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 (RAWIS); 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 clinics. 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 >or= 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 (OR(DAS) 14.17, OR(HAQ) 25.13, OR(DAS+HAQ) 29.9). CONCLUSION: Functional impairment and disease activity significantly and independently contributed to patient-perceived work instability risk.