A Prognostic Tool for COVID-19 Decision Support: The Intermountain Risk Score Predicts Major Adverse Health Events in Patients Positive for COVID-19

Background: As the COVID-19 pandemic evolves, stratifying risk is increasingly important. The Intermountain Risk Score (IMRS) uses the complete blood count (CBC) and basic metabolic profile (BMP) as a first-line predictor of mortality and is widely validated. We hypothesized that IMRS predicts COVID-19 outcomes. Methods: Intermountain Healthcare patients aged ≥18 years were evaluated if they had CBC and BMP measured in 2019 and tested positive for COVID-19 in 2020. Viral RNA testing for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was conducted March 3 through November 2, 2020. IMRS used published sex-specific weightings and associations were evaluated for the composite of COVID-19 hospitalization or mortality. Findings: Among 3,883 patients, 8.2% were hospitalized, 1.6% died. Subjects with low, mild, moderate, and high-risk IMRS had the composite endpoint in 3.5% (52/1,502), 8.6% (108/1,256), 15.5% (152/979), and 28.1% (41/146), respectively. Versus low-risk, subjects in mild, moderate, and high-risk groups had HR=2.33 (95% CI: 1.67, 3.24), HR=4.01 (CI: 2.93, 5.50), and HR=8.34 (CI: 5.54, 12.57), respectively. Subjects aged