Rates, factors, reasons, and economic impact associated with switching in rheumatoid arthritis patients newly initiated on biologic disease modifying anti-rheumatic drugs in an integrated healthcare system.

Objectives To identify how many RA patients newly-initiated on bDMARD therapy switch to another bDMARD during the first year of treatment; to evaluate the factors and reasons associated with bDMARD switching; and to compare the RA-related healthcare resource utilization (HCRU) and costs between switchers vs non-switchers during the post-index period. Methods A retrospective cohort study was conducted in RA patients using the Kaiser Permanente Southern California (KPSC) database with the study time period of January 1, 2007 to December 31, 2012. The index date was defined as the date of the first bDMARD prescription. Patients had to have continuous membership eligibility with drug benefit and no prior history of bDMARD during the 24 months prior to the index date. bDMARD switching was defined as a different bDMARD claim during post-index. A multivariable logistic regression model was used to evaluate factors associated with switchers vs non-switchers. Chart notes were reviewed to evaluate reasons for switching from index bDMARD. RA-related HCRU use and costs were evaluated using a generalized linear model (GLM) with gamma distribution and log link function. Results Two hundred and fifty-one patients (12%) switched from their index bDMARD to a different bDMARD during the post-index period. bDMARD switchers were more likely to be female, of Asian/Pacific race, younger than ≤65 years of age, overweight, CCI score ≤2, initiating etanercept or adalimumab, and have a commercial insurance plan compared to non-switchers. Reasons for switching were related mostly to lack or loss of efficacy (∼51%); bDMARD switchers had overall mean adjusted RA related total costs that were 25% higher (p = 0.04) compared to non-switchers. Conclusion It is important for RA patients to receive appropriate therapy and consider bDMARD with different mechanisms of action to decrease subsequent switching, and decrease overall RA related costs as shown in this study.