Postpandemic Recovery of Case Mix Index and Risk-Adjusted Mortality in US Hospitals

In this cohort study of 715 US hospitals from 2019 to 2024, risk-adjusted in-hospital mortality declined significantly following the COVID-19 pandemic, resuming its prepandemic trajectory of improvement, while patient acuity as measured by CMI remained elevated. These findings suggest a new postpandemic baseline for patient acuity, whereas hospital mortality outcomes have returned to prior improvement trends.