Validity of the ROX index in predicting invasive mechanical ventilation requirement in pneumonia.

BACKGROUND: The ROX index (Respiratory rate-OXygenation) has been described as a prediction tool to identify the need for invasive mechanical ventilation (IMV) in community-acquired pneumonia (CAP) with acute hypoxaemic respiratory failure treated with high-flow nasal cannula in order to avoid delay of a necessary intubation. However, its use in predicting the need for ventilatory support in hospitalised patients with CAP has not been validated. METHODS: This is a retrospective cohort study including subjects with CAP treated in the general ward, emergency service or intensive care unit of a third-level centre in Cundinamarca, Colombia, between January 2001 and February 2020. The ROX index was estimated as the ratio of oxygen saturation/fraction of inspired oxygen to respiratory rate. RESULTS: A total of 895 patients were included, of whom 93 (10%) required IMV. The ROX index proved to be a good predictor, presenting an area under the curve of receiver operating characteristics (AUROC) of 0.733 (95% CI 0.671 to 0.795, p<0.001) when determined by pulse oximetry and an AUROC of 0.779 (95% CI 0.699 to 0.859, p<0.001) when estimated by arterial blood gas (ABG) parameters, with an intraclass correlation of 0.894. The estimated cut-off point was 14.8; a score less than 14.8 indicates high risk of requiring IMV. CONCLUSION: The ROX index is a good predictor of IMV in hospitalised patients with CAP. It presents good performance when calculated through pulse oximetry and can replace the one calculated by ABG.

Performance of the CORB (Confusion, Oxygenation, Respiratory Rate, and Blood Pressure) Scale for the Prediction of Clinical Outcomes in Pneumonia.

Background: Community-acquired pneumonia (CAP) is a common cause of morbidity and mortality due to misdiagnosis and inappropriate treatment approaches. Objective: To assess the performance of the CORB score in subjects with CAP for predicting in-hospital mortality, death within 30 days of admission, and requirement for invasive mechanical ventilation (IMV) and vasopressor support. Methods: A retrospective, cohort study with diagnostic test analysis of CORB and CURB-65 scores in subjects with CAP according to ATS criteria was undertaken. An alternative CORB score was estimated by replacing SpO2 ≤90% by the SpO2/FiO2 ratio. Crude and adjusted odd ratios (AOR) were calculated for each variable. The area under the receiver operating characteristics curve (AUROC) was constructed for each score, and outcomes were analyzed. AUROCs were compared with the DeLong test, considering a p value <0,05 statistically significant. Results: From 1,811 subjects who entered the analysis, 15.1% (273/1,811) died in hospital, 8.78% required IMV (159/1,811), and 9.77% (177/1,811) needed vasopressor support. CORB had an AUROC of 0,660 (95% CI: 0,623-0,697) for in-hospital mortality; an AUROC of 0,657 (95% CI: 0,621-0,692) for 30-day mortality; an AUROC of 0,637 (CI 95%: 0,589-0,685) for IMV requirement; and an AUROC of 0,635 (95% CI: 0,589-0,681) for vasopressor support. CORB performance increases when the SpO2/FiO2 ratio <300 is used as oxygenation criterion in the prediction of requirement for IMV and vasopressor support, with AUROC of 0,700 (95% CI: 0,654-0,746; p < 0.001) and AUROC of 0,702 (95% CI: 0,66-0,745; p < 0.001), respectively. CURB-65 score presents an in-hospital mortality AUROC of 0,727 (95% CI: 0,695-0,759) and 30-day mortality AUROC of 0,726 (95% CI: 0,695-0,756). Conclusions: CORB score has a good performance in predicting the need for IMV and vasopressor support in CAP patients. This performance improves when the SpO2/FiO2 ratio <300 is used instead of the SpO2 ≤90% as the oxygenation parameter. CURB-65 score is superior in the prediction of mortality.