Background/Purpose: Despite the advances in treatment of rheumatoid arthritis (RA) over the recent decades, many patients with RA do not achieve remission or full physical functioning. Changing burden of functional disability (FD) in patients with RA has not been widely studied. We aimed to assess the prevalence of patient-reported FD in RA compared to subjects without RA over RA disease duration, age range and calendar time, and to define the effect of rheumatoid factor/ anti-cyclic citrullinated peptide (RF/CCP) positivity on the prevalence of FD in patients with RA.

Methods: This retrospective population-based cohort study included residents of a geographical area who met 1987 ACR criteria for RA in 1999-2013 and a cohort of subjects without RA from the same area matched by age and sex. Index date for each non-RA subject corresponded to incidence date of the matching patient with RA. Activities of Daily Living (ADL) were recorded annually over the past 20 years based on patient provided information about performing six ADLs without assistance including feeding oneself, dressing, using the toilet, bathing, walking and housekeeping. FD was defined as having difficulty with ≥1 of the six ADLs. Analyses were performed using age-, sex- and disease duration adjusted logistic regression models with random subject effects to account for multiple measures per patient.

Results: Five hundred eighty-six patients with RA (mean age 55 years, 70% females, 374 (64%) RF/CCP positive) and 531 non-RA subjects (mean age 56, 70% females) have completed 7,446 questionnaires (4,301 RA and 3,145 non-RA) from 1/5/1999 to 1/5/2018 on or following their RA incidence/index date. The prevalence of FD was significantly higher in the RA vs non-RA subjects, starting at RA incidence/index date (26% in RA vs 11% in non-RA subjects, p<0.001), with persistent excess in prevalence over the entire follow-up time. Patients with RA compared to the non-RA subjects had at least a 15%-excess in the proportion of FD at any given age up to the 8-9^th decade of life. The prevalence of FD overall was similar in RF/CCP positive vs negative patients with RA (p=0.67). However, there was a significant interaction between RF/CCP positivity and disease duration (p=0.027; Figure), suggesting that the prevalence of FD over disease duration is increasing in patients with RF/CCP and declining in those negative for RF/CCP.

Conclusion: Patients with RA have a significantly higher prevalence of FD over RA disease duration and across the age-range compared to their non-RA counterparts. RF/CCP positive patients are disadvantaged with an increasing burden of FD over their RA disease duration, while RF/CCP negative patients experience decline in FD, suggesting that additional vigilance and measures may be needed in management of patients with positive RF/CCP to help improve their FD profile.  

Figure.