Current risk factors for work disability associated with rheumatoid arthritis: recent data from a US national cohort

Abstract

Objective: To explore, using recent data, whether and how risk factors for rheumatoid arthritis (RA) work disability may differ from previous studies.

Methods: Subjects were 953 individuals with RA from a US cohort who provided data semiannually over 18 months (years 2002-2005). A nested case-control design was used with matching on time of baseline data collection. All subjects were employed at baseline; cases were consistently not employed at followup, whereas controls remained employed. Hierarchical conditional logistic regression assessed the roles of demographic, RA disease, general health, and work factors as predictors of work disability. Recursive partitioning and causal modeling procedures were also used.

Results: Sample characteristics were mean age 51 years, 82% female, and 92% white. Older age (odds ratio [OR] 1.2, 95% confidence interval [95% CI] 1.1-1.4) and lower income (OR 1.7, 95% CI 1.0-2.7) predicted work disability, whereas more hours worked (OR 0.9, 95% CI 0.8-0.9) and preference to work full time (OR 0.2, 95% CI 0.1-0.4) or part time (OR 0.4, 95% CI 0.2-0.6) versus not to work were protective in the regression analysis. In recursive partitioning analyses, RA disease factors predicted work disability among older subjects, and functional limitation was the fourth most important factor. Job physical demand was not a significant or important factor.

Conclusion: In this contemporary data from a large RA cohort, older age, lower income, fewer working hours, and preference not to work were the risk factors for work disability. The impact of disease factors was limited to subjects ages >or=56 years. Job physical demand level had little impact.

Figure 1

Classification tree of employment status at followup. Boxes are final nodes. The top number is number of subjects, and the bottom number is the percentage is the dominant proportion; E = employed; NE = not employed; * = personal income from employment, range 0–1 where 1 = ≤ US median income; ^† = status considering all RA effects, where higher score = poorer status; ‡ = Health Assessment Questionnaire (HAQ) measure of functional limitation, where higher scores = greater limitations.