Direct Medical Expenditure Associated with Rheumatoid Arthritis in a Nationally Representative Sample from the Medical Expenditure Panel Survey

Objective: To quantify the incremental direct medical expenditure associated with rheumatoid arthritis (RA) in the US population from a payer's perspective.

Methods: A probability-weighted sample of adult respondents from the Medical Expenditure Panel Survey (2008) was used to identify a cohort of patients with RA and compared to a control cohort without RA. Annual expenditure outcomes, including total expenditure and subgroups related to pharmacy, office-based visits, emergency department visits, hospital inpatient stays, and residual expenditures were estimated. Differences between the RA and control cohort were adjusted for sociodemographic factors, employment status, insurance coverage, health behavior, and health status using a generalized linear model with log link and gamma distribution. Statistical inferences on difference in expenditures between RA and non-RA controls were based on nonparametric cluster bootstrapping using percentiles.

Results: The adjusted average annual total expenditure of the RA cohort in 2008 US dollars (USD) was $13,012 (95% confidence interval [95% CI] $1,737-$47,081), while that of the control cohort was $4,950 (95% CI $567-$17,425). The incremental total expenditure of the RA patients as compared to non-RA controls was $2,085 (95% CI $250-$7,822). RA patients also had a significantly higher pharmacy expenditure of $5,825 (95% CI $446-$30,998) that was on average $1,380 (95% CI $94-$7,492) higher as compared to the controls. The summated total incremental expenditure of all RA patients in the US was $22.3 billion (2008 USD).

Conclusion: RA exerts considerable incremental economic burden on US health care, which is primarily driven by the incremental pharmacy expenditure.