OBJECTIVES

Prior research has shown that racial disparities exist in cost and outcomes associated with chronic diseases such as Rheumatoid Arthritis (RA), but the nature of such disparities are not always understood. The objective of this study was to determine if medication adherence to traditional disease modifying anti-rheumatic drugs (DMARDs) is a mediator of the relationship between race/ethnicity and healthcare cost in patients with RA.

METHODS

Participants of the 2015 Medical Expenditure Panel Survey (MEPS), who reported RA and use of traditional DMARDs were included in the study. Adherence to DMARDs was captured using medication possession ratio (MPR). Direct medical costs attributed to RA were estimated from inpatient stays, office-based visits, outpatient visits, emergency room visits, and the use of prescription medications. Covariates were identified from the MEPS data based on the Andersen's Behavioral Model of Health Services Use. Generalized linear models were performed to determine the presence of mediation using the Barron and Kenny approach.

RESULTS

A total of 119 eligible individuals, representing 1,360,803 individuals were included in this study. The sample included 76% females, 75% Caucasians, 38% over the age of 65 years, and 84% reporting at least one comorbidity, with a mean family income of $61,323. The mediation analysis showed that after controlling for covariates, race was significantly associated with direct medical costs (Estimate = 0.96; SE = 0.26; p < 0.05), and but not medication adherence (Estimate = 0.033; SE: 12; p > 0.05). Medication adherence was significantly related to medical costs (Estimate = 0.40; SE: 0.14; p < 0.05).

CONCLUSIONS

Adherence to DMARDs was not found to be a mediator of the relationship between race/ethnicity and healthcare cost. Further analysis needs to be conducted to explore the mediators of racial disparities in overall medical costs among patients with RA.