The utility value of ROX index and modified ROX index in determining the efficiency of HFNC in children admitted with respiratory distress

Abstract

Background: The ROX index is defined as the ratio of SpO2/FiO2 to respiratory rate. The modified ROX index or ROX-HR index is defined as the ratio of ROX index/heart rate×100. The aim of the study was to determine the utility of the ROX index and the modified ROX index as predictors of initiation and efficiency of HFNC in children admitted with respiratory distress. Methods: This prospective observational study included 133 children with respiratory distress, who received HFNC. The ROX index, and modified ROX index were measured, and outcomes were recorded. Results: Total number of study subjects were 133. Statistically significant increase was seen in ROX index and modified ROX index at follow up (p value<0.05). Interpretation of the area under the ROC curve showed that the performance of ROX index and modified ROX index at ‘0’ hour was outstanding. ROX Index and modified ROX Index at a Cut-off of ≤4.7959 and ≤2.5579 respectively at initiation i. e.; at ‘0’ hour predicted HFNC requirement. In prediction of HFNC requirement ROX index at ‘0’ hour had a sensitivity, specificity, positive predictive value, and negative predictive value of 88.24%, 87.84%, 93%, and 80.2% respectively, and modified ROX index had 78.68%, 93.24%, 95.5%, and 70.4% respectively. Low ROX and modified ROX indices at ‘0’ hour predicted prolonged ICU and hospital stays, as well as extended HFNC duration. Conclusions: Both ROX index, and modified ROX index were good predictors of HFNC requirement.