Impact of pre-existing diabetes mellitus on acute care use in older patients with metastatic prostate cancer on androgen receptor signaling inhibitors.

119 Background: Androgen receptor signaling inhibitors (ARSIs) are mainstay treatments for metastatic prostate cancer. Hyperglycemia is a common side effect but limited data exists on outcomes such as hospitalizations in patients with diabetes mellitus (DM) starting on ARSIs. Methods: We used the SEER-Medicare linked data for patients aged 66 and older with de novo metastatic prostate cancer who were prescribed abiraterone, enzalutamide, or apalutamide per part D files from 2011 to 2019. Eligible patients had continuous Medicare Part A/ B coverage before and after drug initiation, and Part D coverage before initiation. Patients were excluded if they died within 6 months of diagnosis or received chemotherapy prior to ARSI (<1%). Univariate associations between covariates and DM were assessed using chi-square tests or t-tests. Negative binomial regression was used to calculate incidence rate ratios of acute care use (total number of hospital or emergency admissions divided by total time at risk) for each model covariate among DM and non-DM patients after initiation of ARSI. Results: 2697 patients met eligibility criteria, of which 17.4% (469) had DM. The average age of the cohort was 75.0 years ±7.0 SD. 85.3% (2300) of patients received androgen deprivation therapy (ADT) prior to ARSI, and 0.9% (24) received ADT afterwards. 28.3% (773) of patients received abiraterone only, 23.8% (641) received only enzalutamide or apalutamide, and 47.6% (1283) received both treatments. Patients with DM (vs without) differed significantly with regards to lower high school education, higher NCI comorbidity score (excluding DM), and less receipt of abiraterone, but not in age, race, marital status, prior ADT treatment, or receipt of enzalutamide or apalutamide. 29.5% (797) of patients had acute care use within 6 months, with 39.9% (187) in the DM group and 27.4% (610) in the non-DM group ( p <.0001), Adjusted for covariates, patients with DM had a 41% increased rate of acute care use ( p =0.0016) compared to those without DM. Additionally, compared to those prescribed only enzalutamide or apalutamide, patients prescribed abiraterone had a 47% increased rate of acute care use ( p =0.0026); this was independent of having DM (interaction p =0.77). Conclusions: Patients with pre-existing DM on ARSIs experienced higher rates of acute care use compared to those without DM, regardless of ARSI type. Future studies should assess potential interventions in older patients with diabetes on ARSIs, such as close monitoring of glycemic status or adherence to risk reduction medications.