8 Background: The overuse of neurokinin-1 receptor antagonists (NK1-RAs) is a focus of quality measurement within the American Society of Clinical Oncology Quality Oncology Practice Initiative (ASCO-QOPI) and the American Board of Internal Medicine (ABIM) as a Choosing Wisely measure. The Michigan Oncology Quality Collaborative (MOQC) is a statewide collaborative with participation of nearly 100% of oncologists. The purpose of this project was to provide quality improvement practice support for deimplementation of NK1-RAs in the upfront prevention of chemotherapy- induced nausea and vomiting (CINV) for low and moderate emetic chemotherapy regimens (QOPI measure SMT28a) to less than 30% in practices across the State, with lower scores indicating better performance. Methods: In 2018, MOQC added the QOPI SMT28a measure as part of its standard quality measure module for collection by all MOQC practices. A quality improvement intervention was initiated that consisted of 1) baseline assessments of measure performance, prescriber knowledge and beliefs, and pre-populated antiemetic order sets, 2) reporting practice and state-level performance to MOQC practices, 3) state-wide CINV education, and 4) a value-based reimbursement (VBR) related to measure performance. Post-intervention performance was assessed with the Fall 2019 and Spring 2020 QOPI-measurement. Results: Responses from a survey assessing pre-populated antiemetic order sets (32/43, 74% response rate), 23% of practices had a pre-populated order set for NK1-RA and/or olanzapine in moderate emetic regimens. The post-education order set survey found that 48% of respondents (25/43, 54% response rate) either modified or were in the process of modifying their order sets. Conclusions: Deimplementation of unnecessary and low value antiemetics in patients receiving low- or moderate emetic chemotherapy was possible via a state-wide quality improvement program that involved performance reporting to practices, collaborative-wide education, modification of standing order sets, and VBR based on performance. [Table: see text]