AUTHOR=Xu Jiqian , Yang Xiaobo , Huang Chaolin , Zou Xiaojing , Zhou Ting , Pan Shangwen , Yang Luyu , Wu Yongran , Ouyang Yaqi , Wang Yaxin , Xu Dan , Zhao Xin , Shu Huaqing , Jiang Yongxiang , Xiong Wei , Ren Lehao , Liu Hong , Yuan Yin , Qi Hong , Fu Shouzhi , Chen Dechang , Zhang Dingyu , Yuan Shiying , Shang You 

TITLE=A Novel Risk-Stratification Models of the High-Flow Nasal Cannula Therapy in COVID-19 Patients With Hypoxemic Respiratory Failure

JOURNAL=Frontiers in Medicine

VOLUME=7

YEAR=2020

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2020.607821

DOI=10.3389/fmed.2020.607821

ISSN=2296-858X

ABSTRACT=<p><bold>Background:</bold> High-flow nasal cannula (HFNC) has been recommended as a suitable choice for the management of coronavirus disease 2019 (COVID-19) patients with acute hypoxemic respiratory failure before mechanical ventilation (MV); however, delaying MV with HFNC therapy is still a dilemma between the technique and clinical management during the ongoing pandemic.</p><p><bold>Methods:</bold> Retrospective analysis of COVID-19 patients treated with HFNC therapy from four hospitals of Wuhan, China. Demographic information and clinical variables before, at, and shortly after HFNC initiation were collected and analyzed. A risk-stratification model of HFNC failure (the need for MV) was developed with the 324 patients of Jin Yin-tan Hospital and validated its accuracy with 69 patients of other hospitals.</p><p><bold>Results:</bold> Among the training cohort, the median duration of HFNC therapy was 6 (range, 3–11), and 147 experienced HFNC failure within 7 days of HFNC initiation. Early predictors of HFNC failure on the basis of a multivariate regression analysis included age older than 60 years [odds ratio (OR), 1.93; 95% confidence interval (CI), 1.08–3.44; <italic>p</italic> = 0.027; 2 points], respiratory rate-oxygenation index (ROX) &lt;5.31 (OR, 5.22; 95% CI, 2.96–9.20; <italic>p</italic> &lt; 0.001; 5 points) within the first 4 h of HFNC initiation, platelets &lt; 125 × 10<sup>9</sup>/L (OR, 3.04; 95% CI, 1.46–6.35; <italic>p</italic> = 0.003; 3 points), and interleukin 6 (IL-6) &gt;7.0 pg/mL (OR, 3.34; 95% CI, 1.79–6.23; <italic>p</italic> &lt; 0.001; 3 points) at HFNC initiation. A weighted risk-stratification model of these predictors showed sensitivity of 80.3%, specificity of 71.2% and a better predictive ability than ROX index alone [area under the curve (AUC) = 0.807 vs. 0.779, <italic>p</italic> &lt; 0.001]. Six points were used as a cutoff value for the risk of HFNC failure stratification. The HFNC success probability of patients in low-risk group (84.2%) was 9.84 times that in the high-risk group (34.8%). In the subsequent validation cohort, the AUC of the model was 0.815 (0.71–0.92).</p><p><bold>Conclusions:</bold> Aged patients with lower ROX index, thrombocytopenia, and elevated IL-6 values are at increased risk of HFNC failure. The risk-stratification models accurately predicted the HFNC failure and early stratified COVID-19 patients with HFNC therapy into relevant risk categories.</p>