Gout occurs in working-age people and may be associated with significant work disability. There are no longitudinal studies to examine risk factors for work disability in people with gout.
The purpose of this study was to determine the validity of the Work Instability Scale (WIS) in patients with gout and to see if baseline WIS scores predicted future work absences.
We conducted a longitudinal, cohort study with patients who had gout for less than 10 years. Sick leave over the previous 3 months was recorded by patient recall at baseline and at 12 months. Self-report health status measures and disease characteristics including C-reactive protein and serum urate were measured at baseline. Work Instability Scale scores were fitted to a Rasch model, and nonparametric statistics were used to determine associations between disease features or future sick leave and WIS scores.
One hundred seventy-six participants were recruited, and follow-up information was available for 133 (76%). The WIS instrument showed satisfactory internal, construct, and predictive validity. Participants in nonmanual occupations had lower (better) WIS scores (median, 0 vs. 5.5; P < 0.001). Only 7% of working participants reported any sick leave in the 3 months before the 12-month follow-up. Work Instability Scale scores were associated with future sick leave: a cutoff of 4.5 was found to have the best combined sensitivity (88%) and specificity (72%) for predicting at least 1 day of sick leave.
The WIS instrument can identify people with gout who have a higher risk of future work disability and might be a useful guide to targeted vocational counseling or job modification, especially in people in manual occupations. However, further research is required to confirm these findings and to refine the instrument for optimal performance in this population.