Does disease activity at start of biologic therapy influence work-loss in RA patients?

Methods. We identified all RA patients aged 20-63 years in the Swedish Biologics Register who started their first biologic 2007-09 with high disease activity (DAS28 > 5.1; n = 868) or moderate disease activity (DAS28 3.2-5.1; n = 854). Work days lost, defined as sick leave and disability pension days from the Swedish Social Insurance Agency, were assessed over 5 years after first bio-start. We estimated between-group mean differences adjusted for age, sex, calendar year, education level, disease duration, comorbidities and work-loss the month before bio-start. Results. During 5 years after anti-TNF start, mean monthly work days lost declined from 16.0 to 9.2 (42%; P <0.001) in patients with high disease activity at baseline and from 12.0 to 7.2 (40%; P <0.001) in patients with moderate disease activity, with no between-group difference (adjusted mean difference 0.81; 95% CI - 0.44, 2.05). Accumulated 5-year work-loss was, however, higher in the high activity group (724 vs 548 days; adjusted mean difference 70; 95% CI 20, 120), but after stratification on baseline disability pension status, no differences in accumulated work-loss were detected. Conclusion. Substantial work-loss was seen in both patients with high and patients with moderate disease activity at anti-TNF start, with a 5-year decline in mean monthly work days lost by similar to 40% in both groups and no between-group difference. Accumulated work-loss over 5 years was higher in the high-activity group, which may be explained by differences in baseline disability pension status