A Simple Nomogram for Predicting Failure of Non-Invasive Respiratory Therapies in Adults with COVID-19: A Retrospective Multicenter Study

Abstract

Background: Non-invasive respiratory therapies (NIRTs) (high flow nasal cannula and non-invasive ventilation) are widely used in COVID-19 patients who developed acute respiratory failure. However, use of these therapies may delay initiation of invasive mechanical ventilation in some patients and hence worsen their outcome. This study set out to identify early predictors of NIRT failure and to develop a simple-to-use nomogram and an online calculator identifying patients at high risk of NIRT failure. Methods: A retrospective cohort of 652 COVID-19 patients with ARF who received NIRTs, was used to develop early predictors of NIRT failure, defined as subsequent need for invasive mechanical ventilation or death within 28 days after ICU admission. Multivariate logistic analysis was used to develop the nomogram and ten-fold cross-validation was applied to internally validate the stability of the model. Findings: The failure rate of NITRs was 63% (415/652). The ROX index (ratio of pulse oximetry oxygen saturation/fraction of inspired oxygen to respiratory rate), age, GCS score, and use of vasoprEssors on the first day of NIRTs were independent risk factors for NIRT failure (RAGE factors). Based on the multivariate analysis, the RAGE nomogram for NIRTs failure had a C-statistics of 0 . 83 (95% CI:0 . 80–0 . 87). An internal validation demonstrated that the mean C-statistic remained stable (C-statistics=0 . 84±0 . 03). Internal calibration was excellent (calibration slope=1). Interpretation: The nomogram and online calculator are relatively simple-to-use and able to predict the risk of NIRT failure in COVID-19 patients with acute respiratory failure. Funding Statement: This work was supported by Key Research and Development Plan of Jiangsu Province (BE2018743 and BE2019749) and Chinese Academy of Medical Sciences (CAMS) Innovation Fund for Medical Sciences (CIFMS) from Chinese Academy of Medical Sciences (2016-I2M-1-014).Declaration of Interests: All authors have completed the Unified Competing Interest form (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years, no other relationships or activities that could appear to have influenced the submitted work.Ethics Approval Statement: The study was approved by the ethics committee of Jin Yintan Hospital (KY-2020-10.02). Informed consent was waived due to the retrospective and observational nature of the study.