P038 A psychometric evaluation of the Musculoskeletal Health Questionnaire (MSK-HQ): validation and sensitivity to change in inflammatory arthritis

Abstract

Abstract Background/Aims The Musculoskeletal Health Questionnaire (MSK-HQ) is a patient-reported outcome measure developed for use across the spectrum of musculoskeletal diseases. This study assesses the validity of the MSK-HQ. Specifically, it analyses convergent validity, construct validity, reliability and sensitivity to change in inflammatory arthritis in a national prospective cohort, with a minimum clinically important difference (MCID) defined. Methods The study sample included patients recruited to the National Early Inflammatory Arthritis Audit (NEIAA) between May 2018 and March 2020, with a diagnosis of inflammatory arthritis, returning a baseline PROM with at least half of the MSK-HQ items completed. Patients also completed PROMs at 3 and 12 months, contemporaneously to their clinic visits. Convergent validity was assessed in relation to the Health Assessment Questionnaire (HAQ)-II, Patient Health Questionnaire (PHQ)-4 and Disease Activity Score (DAS)-28. Construct validity was assessed using confirmatory factor analysis. Due to lack of an appropriate anchor, MCID was estimated based on two estimates for reliable change: standard error of the measurement (SEM) and one-third of a standard deviation (SD). Results A total of 13,129 patients were recruited to NEIAA, of whom 5,106 met the inclusion criteria. Of these 73% had rheumatoid arthritis, 13% psoriatic arthritis, 2% axial spondyloarthritis, and 12% undifferentiated arthritis. The MSK-HQ total score was approximately normally distributed, without floor or ceiling effects. The MSK-HQ correlated well with the HAQ-II (r = -0.79), PHQ-4 (r = -0.66) and moderately with the DAS-28 (r = -0.42). A unidimensional structure for the MSK-HQ was confirmed only when items 12 and 13, corresponding to disease understanding and self-efficacy, were excluded. The factor structure was found to be equivalent across disease subtypes with no major indications for differential item functioning. The MSK-HQ total score demonstrated good sensitivity to change with baseline to 12-month change having a large effect size (standardised response mean 1.01; 95%CI 0.95 to 1.07). This change compared well against the DAS-28 (-1.23; 95%CI -1.29 to -1.17) and was stronger than the HAQ-II (-0.62; 95%CI -0.68 to -0.56) and PHQ-4 (-0.57; 95%CI -0.63 to -0.51). MCID for the overall sample was 3.9 based on SEM and 3.6 assessed with one-third of an SD, both rounding to an integer of 4-points across the inflammatory arthritis subtypes. Conclusion This study provides evidence for the validity and sensitivity to change of the MSK-HQ in patients with inflammatory arthritis. In these patients, a change of more than 4 units is likely to be clinically meaningful. The MSK-HQ has high convergent and construct validity and is sensitive to change, providing a valuable tool for clinical care and research studies. Disclosure N. Arumalla: None. J. Galloway: Consultancies; AbbVie, Celgene, Chugai, Galapagos, Gilead, Janssen, Lilly, Pfizer, Roche and UCB. J. Ledingham: Other; BSR trustee. T. Garrood: None. S. Norton: None.