Background/Purpose: The involvement of multiple joints is common in osteoarthritis (OA), often referred to as generalized OA (GOA). Individuals with GOA typically suffer from limitations of both upper and lower extremity function. However, existing instruments measuring functional limitations in OA focus on a specific localization; limiting their use in GOA. We hypothesized the Health Assessment Questionnaire Disability Index (HAQ-DI), originally developed for inflammatory arthritis, to be appropriate to measure functional limitations in GOA. Therefore we evaluated the measurement properties (content validity, construct validity and reliability) of the HAQ-DI in patients with GOA.
Methods: Data were used from a randomized clinical trial comparing the effectiveness of two multidisciplinary treatment program for patients with GOA. 137 patients completed a standardized set of questionnaires before and directly after treatment. The measurement properties of the HAQ-DI were assessed according the Consensus Based Standards for the Selection of health Status Measurement Instruments Checklist. Floor and ceiling effects for each HAQ-DI category at baseline were considered present if >15% of patients scored the worst (3) or best (0) possible score. For the content validity, 17 health professionals experienced with GOA were asked to judge the relevance of each HAQ-DI item. Construct validity was assessed by computing associations (Pearson r) between HAQ-DI scores and scores on other clinical (un)related measures. Reliability was assessed by Cronbach’s alpha and intra-class correlation coefficient (ICC). The minimal important change (MIC) score was calculated using an anchor based method.
Results: Of 137 patients (mean age 60(SD 8) years; (85%) female), 93% reported to have complaints in both the upper and lower extremities. Floor and ceiling effects were present: 20%-30% of patients reported the best possible score on the HAQ-DI categories eating, dressing and gripping; 16% reported the worst possible score on the category hygiene. The content validity was questionable since according to the health professionals the HAQ-DI encompasses 9 (out of 20) activities that are not relevant or too easy to perform for GOA patients. Construct validity was rated positive given the moderate to strong associations with related constructs and weak associations with unrelated constructs. Cronbach’s alpha was 0.90, confirming internal consistency and the ICC was 0.81, reflecting good reliability. The MIC was 0.25 points and the smallest detectable change was 0.60 indicating that important changes cannot be distinguished from measurement error in individuals.
Conclusion: The HAQ-DI showed a good construct validity and reliability to measure functional limitations in patients with GOA. Given the unsatisfactory content validity, we recommend an update of the HAQ-DI items when using the HAQ-DI in future clinical practice and research focusing on functional limitations in GOA. This update might also be worthwhile for RA and all other rheumatic diseases.
Disclosure:
N. Cuperus,
None;
E. A. M. Mahler,
None;
T. Vliet Vlieland,
None;
T. Hoogeboom,
None;
C. H. M. van den Ende,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/measurement-properties-of-the-health-assessment-questionnaire-disability-index-haq-di-in-patients-with-generalized-osteoarthritis-goa/