Ondansetron versus palonosetron as a marker of non-adherence to antiemetic prophylaxis guidelines in highly emetogenic chemotherapy.

Abstract

e23108 Background: ASCO antiemetic guidelines recommend upfront triple prophylaxis (NK1 receptor antagonist (RA) + 5HT3 RA + dexamethasone) for patients receiving highly emetogenic chemotherapy (HEC). Physicians exhibit high variation in HEC guideline adherence, principally involving inclusion of NK1 RA. Whether adherence is associated with selection of the specific 5HT3 RA agent remains inadequately studied. Methods: In the IBM Explorys electronic health record database, we used procedure and diagnosis codes to identify HEC courses and related nausea/vomiting (NV) from 2012 to 2018. We defined HEC guideline adherence as triple prophylaxis at chemotherapy initiation. We assigned HEC courses for ≥ 7 day cycles of cisplatin or anthracycline + cyclophosphamide (AC), or carboplatin (≥ 14 day cycles as a proxy for AUC ≥ 4) to prescribing oncologists based on encounter frequency. We categorized 5HT3 RA use of each physician treating ≥ 5 HEC courses based on their most commonly used 5HT3 and performed descriptive statistics. Results: Of 12,262 HEC courses, 57% involved physicians having greater use of ondansetron (OND) (mean OND to palonosetron (PALO) ratio of 3.9:1). These courses had lower guideline adherence (due to NK1 RA omission) and higher rates of NV for combined HEC, AC, and carboplatin. NV rates for cisplatin did not vary by 5HT3 agent used. Courses involving physicians with greater PALO use (mean OND:PALO ratio of 0.2:1) had superior adherence and NV rates, despite involving a slightly higher risk population (younger and/or female). Conclusions: According to HEC antiemetic guidelines, NK1 RA use should occur independent of 5HT3 RA agent selection. However, we observed less NK1 RA use where OND was preferred, which may have caused the observed higher rates of NV with OND. Further evaluation should assess whether pharmacy cost minimization is a driver of both OND preference and NK1 omission in HEC. [Table: see text]