Attributes and Health Care Resource Utilization of Patients on Enzalutamide or Abiraterone for Metastatic Castration-Resistant Cancer in England.

[PURPOSE] To compare demographics, clinical characteristics, health care resource utilization (HCRU), treatment duration, and overall survival (OS) with enzalutamide (ENZA) or abiraterone acetate (AA) in patients with metastatic castration-resistant prostate cancer (mCRPC) in England.

[MATERIALS AND METHODS] This retrospective study analyzed data from the Cancer Analysis System database on patients receiving ENZA or AA (January 2014-March 2020) for chemotherapy-naïve mCRPC (mCRPC was the only funded indication for ENZA/AA during study period). Baseline characteristics were assessed using standardized mean difference (SMD) (<0.1: balanced); differences were adjusted for using propensity score weighting (PSW). Cox proportional hazard models were used for OS and treatment duration. Number needed to treat was calculated from HCRU incidence rate ratios (IRRs).

[RESULTS] Overall, 8,485 patients were included (ENZA, 5,330; AA, 3,155). Diabetes mellitus was more prevalent in the ENZA group (SMD, 0.12) at treatment initiation. HCRU was comparable between groups before treatment initiation (SMD < 0.1), but HCRU IRR after treatment initiation favored ENZA. Compared with AA, ENZA was associated with significantly fewer inpatient stays, outpatient or accident and emergency (A&E) visits, and hospitalization days ( < .01), and significantly lower likelihood of treatment discontinuation (adjusted hazard ratio [aHR], 0.90 [95% CI, 0.86 to 0.96]; < .01) and mortality risk (aHR, 0.92 [95% CI, 0.87 to 0.98]; = .010). Assuming 8 months' treatment and comparable groups through PSW, 1.9 inpatient admissions, 17.3 outpatient visits, 1.4 A&E visits, and 19.5 hospitalization days could be avoided per 10 patients on ENZA versus AA.

[CONCLUSION] Patients with mCRPC on ENZA or AA had generally similar baseline characteristics apart from diabetes prevalence. ENZA was associated with longer OS and treatment duration, and lower HCRU after treatment initiation than AA.