An Examination of Work Instability, Functional Impairment, and Disease Activity in Employed Patients with Rheumatoid Arthritis

Objective. TO evaluate the relationship between the Disease Activity Score 28-joint count (DAS28), Health Assessment Questionnaire (HAQ), and Rheumatoid Arthritis-Work Instability Scale (RA-WIS); and to define thresholds for clinical assessments associated with moderate to high RA-WIS. Methods. Employed patients with RA were evaluated using DAS28, HAQ, and RA-WIS during routine clinic,. Relationships between these assessments were evaluated by simple correlation. Multiple linear regression modeling was performed using RA-WIS as an outcome variable and HAQ, DAS28, age, sex, occupation, and disease duration as input variables. Receiver-operating characteristic curves were then formulated to determine optimal DAS28, and HAQ cutoff points for RA-WIS >= 10, along with the odds ratio (OR). Results. Ninety patients with RA completed the RA-WIS, which was moderately correlated with DAS28 (r = 0.53) and HAQ (r = 0.66). Fifty-four percent of RA-WIS was explained by DAS28 (p = 0.002), HAQ (p = 0.001), and sex (p = 0.04). A DAS28 of 3.81 and HAQ of 0.55 were clinically important thresholds. High DAS28 and HAQ were associated with high RA-WIS (ORDAS 14.17, ORHAQ 25.13, ORDAS+HAQ 29.9). Conclusion. Functional impairment and disease activity significantly and independently contributed to patient-perceived work instability risk. (First Release Jan 15 2009; J Rheumatol 2009; 36: 225-30; doi :10.3899/jrheum.071001)