The wording of a small number of BIoH questionnaire items was adapted to create a generic version that asked about ‘general health' rather than ‘hypermobility'. The generic questionnaire was distributed online to university students and staff. A sampling frame was used to create age and sex-matched samples from the non-JHS respondents in the current study and a pre-existing JHS cohort. Questionnaire scores were then compared between samples. Results: 790 responses were received. 414 were excluded, mainly due to self-reported generalized joint hypermobility or a JHS diagnosis. The sampling frame was applied to the remaining non-JHS responders (n = 376) and the pre-existing JHS cohort (n = 448), resulting in 206 age and sex-matched participants in each sample. The median (IQR) BIoH scores (out of a maximum 360) were 81 (57.25) and 231.5 (74.25) in the non-JHS and JHS samples respectively (p < 0.001). There was a very strong correlation between BIoH score and the number of painful areas (r = 0.867, p < 0.001). Conclusions: The BIoH questionnaire discriminates between those with and without JHS. The median difference (151.5 points) far exceeds the smallest detectable change of 42 points previously identified. The results provide further evidence of the psychometric properties of the BIoH questionnaire and its potential to support research and clinical practice.