Clinical adjusters in the EOM: A deep dive into HER2.

86 Background: The Enhancing Oncology Model (EOM) incorporates several cancer-specific clinical adjusters to establish cost benchmarks, with breast cancer categorized into four distinct cost groups based on HER2 status and metastatic status. However, these classifications evolve over time as the costs of associated therapies fluctuate. Methods: We partnered with a large community oncology practice, which accounted for nearly 10% of all EOM episodes. We analyzed episode-level performance data, medical claims, and Part D drug events from the first performance period, along with historical episode claims data for initial treatments from January 2019 to December 2021. To determine HER2 status, we identified the presence of HER2-targeted drug claims through outpatient records, carrier claims, and Part D drug events. We then compared the average episode costs of HER2-positive and HER2-negative breast cancer episodes across each six-month period in both historical and performance-period datasets. Results: In historical episode data, the HER2 adjuster accurately reflects cost differences between HER2-positive and HER2-negative episodes. However, in the first performance period, HER2 status appears to overestimate costs for HER2-positive episodes while underestimating costs for HER2-negative episodes. Conclusions: HER2 status appears to be a less reliable predictor of episode spending in the first performance period compared to baseline data, potentially due to the impact of declining cost of trastuzumab products following the introduction of multiple biosimilars in HER2-positive disease, and the increasing cost of newer therapies in HER2-negative disease. Also, this clinical adjuster is applied outside the price prediction model, which is rerun every 6 months to determine the trend factor, and fails to account for evolving treatment patterns and cost trends. Given the ever evolving landscape of oncology treatment, we recommend CMMI revisit clinical adjusters regularly to ensure appropriate adjustments based on current standards of care. Data type Period Average episode cost for HER2 positive episodes Average episode cost for non-HER2 positive episodes Ratio Historical data h1-2019 $60,591 $43,248 1.40 Historical data h2-2019 $57,783 $47,147 1.23 Historical data h1-2020 $56,644 $43,711 1.30 Historical data h2-2020 $62,485 $40,019 1.56 Historical data h1-2021 $55,425 $38,493 1.44 Historical data h2-2021 $50,932 $37,757 1.35 Performance period 1 h2-2023 $46,882 $46,290 1.01