The impact of cost sharing on adherence to ibrutinib for patients with diffuse large B-cell lymphoma
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Purpose: Nonadherence with ibrutinib, an oral treatment for diffuse large B-cell lymphoma (DLBCL), has been associated with disease progression. We examined the relationship between out-of-pocket (OOP) ibrutinib costs and adherence to ibrutinib among new users with DLBCL. Patients and Methods: We conducted a retrospective study using MarketScanÂ® commercial and Medicare supplemental claims to identify adults with DLBCL who initiated ibrutinib therapy between October 1, 2015 and December 31, 2018 with > 6 months of insurance coverage before and after initiation. Primary outcomes were adherence (proportion of days covered [PDC] > 80%) and persistence at 180 days. We used multivariable logistic regression to estimate the odds of adherence and persistence at 180 days for patients with zero, low (below median of non-zero OOP costs) and high (above median of non-zero OOP costs) OOP costs. Results: A total of 113 patients were included in the study. Monthly OOP costs for ibrutinib averaged $245 (median: $26, range: $0-$3765), and the mean PDC for ibrutinib was 67%. The odds of ibrutinib adherence trended lower for patients with higher OOP costs (adjusted odds ratio [aOR]: 0.8; 95% CI: 0.5, 1.3) following initiation, although findings failed to reach statistical significance. The odds of ibrutinib persistence at 180 days were similar across OOP cost groups (aOR: 1.0, 95% CI: 0.6-1.7). Conclusion: Patients with higher OOP costs may be more likely to be nonadherent to ibrutinib. Persistence with ibrutinib was similar across OOP cost categories. Further research with larger sample sizes is warranted to evaluate this important relationship.