Healthcare resource utilization and costs of chronic lymphocytic leukemia/small lymphocytic lymphoma patients who relapse or are refractory to ibrutinib

<b>Aim:</b> Evaluate healthcare resource utilization (HRU) and costs in chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) who relapsed or are refractory to (R/R) ibrutinib.<b>Methods:</b> All-cause and CLL/SLL-related HRU and healthcare costs were evaluated in adult patients with CLL/SLL who received ibrutinib (2/2014-3/2020) as single-agent or combination therapy and discontinued/switched to another antineoplastic agent (R/R) vs. all other (non-R/R) ibrutinib users.<b>Results:</b> Compared with the non-R/R patients (N = 919), R/R patients (N = 207) had higher all-cause HRU (inpatient, outpatient and emergency room visits; rate ratios [95% <i>CIs</i>]: 1.51 [1.38, 1.65]-1.92 [1.57, 2.37]; all P < 0.001) and healthcare costs ($81,645 vs. $34,717; cost difference [95% CI] = $50,170 [$40,555, $61,383]; P < 0.001).<b>Conclusion:</b> CLL/SLL patients who are R/R to ibrutinib bear a substantial economic burden.