Background/Purpose: Despite the advances in treatment of rheumatoid arthritis (RA), many patients do not achieve remission or full physical functioning. We have previously shown that patients with RA have a significantly higher prevalence of functional disability (FD) than non-RA subjects across RA disease duration, age and calendar time. However, the pattern of improvement or worsening of functional status in RA vs non-RA patients over time has not been studied. We aimed to assess time spent in FD and transition probability between different levels of FD in patients with RA vs the non-RA subjects after RA incidence/ index date.

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 non-RA subjects from the same area matched by age and sex. Index date was RA incidence date for RA subjects and incidence date of the matching RA patient for non-RA subjects. Activities of Daily Living (ADL) were recorded annually since 1999 based on patient provided information about performing 6 ADLs without assistance: feeding oneself, dressing, using the toilet, bathing, walking and housekeeping. FD was defined as having difficulty with ≥1 of the 6 ADLs. Changes in the number of disabilities were considered to be state transitions. Multi-state modeling was used to estimate the probability of transitioning between FD states, with death as a final state. Cox models of multistate data were used to assess the risk of transition with 95 percent confidence intervals (CI) between the levels of FD, adjusting for age, sex, calendar year of index, smoking, and obesity.

Results: A total of 558 patients with RA (mean age 55.4 years, 71% females, 64% RF/CCP positive) and 457 non-RA subjects (mean age 56.5, 70% females) completed 6,594 questionnaires (3,875 RA and 2,719 non-RA) from 1/5/1999 to 1/5/2018 on or after index date. Figure 1 shows probability of FD in RA vs non-RA patients after the index date. In the first 15 years of disease, patients with RA expect to spend 10.1 years without FD and 1.7 years with 1 FD vs 11.6 years (p< 0.001) and 0.9 years (p< 0.001) in non-RA subjects, respectively. Probability of no FD at index is 78% in RA and 92% in non-RA. By 10 years after index date, probability of no FD in RA is 65%; probability of 1 disability 11%; 2 disabilities 6%, and >3 disabilities 1%, compared to 73%; 7%; 5% and 1% in the non-RA subjects, respectively. Risk of transitioning from no FD to FD is significantly higher in RA vs non-RA subjects: Hazard Ratio (HR) 2.4; 95%CI 1.9-3.0. Patients with RA and non-RA subjects have similar risk of returning from FD to no FD (HR 1.2; 95%CI 0.93-1.6). Results did not differ by RF/CCP status.

Conclusion: Patients with RA have a significantly higher probability of any level of FD over RA disease duration, less time spent with no FD, and a 2-fold increased risk of transitioning from no FD to FD, but a similar risk of transitioning back to normal functional status during RA disease course compared to their non-RA counterparts. Our findings suggest that in the era of advanced therapeutics for RA disease management, FD remains an area of ongoing concern, leaving an ample room for improvement of functional outcomes in RA.

Figure 1. Probability of functional disability in 558 rheumatoid arthritis (RA) versus 457 non-RA patients after RA incidence/ index date

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-point-of-no-return-functional-disability-in-patients-with-rheumatoid-arthritis-versus-the-general-population-results-from-a-population-based-cohort-study/