Work disability among two cohorts of women with recent-onset rheumatoid arthritis: a survival analysis

To analyze factors associated with leaving employment among women with newly diagnosed rheumatoid arthritis (RA).

Women with RA were recruited from a national sample of rheumatologists in 1987 and 1998. Inclusion criteria were RA diagnosis <18 months earlier, age >or=18 years, and no other disabling health condition. The 1987 and 1998 cohorts comprised 48 and 91 women, respectively. Data were collected by telephone for 4 years. Survival analysis was conducted using Kaplan-Meier curves and a proportional hazards generalized linear model to assess whether the time to stopping work differed between the cohorts and to identify baseline predictors and time-varying covariates of leaving work.

Most patients were age <50 years, married, had >12 years of education, and were white. Fifteen patients (31%) in the 1987 cohort and 24 patients (26%) in the 1998 cohort stopped working in the observation periods. Kaplan-Meier survival curves for each cohort were not significantly different. Multivariate analyses demonstrated that married women (P = 0.03) and those with joint deformities (P = 0.00) were more likely to stop working. A significant flares by cohort interaction (P = 0.01) indicated that, in comparison with patients in the 1998 cohort, those in the 1987 cohort with <2 disease flares had the lowest risk of stopping work and those with >or=2 flares had the greatest risk.

Unexpectedly, the cumulative rate of stopping work among women in the 1998 study did not differ from that among women diagnosed >16 years earlier. However, disease flares greatly affected employment in the 1987 but not the 1998 cohort, possibly indicating that newer medications were effective in maintaining functional status among those with more severe disease activity, measured by number of flares, in the 1998 group.