Adverse event rates and economic burden associated with purine nucleoside analogs in patients with hairy cell leukemia: a US population-retrospective claims analysis

Abstract

Background: Purine nucleoside analogs (PNAs) are the recommended first-line treatment for patients with hairy cell leukemia (HCL), but they are associated with adverse events (AEs). Due to a lack of real-world evidence regarding AEs that are associated with PNAs, we used commercial data to assess AE rates, AE-related health care resource utilization (HCRU), and costs among PNA-treated patients with HCL. Adults aged ≥18 years with ≥2 claims for HCL ≥30 days apart from 1 January 2006 through 31 December 2015 were included. Included patients had ≥1 claim for HCL therapy (cladribine ± rituximab or pentostatin ± rituximab [index date: first claim date]) and continuous enrollment for a ≥ 6-month baseline and ≥ 12-month follow-up period. Patient sub-cohorts were based on the occurrence of myelosuppression and opportunistic infections (OIs). Generalized linear models were used to compare HCRU and costs.

Results: In total, 647 PNA-treated patients were identified (mean age: 57.1 years). Myelosuppression and OI incidence were 461 and 42 per 1000 patient-years, respectively. Adjusted results indicated that those with myelosuppression had higher rates of hospitalization (47.4% vs 12.4%; P < .0001) and incurred higher mean inpatient costs ($23,517 vs $12,729; P = .011) and total costs ($57,325 vs $34,733; P = .001) as compared with those without myelosuppression. Similarly, patients with OIs had higher rates of hospitalization (53.8% vs 30.8%; P = .025) and incurred higher mean inpatient costs ($21,494 vs $11,229; P < .0001) as compared with those without OIs.

Conclusions: PNA therapy is highly effective but associated with significant toxicities that increase costs; these findings indicate a need for therapies with improved toxicity profiles and better risk stratification of patients at risk of developing myelosuppression and OIs.

Keywords: Adverse events; Hairy cell leukemia; Myelosuppression; Purine nucleoside analogs.

Fig. 1

Patient selection criteria. ^*OI was defined by any of the following conditions: pulmonary tuberculosis, atypical mycobacteria, cryptococcosis, aspergillosis, histoplasmosis, listeriosis, leishmaniasis, Pneumocystis jiroveci pneumonia, keratitis, onychomycosis, peritonitis, fungemia, endophthalmitis, septic/pyogenic arthritis, and osteomyelitis. HCL hairy cell leukemia, OI opportunistic infection

Fig. 2

Incidence and prevalence of AEs over the 12-month follow-up period among PNA-treated patients with HCL. AEs were identified at any position (primary, secondary) on the claim. AE adverse event, HCL hairy cell leukemia, PNA purine nucleoside analog

Fig. 3

All-cause HCRU during the 12-month follow-up period. ER emergency department/room, ICU intensive care unit, OI opportunistic infection. *Significant at P < .05

Fig. 4

All-cause costs during the 12-month follow-up period. *Significant at P < .05