OBJECTIVES

With increased use of biologic disease-modifying antirheumatic drugs (bDMARDs), there is a need to analyze the impact of comorbidities on RA costs to inform new payment methodologies. We evaluated RA-related outpatient treatment costs in a community practice cohort.

METHODS

Using electronic medical records from 8 large mid-Atlantic rheumatology practices, adult patients with RA (International Classification of Diseases 9^th revision (ICD-9) 714, ICD-10 M05, M06) who initiated or switched to a new bDMARD during April 2016-March 2018 were selected and followed for 12 months. We accounted for cost of care provided by the rheumatology practices including evaluation & management, DMARDs, bDMARDs, steroids, drug administration, and labs. Annual costs were standardized to 2019 USD. Comorbidities were assigned based on reported medications. Differences between groups were assessed using t-test for continuous variables and chi-square test for categorical; costs were assessed using propensity score matching (PSM) and generalized linear models (GLM) with gamma distribution and log link function.

RESULTS

Of 2140 patients, 1744 (82%) had at least 1 comorbidity. Compared to patients without comorbidities, patients with comorbidities were older (mean age 60.5 vs 50.7, p<0.001), more likely to be white (73% vs 67%, p<0.001), female (80% vs 73%, p=0.004), and Medicare-insured (46% vs 25%, p<0.001). Before accounting for demographics, patients with comorbidities had higher total outpatient RA costs (56,405 vs 49,298, p=0.021). After accounting for differences in demographics using GLM, there was no difference in costs (52,209 vs. 48,484, p=0.144). After PSM (350 patients per group matched without replacement by age, race, payer, and gender), there was no difference in costs (47,697 vs 47,612, p=0.983).

CONCLUSIONS

Among RA patients treated with bDMARDs in a community cohort, the majority had comorbidities. After accounting for demographics, annual outpatient RA costs were not different between patients with vs without comorbidities.