Hospitalizations in veterans treated with monotherapy vs combination therapy for metastatic hormone sensitive prostate cancer.

72 Background: Current treatment of metastatic hormone sensitive prostate cancer (mHSPC) includes androgen deprivation therapy (ADT) monotherapy or combination therapy (ADT + docetaxel or an androgen receptor pathway inhibitor). However, no comparative studies have been conducted to assess the hospitalization rates and causes of admission between the two treatment groups. We assessed the hospitalization rates of the different therapies to determine adverse events and improve treatment selection in mHSPC. Methods: A nationwide retrospective study of 6,651 US Veterans with de novo mHSPC in the Veterans Health Administration between 2013-2021. Baseline characteristics for each treatment group were obtained including age, prostate serum antigen (PSA), total number of cardiac drugs, and total number of Anatomic Therapeutic Chemical (ATC) drugs. The five most frequent ICD codes associated with hospitalizations were obtained for each group, excluding the ICD codes for prostate cancer and bone metastases. Quasi-Poisson regression was used to determine differences in hospitalization rates between the two groups. Results: Evaluation of the median baseline characteristics between the two groups showed increased age and decreased PSA (Table). There was no difference between the number of cardiac drugs and total number of ATC drugs between the groups. The 5 most frequent ICD codes for monotherapy were AKI (17%), UTI (11%), essential hypertension (7%), sepsis (5%), and acute post-hemorrhagic anemia (4%). The 5 most frequent ICD codes for combination therapy were AKI (17%), UTI (13%), acute hypoxic respiratory failure (8%), sepsis (7%), and malnutrition (6%). The monotherapy group had a greater increase in hospitalization rates after therapy initiation when compared to combination therapy ( see table ). Quasi-Poisson regression for the hospitalization rates between the two groups had a p-value of 0.018. Conclusions: The rate of hospitalizations increased in the monotherapy treatment group compared to combination therapy. This is likely due to the monotherapy treatment group having a more advanced age and more severe comorbidities. Future directions could include comparing hospitalization rates of combination therapy with ARPI vs docetaxel. This analysis will guide physicians in selecting the more appropriate therapy according to a patient’s individual risk profile and co-morbidities. Age (p < 0.001) PSA(p = 0.008) Pre-treatment hospitalization rate Post-treatment hospitalization rate ADT monotherapy(n = 5146) 75.0 76.2 120 per 1000 person-years 340 per 1000 person-years ADT combination therapy (n = 1505) 72.0 86.3 100 per 1000 person-years 260 per 1000 person-years