BACKGROUND: Breast cancer is the most common cancer in women, accounting for considerable health care expenditure.
OBJECTIVE: To evaluate economic outcomes in patients with hormone receptor positive/human epidermal growth factor receptor 2–negative metastatic breast cancer treated with first- or second-line cyclin-dependent kinase 4/6 in-hibitors (CDK4/6i): palbociclib (palbo), abemaciclib (abema) or ribociclib (ribo). Other similar studies in this population had short follow-up, with many patients receiving CDK4/6is off-label.
METHODS: A retrospective analysis was conducted on 3,617 patients (aged ≥18 years) using Optum’s Clinformatics Dat-aMart dataset from January 1, 2014, to September 30, 2021. Patients were included if they had at least 1 pharmacy claim for palbo, abeam, or ribo in first- or second-line and had at least 6 months of continuous health plan enrollment in the pre-index (date of first CDK4/6i claim) and follow-up periods. All-cause per patient per month (PPPM) medical (in-patient, emergency department, and outpatient) health care resource use (HCRU) and costs, and outpatient pharmacy prescriptions costs, were compared between CDK4/6is by adjusting for differences in patients’ baseline characteristics using inverse probability of treatment weighting. Subgroup analyses evaluated Medicare patients aged 65 years or older.
RESULTS: We identified 3,182 palbo, 286 abema, and 149 ribo patients with a median follow-up of 20.8, 16.6, and 19.9 months, respectively. Median age ranged between 69 and 71 years. After inverse probability of treatment weighting adjustment, palbo was associated with a lower risk of inpa-tient admissions (35.8% vs 41.6%; odds ratio = 1.31; P = 0.034) vs abema. No other differences were seen for HCRU. Com-pared with abema, PPPM outpatient costs were lower with palbo by $754 (P = 0.05). PPPM inpatient ($2,252 vs $6,286), medical ($6,948 vs $11,717), and total ($19,370 vs $23,639) costs were lower with palbo vs abema, although not statisti-cally significant. PPPM HCRU were not different with palbo vs ribo, whereas PPPM inpatient ($2,252 vs $4,362), medical ($6,948 vs $8407), and total ($19,370 vs $20,951) costs were lower with palbo, but not statistically significant. In Medi-care patients, PPPM medical costs were lower with palbo vs abema by $1,608 [P = 0.04], whereas other costs were not different. No differences in costs were seen with palbo vs ribo.
CONCLUSIONS: All-cause HCRU and costs were generally similar between the CDK4/6is but trended in favor of palbo for inpatient and medical costs vs abema. Alongside effica-cy and safety, HCRU and costs should be considered when selecting CDK4/6is to understand the economic impact of treatment.
