The association between Vital Signs at Hospital Admission and Adverse Outcomes in Patients with COVID-19: A Retrospective Cohort Study.

Niklas Lidströmer^1,2,3Marat Murzabekov^1,2,3Niklas Borg^1,2,3Michael Runold⁴Eric Herlenius^1,2,3*Susanne Rautiainen^2,3,4,5

• ¹Department of Women's and Children's Health, CMM, Karolinska Institutet (KI), Solna, Stockholm, Sweden
• ²Astrid Lindgren Children’s Hospital, Karolinska University Hospital, Stockholm, Stockholm, Sweden
• ³Center for Molecular Medicine, Karolinska University Hospital, Stockholm, Stockholm, Sweden
• ⁴Department of Medicine, Karolinska Institutet (KI), Solna, Stockholm, Sweden
• ⁵Clinical Epidemiology Division, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden

Background: Vital sign measurements at hospital admission are used to identify patients at risk for adverse events. However, how vital signs at admission are related to adverse outcomes among COVID-19 patients is not fully characterized.Objectives: To characterize vital signs at admission and their associations with intensive care unit/intermediate care unit (ICU/IMCU) admission and in-hospital mortality in adult patients with COVID-19.Methods: This retrospective cohort study included 2,826 adults admitted with COVID-19 to Karolinska University Hospitals, Stockholm, Sweden, between 2 March 2020 and 1 June 2021. The Cox proportional hazards model was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between vital signs at admission and ICU/IMCU admission and in-hospital mortality.Results: The median age was 62.2 years, and 62.1% were men. Each unit increase in respiratory rate (HR 1.03, 95% CI 1.02–1.05), heart rate (HR 1.01, 95% CI 1.00–1.02), temperature (HR 1.21, 95% CI 1.11–1.32), and each unit decrease in saturation (HR 1.05, 95% CI 1.04–1.06) were associated with ICU/IMCU admission. Respiratory rate (HR 1.04, 95% CI 1.02–1.07) and saturation (HR 1.04, 95% CI 1.02–1.06) were also associated with in-hospital mortality. These associations persisted across pandemic waves and subgroups of age, gender, medication use, and oxygen support.Conclusion: Respiratory rate and lower saturation at admission were associated with increased ICU/IMCU admission and in-hospital mortality. Our findings suggest that greater emphasis on respiratory rate and oxygen saturation in early warning scores - such as the revised Sequential Organ Failure Assessment (SOFA) score and other sepsis prediction models, to improve risk stratification of viral sepsis, especially in patients with COVID-19.