Discussion
To the authors’ knowledge, this study is the first to examine the real-world incidence of bleeding and Afib in veterans who received ibrutinib for CLL in the first year of its availability. The study found minimal use of anticoagulants and/or antiplatelet agents prior to receiving first-line ibrutinib or BR, and very low use of these agents in the first 6 months following the initiation of first-line treatment. This finding suggests a high awareness among VA providers of potential adverse effects (AEs) of ibrutinib and chemotherapy, and a careful selection of patients that lack risk factors for AEs.
In patients treated with first-line ibrutinib when compared with patients treated with first-line BR, moderate increases in bleeding (2.7% vs 8.1%, P = .008) and Afib (10.5% vs 3%, P = .003) also were observed. These results are concordant with previous findings examining the use of ibrutinib in patients with CLL.18-20
Limitations
The results of this study should be interpreted with caution, as some limitations must be considered. The study was conducted in the early days of ibrutinib adoption. Since then, more patients have been treated with ibrutinib and for longer durations. As clinicians gain more familiarity and with ibrutinib, and as additional novel therapeutics emerge, it is possible that the initial awareness about risks for possible AEs may diminish; patients with high comorbidity burdens and concomitant medications would be especially vulnerable in cases of reduced physician vigilance.
Another limitation of this study stems from the potential for dual system use among patients treated in the VHA. Concurrent or alternating use of multiple health care systems (use of VHA and private-sector facilities) may present gaps in the reconstruction of patient histories, resulting in missing data as patients transition between commercial, the Centers for Medicare and Medicaid Services, and VHA care. As a result, the results presented here do not reflect instances where a patient experienced a bleeding event treated outside the VA.
Problems with missing data also may occur due to incomplete extraction from the electronic health record; these issues were addressed by leveraging an understanding of the multiple data marts within the CDW environment to harmonize missing and/or erroneous information through use of other data marts when possible. Lastly, this research represents a population-level study of the VHA, thus all findings are directly relevant to the VHA. The generalizability of the findings outside the VHA would depend on the characteristics of the external population.
Conclusion
Real-world evidence from a nationwide cohort of veteran patients with CLL treated with ibrutinib suggest that, while there is an association of increased bleeding-related events and Afib, the risk is comparable to those reported in previous studies.18-20 These findings suggest that patients in real-world clinical care settings with higher levels of comorbidities may be at a slight increased risk for bleeding events and Afib.