OBJECTIVE: To determine whether multimorbidity is associated with treatment changes and achieving target disease activity thresholds in patients with active rheumatoid arthritis (RA).
METHODS: We conducted a retrospective cohort study of adults with active RA within the Rheumatology Informatics System for Effectiveness (RISE) registry. Multimorbidity was measured using RxRisk, a medication-based index of chronic disease. We used multivariable logistic regression models to assess the associations of multimorbidity with the odds of initiating a new DMARD in active RA and, among those initiating a new DMARD, the odds of achieving low disease activity or remission.
RESULTS: We identified 15,626 (RAPID3 cohort) and 5,733 (CDAI cohort) patients with active RA, of which 1,558 (RAPID3) and 834 (CDAI) initiated a new DMARD and had follow-up disease activity measures. Patients were middle aged, female and Caucasian predominant, and on average received medications from 6-7 RxRisk categories. Multimorbidity was not associated with new DMARD initiation in active RA. However, a greater burden of multimorbidity was associated with lower odds of achieving treatment targets (per 1-unit RxRisk OR 0.95 [95% CI 0.91-0.98] RAPID3 cohort; OR 0.94 [95% CI 0.90-0.99] CDAI cohort). Those with the highest burden of multimorbidity had the lowest odds of achieving target RA disease activity (OR 0.54 [0.34-0.85] RAPID3 cohort; OR 0.65 [0.37-1.15] CDAI cohort).
CONCLUSIONS: These findings from a large, real-world registry illustrate the potential impact of multimorbidity on treatment response and indicate that a more holistic management approach targeting multimorbidity may be needed to optimize RA disease control in these patients.