Validity and interpretability of the QuickDASH in the assessment of hand disability in rheumatoid arthritis

Objective of this study is to evaluate the construct validity and the interpretability of the shortened Disability of Arm, Shoulder and Hand Questionnaire (QuickDASH) in the assessment of rheumatoid arthritis (RA) hand disability. Consecutive RA patients were assessed through the QuickDASH and other function and disease activity indices, respectively, the Health Assessment Questionnaire-Disability Index (HAQ-DI) and the Recent-Onset Arthritis Disability questionnaire (ROAD). For each patient were evaluated the tender and swollen 28-joints counts. Interpretability was defined determining cut-off points of impairment in accordance to the Simplified Disease Activity Index (SDAI) definition of disease activity states. A total of 440 patients (89 men and 351 women, mean age of 57.0 ± 12.7 years) were enrolled. Following the SDAI definition, 98 patients (22.3%) resulted in REM, 115 subjects (26.1%) in LDA, 74 patients (16.8%) in MDA, and 153 subjects (34.8%) in HDA. Mean QuickDASH differed significantly between patients classified as remission (REM), low disease activity (LDA), moderate disease activity (MDA), or high disease activity (HDA) (p < 0.001). High correlations were found comparing QuickDASH to composite indices of disease activity and of physical health function: of special interest are the correlations between the comparable dimension of the QuickDASH and the ROAD Upper Extremity Function (rho = 0.876; p < 0.001). The cut-off points for functional categories (SDAI categories as external criterion) resulted: no impairment ≤ 13, 13 < low impairment ≤ 18.5, 18.5 < moderate impairment ≤ 31.5, and high impairment > 31.5. QuickDASH is useful in clinical practice, for its ease of administration, and positively correlates with the disease activity. It may be a surrogate for evaluating upper extremity impairment, disability index and disease control in RA patients.