A risk stratification model for high-flow nasal cannula use in patients with coronavirus disease 2019 in Japan: a single-center retrospective observational cohort study

Abstract BackgroundThe coronavirus disease 2019 (COVID-19) pandemic has put a strain on the healthcare system, and sudden changes in disease status during home treatment have become a serious issue. Therefore, prediction of disease severity and allocation of sufficient medical resources, including high-flow nasal cannula (HFNC), to patients in need are important. We aimed to determine risk factors for the need of HFNC use in COVID-19. MethodsThis was a single-center retrospective observational cohort study including all eligible hospitalized adult patients aged ≥18 years diagnosed with COVID-19 between April 14, 2020 and August 5, 2021 who were treated in the study hospital. The primary outcome was critical respiratory illness meeting one of the following criteria: oxygenation flow rate ≥ 10 L/min, high-flow oxygenation, noninvasive ventilation, invasive ventilation, and death. Nineteen potential predictive variables, including patient characteristics at hospital admission, were screened using least absolute shrinkage and selection operator and logistic regression to construct a predictive risk score. Accuracy of the risk score was determined using area under the receiver operating characteristic curve. ResultsThe study cohort included 148 patients. The rate of critical respiratory illness was 22.9% (all patients needed high-flow device support). Among the 19 potential variables, percutaneous oxygen saturation (SpO2) <92% (odds ratio [OR] 7.50, 95% confidence interval [CI] 2.806–20.82) and IL-6 (OR 1.021, 95% CI 1.010–1.033) were included in developing the risk score, which was termed interleukin (IL)-6-based COVID-19 severity (IBC-S) score. ConclusionsThe IBC-S score, an easy-to-use risk score based on parameters available at the time of hospital admission, predicted critical respiratory failure in patients with COVID-19. In primary care settings, the IBC-S score based on interleukin-6 and SpO2 might aid in determining patients who should be transported to a tertiary medical institution or an isolation facility.