Physical disability in patients with rheumatoid arthritis (RA) is often assessed by questionnaires. We compared the Recent-Onset Arthritis Disability (ROAD) questionnaire with the Health Assessment Questionnaire (HAQ) disability index (DI) in a cohort of RA patients. The aim of this study was to obtain information on several aspects of construct validity of these measures.
A cross-sectional multicentre study was carried out among patients with RA who were attending hospital outpatient clinics. The patient group included 196 patients partially or not responding to disease modifying anti-rheumatic drugs. For the evaluation of the psychometric properties of the ROAD in comparison with HAQ-DI this population has been compared to another cohort of 247 outpatients with RA who were participating in a long-term observational study. All patients completed the ROAD and HAQ-DI. Additional comparator composite indices of disease activity were analysed. The ROAD structural validity was first assessed using exploratory factor analysis. Concurrent validity was analysed by Spearman's correlations and cross-tabulations. Discriminant validity to distinguish patients with active and non-active disease was assessed with receiver operating characteristic (ROC) curve analysis. For agreement analysis Bland and Altman plots were calculated.
Factor analysis yielded a two-factor ROAD score that accounted for 68.74% of the explained variance in the questionnaire. The first factor, namely upper extremity function/activity daily living and work (ROAD-upper) accounted for 55.6% of the explained variance. The second factor, namely lower extremity function (ROAD-lower) accounted for 13.1% of the explained variance. Significant correlations were found between the scores of the ROAD and the other clinical variables with a high ability to measure pain and disease activity, supporting the concept of convergent construct validity. The discriminatory power of both questionnaires to assess inactive and active RA patients was good, without significant difference.
ROAD is a good alternative to the HAQ-DI for the assessment of physical disability in RA. Use of the ROAD makes it easier and less costly to collect data and reduces the burden on RA patients and should be applied in both clinical trials and routine clinical care settings.