Table 4

Prediction of invasive mechanical ventilation by oxygenation indices and CURB-65

Se (%)Sp (%)PPV (%)NPV (%)LR+LR−AUROC95% CIP value
PaO2:FiO277.254.816.595.51.720.410.700.62 to 0.78<0.001
A/a gradient56.688.536.194.64.900.490.100.61 to 0.78<0.001
a/A index75.058.817.395.31.820.430.680.59 to 0.77<0.001
ROX index from SpO277.862.419.396.02.070.360.730.67 to 0.79<0.001
CURB-6513.694. to 0.590.030
  • A/a gradient, alveolar-arterial oxygen gradient; a/A index, arterial-alveolar oxygen tension ratio; AUROC, area under the curve of receiver operating characteristics; CURB-65, confusion, urea level, respiratory rate, systolic or diastolic blood pressure, 65 years or older; LR−, likelihood ratio of a negative test; LR+, likelihood ratio of a positive test; NPV, negative predictive value ; PaO2:FiO2, ratio of arterial oxygen pressure to fraction of inspired oxygen; PPV, positive predictive value; ROX index, Respiratory rate-OXygenation index; Se, sensitivity; Sp, specificity; SpO2, oxygen saturation.