Influence of age and gender on the 28-joint Disease Activity Score (DAS28) in rheumatoid arthritis

Objectives: To investigate the influence of age and gender on the components of the 28-joint Disease Activity Score (DAS28) in patients with rheumatoid arthritis (RA), and to clarify whether a high DAS28 can be equally interpreted in all age groups, independent of gender. Methods: A prospective cohort of 553 patients with RA was studied for approximately 20 years after diagnosis. The single measures of disease activity and the share of different components of the DAS28 (eg, erythrocyte sedimentation rate; ESR) were analysed and compared between three age groups (<45, 45-65 and >65 years) and per gender, using analysis of variance (ANOVA). The performance of the DAS28 and its components was explored in moderate to high and low DAS28 categories. Linear mixed model analysis was used to design the models best predicting ESR and the share of ESR. Results: ESR significantly increased with age, independent of other variables of disease activity. This increase was more pronounced in male than in female patients. Nevertheless, the share of ESR increased with age only in male patients with a low DAS28 (<3.2). If the DAS28 score was >3.2, age and gender did not have a significant effect on any components of the DAS28. C-reactive protein (CRP) and DAS28(CRP) were not influenced by age. Conclusions: A high DAS28 was found to perform equally in all age groups, in men and women, despite the elevating effect of age on ESR. In elderly men with low disease activity, remission rate could be underestimated by an elevated ESR.