Background PaO2 /FIO2 (P/F) ratio has been used to define the severity of acute respiratory distress syndrome (ARDS) despite the controversy of its clinical utility. This systematic review and meta-analysis (SRMA) aimed to obtain summary estimates of predictive performance of the P/F ratio for predicting mortality in ARDS patients. Methods We included a study wherein the study population comprised ARDS patients in any clinical setting. Medline and Cochrane Central Registry of Controlled Trials were searched for all English language articles. We performed a SRMA on the accuracy of diagnostic prognostic tests using QUADAS-2 tool to evaluate the risk of bias. To pool the results, we applied the bivariate model and obtained summary point estimates of sensitivity and specificity with 95% CIs. Results Twenty-eight trials and 38270 patients were included in the meta-analysis. Most of the study settings were in the intensive care units. The overall risk of bias was high. The pooled sensitivity of the P/F ratio in all included studies for a P/F ratio of 100 was 43.6% (95% CI, 36.9-50.5%) and the specificity was 71.1% (95% CI, 66.7-75.1%) and those for a P/F ratio of 200 were 83.2% (95% CI, 78.2-87.2%) and 26.2% (95% CI, 21.2-31.9%). Interpretation The P/F ratio had high sensitivity and moderate specificity at a P/F ratio of 200 and 100 respectively, which supports the use of the P/F ratio for screening ARDS patients who are at risk of deterioration.Trial registration: The study was registered in UMIN with registration number 64 000041058.
