Background: The assessment of generalized joint hypermobility is difficult due to differences in classification methods and in the performance of joint mobility assessment. The primary aim was to evaluate the validity of the self-reported five-part questionnaire, 5PQ, for identifying generalized joint hypermobility using the Beighton score as reference test. The secondary aim was to describe how joint angles measured in degrees included in the Beighton score varied in different cut-off levels in the self-reported 5PQ and the Beighton score.
Methods: A cross-sectional validity study with a total of 301 women in early pregnancy, mean age of 31 years, were included in the study. The participants answered the self-reported 5PQ before the joint angles were measured. To standardize the joint mobility measurement, a structural protocol was used. The sensitivity, specificity, receiver operating characteristic curve, area under curve, positive- and negative predictive value, positive likelihood ratio and Spearman's rank correlation between the self-reported 5PQ ≥ 2 and the Beighton score ≥ 5 were used as main outcome measures in the validity analyses. Joint angles, measured in degrees, were calculated with means in relation to different cut-off levels.
Results: There was moderate correlation between the self-reported 5PQ and the Beighton score. The highest combined sensitivity, 84.1%, as well as specificity, 61.9%, was on 5PQ cut-off level ≥ 2, with a 38% false-positive rate, a moderate area under curve, a low positive predictive value and likelihood ratio, and a high negative predictive value. The odds of a self-reported 5PQ, cut-off level ≥ 2, among women with generalized joint hypermobility, Beighton ≥5, was low indicating a low post-test probability. The mean for all joint angles measured in degrees increased with increased cut-off levels, both in the Beighton score and in the self-reported 5PQ. However, there was a significant variation for each cut-off level.
Conclusions: There is uncertainty in identifying generalized joint hypermobility in young women using the self-reported 5PQ with a cut-off level of ≥2 when the Beighton score ≥ 5 is used as the reference test. The strength of the self-reported 5PQ is to rule-out women without generalized joint hypermobility.
Keywords: Beighton score; Diagnostic accuracy; Five-part questionnaire; Generalised joint hypermobility; Validity.