Background/Purpose: Seropositivity has historically been associated with poor disease outcomes in patients with rheumatoid arthritis (RA). Seronegative RA is on the rise and is associated with higher rates of multimorbidity (i.e., 2 or more chronic conditions). However, little is known about the association between multimorbidity and RA disease activity. We aimed to assess the association between multimorbidity and RA disease flares and remission.

Methods: This retrospective, population-based study included residents of a geographically well-defined area with incident RA in 1999-2014 who fulfilled 1987 ACR criteria for RA. Flare/remission were defined using OMERACT definitions and were manually abstracted from medical records. Flare was defined as a worsening of disease requiring initiation, change, or escalation of therapy or documentation of ‘flare up’ or ‘active’ disease. Remission was defined as an absence of disease activity (e.g., ‘remission’, ‘quiescent’, ‘no activity’) and/or based on ≤1 tender/swollen joints and normal inflammatory markers. Multimorbidity at RA incidence was defined using 55 chronic conditions published previously and was categorized as MM2+ (2 or more comorbidities) or MM5+ (5 or more comorbidities). Binomial mixed models with random effects accounting for multiple visits per patient adjusted for age, sex, RA duration, seropositivity, incidence year, and smoking status were used to assess the association between flare/remission and multimorbidity.

Results: The study included 625 patients with RA (mean age 55.5 years, 70% female, 88% white, 68% seropositive, 47% current/former smokers, 40% obese). Among 7841 visits over a mean follow-up of 8.7 (SD 4.3) years, 2793 were in flare (36%) and 1929 (25%) were in remission. Multimorbidity was modestly associated with flare, but these associations did not reach statistical significance (MM2+: OR 1.22;95% CI: 0.97-1.53, p=0.08; MM5+: OR 1.16; 95%CI 0.94-1.44, p=0.16). Multimorbidity was significantly associated with decreased odds of remission for both MM2+ (OR 0.63; 95%CI 0.46-0.87, p=0.0048) and MM5+ (OR 0.64 [95%CI 0.48-0.87, p=0.0046). Seropositivity was not significantly associated with flare (OR 1.13; 95%CI 0.93-1.40; p=0.21) or remission (OR 1.00; 95%CI 0.75-1.34, p=0.99). Male sex, longer RA duration, and increased age were associated with significantly greater odds of remission and smoking at baseline was associated with significantly decreased odds of remission. RA duration, increased age, and increased year of RA index were associated with significantly lower odds of flare and current smoking with significantly increased odds of flare.

Conclusion: Patients with RA and multimorbidity were less likely to achieve remission. Multimorbidity was a stronger predictor of poor prognosis than seropositivity. These results underscore the importance of considering multimorbidity and not just seropositivity when assessing prognosis for patients with RA. Further research is needed to elucidate the underlying mechanisms of these associations (e.g., whether certain morbidities are associated with poor prognosis, or the impact of patient complexity on adherence or other issues are playing a role).

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/multimorbidity-burden-predicts-lower-likelihood-of-remission-in-patients-with-rheumatoid-arthritis/