Healthcare resource utilization and costs of Medicare-enrolled patients with HR+/HER2- metastatic breast cancer treated with CDK4/6i in the first-line setting

Abstract

Abstract Healthcare resource utilization and costs of Medicare-enrolled patients with HR+/HER2- metastatic breast cancer treated with CDK4/6i in the first-line setting Emma Behan Chair of Supervisory Committee: Aasthaa Bansal, PhD Background: The introduction of cyclin-dependent kinases 4 and 6 (CDK4/6i) inhibitors (palbociclib, ribociclib, and abemaciclib) has transformed the treatment landscape for patients with hormone-receptor-positive (HR+) and human epidermal growth factor receptor 2 negative (HER2-) metastatic breast cancer (MBC). To our knowledge, no studies have quantified healthcare resource utilization (HRU) or economic burden following CDK4/6i initiation in the Medicare population. Objective: The objective of this study is to describe HRU and quantify healthcare costs among Medicare-enrolled patients with HR+ HER2- MBC treated with CDK4/6i in the first-line setting.Methods: We conducted a retrospective cohort study on Medicare-enrolled HR+ HER2- MBC patients who initiated a CDK4/6i in the first-line setting between February 2nd, 2016, and December 31st, 2022 using claims from the Merative MarketScan ® database. We examined all-cause healthcare resource utilization (HRU) by summarizing the number of inpatient (IP), outpatient (OP), and emergency room (ER) visits, as well as the length of stay during the six months following CDK4/6i initiation. Additionally, we assessed all-cause healthcare costs, including IP, OP, ER, and pharmacy, over the one year following CDK4/6i initiation using the Kaplan-Meier sample average (KMSA) estimator to account for censoring. We reported total healthcare costs as the sum of IP, OP, ER, and pharmacy costs, providing insights into the economic burden associated with CDK4/6i treatment in this patient population. Results: A total of 901 patients met the inclusion criteria with a mean age of 74 years (standard deviation [SD] 6.84) and a mean Charlson Comorbidity Index (CCI) score of 0.64 (SD 0.8). Most patients initiated palbociclib (n=804 (90%)) at the index date and most had a systemic therapy (n=634 (70%)) before CDK4/6i initiation. Nearly 24% (n=214) had an inpatient admission in the six months following CDK4/6i initiation. Among patients with an inpatient admission, the mean number of admissions per patient was 1.65 (SD=0.98) with a mean length of stay per admission of 5.98 days (SD=6.25). Roughly 30% [n=271] of patients had an ER visit, with a mean of 2.1 (SD=1.54) visits per patient among those who had a visit. Most patients (n=868 (96.44%)) had an outpatient service, and among those with an OP service, the mean number of days with outpatient services was 19.96 (SD=12.29). Mean total healthcare costs over the one-year period following CDK4/6i were $62,228 (95% CI 52281, 73029) per patient with the main drivers being outpatient services ($31,686 (95% CI 27168, 36925)) and pharmacy costs ($22,727 (95% CI 19273, 25931)).