Identifying the association between health care resource utilization and switching of biologics in rheumatoid arthritis
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Objectives: To identify the predictors of switching from the first biologic to a second biologic in rheumatoid arthritis (RA) patients newly initiated on biologic treatments. Methods: Adult RA patients (18-64 years old) initiated on adalimumab, etanercept, infliximab, certolizumab, golimumab, abatacept, rituximab, tocilizumab, or anakinra between 2009 and 2011 were identified using a commercial claims database. Switching patterns were examined within one year after biologic initiation using descriptive statistics. Health care resource utilization (HCRU) variables (the number of 30-day supplies for steroid and DMARDs, and the claim counts for RA-related outpatient visits, radiographic, laboratory, intra-articular injections, rehabilitation, and surgical procedures) were assessed within one year prior to the switch date for switchers or the end of the study period for non-switchers. Pairwise comparisons of patient characteristics and HCRU variables were conducted using t-tests, Mann-Whitney U tests, and Chi-squared tests. Multiple logistic regressions were used to identify HCRU predictors of switching. Results: A total of 12,370 patients were included in the analysis. The switch rate within one year after biologic initiation was 18.4%, and the median time to switch was 181 days. More females switched compared to males (19.2% vs. 15.9%, p<.001). Switch rates were also higher in patients started on anti-TNFs compared to non-anti-TNFs (19.2% vs. 12.0%, p<.001). Furthermore, switch rates were highest in patients started on golimumab (21.0%) and were lowest in patients started on rituximab (4.8%). Overall, switchers had significantly higher rates and quantities of RA-related HCRU than non-switchers, except in the use of surgical procedures. Logistic regression models revealed that all the HCRU variables were significant predictors of switching, and patients on infliximab, abatacept, tocilizumab, and rituximab had significantly lower odds of switching than patients on etanercept. Combination therapy with DMARDs was also significantly associated with lower odds of switching. Conclusion: Switching of biologics is common in RA patients initiated on biologic therapy. There are marked differences in demographic characteristics and HCRU patterns between switchers and non-switchers. This study demonstrates that patterns of RA-related HCRU can be used to predict switching and thus can potentially serve as useful measures of treatment ineffectiveness.