What is ROX Index ?

ROX Index

• ROX index was first described by Roca et al to predict HFNC failure in ICU patients suffering from pneumonia.It is defined as a combination of ratio of oxygen saturation to the fraction of inspired oxygen (SpO2/FiO2) and respiratory rate.

• Roca et al study was done on 157 patients were included, of whom 44 (28.0%) eventually required MV (HFNC failure). After 12 hours of HFNC treatment, the ROX index demonstrated the best prediction accuracy (area under the receiver operating characteristic curve 0.74 [95% confidence interval, 0.64-0.84]; P < .002). The best cutoff point for the ROX index was estimated to be 4.88. In the Cox proportional hazards model, a ROX index greater than or equal to 4.88 measured after 12 hours of HFNC was significantly associated with a lower risk for MV (hazard ratio, 0.273 [95% confidence interval, 0.121-0.618]; P = .002), even after adjusting for potential confounding.

• Similarly meta analysis by Prakash et al has demonstrated that ROX index has good discriminating power for prediction of HFNC failure in COVID-19 patients with AHRF. 

Reference

• Prakash J, Bhattacharya PK, Yadav AK et al (2021) ROX index as a good predictor of high fow nasal cannula failure in COVID-19 patients with acute hypoxemic respiratory failure: A systematic review and metaanalysis. J Crit Care 66:102–108.https://doi.org/10.1016/j.jcrc.2021.08.012
• O. Roca, J. Messika, B. Caralt, et al.Predicting success of high-flow nasal cannula in pneumonia patients with hypoxemic respiratory failure: the utility of the ROX index J Crit Care, 35 (2016), pp. 200-205, 10.1016/j.jcrc.2016.05.022