Objective
Develop and validate a shortened version of the Valued Life Activities disability and accommodations scale (VLA) for individuals with rheumatoid arthritis (RA).
Methods
To shorten the existing VLA measure, item response theory analyses were conducted using data from 449 patients with RA. Next, the resulting 14-item shortened version of the VLA scale (S-VLA) was evaluated by structured interviews among 20 RA patients. Lastly, the S-VLA was administered to 150 RA patients along with other measures including the Health Assessment Questionnaire (HAQ) and SF-36. A random sample of 50 patients completed the S-VLA two weeks later to assess reliability. Item statistics were calculated to evaluate correlations between individual items and S-VLA total score. Correlations between the S-VLA and other measures were used to evaluate validity.
Results
Test–retest reliability was 0.91, while Cronbach’s alpha for the S-VLA was 0.95. None of the 14 items were associated with improved alpha coefficients when omitted. All items were strongly correlated with the S-VLA total score. S-VLA scores were highly positively correlated with HAQ (r=0.81; p≤0.001), patient-reported disease activity (r=0.71; p≤0.001), satisfaction with abilities (r=0.82; p≤0.001), and number of days with activity limitations (r=0.65; p≤0.001). In addition, as hypothesized, the S-VLA was inversely correlated with SF-36 Physical Component Summary score (r=−0.78; p≤0.001) and subscales: Physical Functioning (r=−0.80; p≤0.001), Role Physical (r=−0.67; p≤0.001) and Social Functioning (r=−0.72; p≤0.001).
Conclusions
The S-VLA is a short, valid, and reliable instrument that may prove useful for monitoring disability among individuals with RA.