Work disability is a common outcome of rheumatoid arthritis (RA). Yet there have been no longitudinal, longterm, prospective studies of work disability in this illness. This 18 year longitudinal study investigates the rate of work disability, its concomitants, and its predictors, using a large series of clinical, laboratory, and self-report measures.
In 1974, a computerized database was developed for the contemporaneous entry of all patient visits. Data included clinical, laboratory, and self-report information. Patients were also assessed by mailed questionnaires at 6 month intervals. In 1994, patients with RA were interviewed in detail about lifetime work status and work disability.
Work disability was estimated to occur in 25% at 6.4 years and 50% at 20.9 years after disease onset, and most disability occurred late in the course of disease. Work disability was predicted by almost every demographic and clinical variable. Education level, body mass index (BMI), erythrocyte sedimentation rate, rheumatoid factor, pain, Health Assessment Questionnaire (HAQ) disability, and physical demands of the job were independently associated with disability. Over the course of their illness, the work disabled had a 35% reduction in family income, and had more abnormal scores for joint counts, grip strength, sedimentation rate, pain, global severity, HAQ disability, and anxiety and depression. Except for BMI, the results were essentially similar in a subset of 156 patients seen first with a disease duration of less than one year.
Work disability can be predicted by patient and work characteristics present at the first clinic visit, but it is persistent abnormalities of sedimentation rate, HAQ disability, and pain, which may be detected in longitudinal followup, that best predict work disability after work and demographic characteristics are accounted for.