Health Care Resource Utilization and Costs Among Patients with Acute Lymphoblastic Leukemia Receiving Inotuzumab Ozogamicin and Blinatumomab during First Salvage in Relapse/Refractory

Inotuzumab ozogamicin (InO) and blinatumomab (blina) have improved survival for relapsed/refractory (R/R) acute lymphoblastic leukemia (ALL). Studies of health care resource utilization (HCRU) and associated costs for these agents during R/R in the real-world health care delivery context is limited. We examined all-cause and ALL-related HRCU and costs among patients receiving InO or blina during first salvage in R/R using claims data from a large national US health insurer.

Methods

This observational retrospective study comprised commercial and Medicare Advantage enrollees age ≥ 18 years with ALL from 1 January 2015 to 28 February 2021; in R/R first salvage, 29 and 23 patients received InO and blina, respectively. ALL definition was ≥ 2 non-diagnostic claims, on separate days, with International Classification of Diseases (ICD)-9-Clinical Modification (CM) codes=204.0X or ICD-10-CM=C91.0X. "All-cause” was utilization and costs for any condition treated and "ALL-related” was for ALL treatment, both during the first salvage R/R. Transplants were not included in utilization and costs. Inverse probability of treatment weights, to standardize comparisons between InO and blina by baseline socio-demographic and clinical characteristics, were applied in all analyses. All HRCU and cost measures are reported as mean per-patient-per-month (PPPM) because of variable follow-up time. Costs are in 2020 US dollars. Differences were significant at alpha=0.05.

Results

At baseline, InO patients were slightly older than blina patients (mean=54 and 49 years), 50% of InO and 56% of blina patients were female, and 34% of InO patients had ≥ 3 comorbidities compared with 20% of blina. Mean (median) continuous follow-up (days) for InO=528 (445) and blina=588 (456). The most frequent HRCU for both patient groups was hospital outpatient visits; for both groups, all-cause hospital outpatient visits were more frequent than ALL-related (all-cause: InO=11.2; blina=10.5 and ALL-related: InO=8.5; blina=9.0) (Table 1). None of the differences in HRCU and costs reported in text are statistically significant, likely because of the study's small sample size. Office visits were the second highest HRCU where InO patients had lower all-cause visits but higher ALL-related visits (all-cause: InO=3.5; blina=3.1 and ALL-related: InO=3.7; blina=3.2). For inpatient stays, InO and blina patients had similar all-cause and ALL-related mean stays (range=0.8 to 1.0). However, among those with inpatient stays, length of stay for blina patients was nearly twice as many days as for InO patients (All-cause: InO=7.2; blina=14.1; ALL-related: InO=7.6; blina=14.1). InO patients had more all-cause and ALL-related ICU stays than blina patients (all-cause: InO=0.6; blina=0.3 and ALL-related: InO=0.2; blina=0.1.).

Both all-cause and ALL-related total healthcare costs, respectively, were 44% and 47% higher for blina patients than those receiving InO (Table 2). The higher medical costs among blina patients were largely driven by higher inpatient stay costs; all-cause and ALL-related inpatient stay costs were approximately three times higher for blina patients compared with InO (all-cause: InO=$34,375; blina=$110,364; ALL-related: InO=$37,636; blino=$110,364). InO patients had higher all-cause and ALL-related office and outpatient hospital visits costs; the biggest difference was ALL-related office visits (InO=$11,646 and blina=$2,898). Whereas costs of all-cause ICU stays were similar for InO and blina patients, ALL-related ICU costs were higher among InO patients compared with blina ($25,176 and $5,479), which may be related to initial admission upon relapse.

Conclusions

During R/R first salvage, patients receiving InO had considerably lower all-cause and ALL-related total medical costs than those receiving blina. While both all-cause and ALL-related ambulatory care costs were higher among patients receiving InO, the considerably higher costs of inpatient stays among patients receiving blina eclipsed the cost of outpatient care among patients receiving InO. These study results suggest that those receiving InO in first salvage in R/R could have lower healthcare costs than those receiving blina. Although numerically large, differences were not significant, likely due to small sample sizes, despite using data from one of the largest US health insurers. Additional studies are welcome to confirm these findings.

Russell-Smith:Pfizer: Current Employment, Current holder of stock options in a privately-held company. Murphy:Pfizer: Consultancy. Nguyen:Pfizer: Consultancy. Cao:Pfizer: Consultancy. Li:Pfizer: Consultancy. Shah:Pfizer: Current Employment, Current holder of stock options in a privately-held company.