Predictors from multivariate analysis:
(1) a decrease in the percent SaO2 by >= 10%
(2) high flow rates of supplementary nasal oxygen
Rules developed to identify a patient requiring admission to the ICU:
(1) nasal oxygen flow rate >= 3 L/min to maintain SpO2 >= 92%
(2) 2 or more involved quadrants on the first chest X-ray (maximum 4)
Performance:
(1) The first rule had a sensitivity of 76% and specificity of 96%.
(2) The 2 rules together had a sensitivity of 84% and specificity of 97%. This had a PPV of 91% and a NPV of 96%.
Additional risk factors for ICU admission:
(1) presence of hepatic failure
(2) Gram-negative bacteria isolated in blood cultures (pathogenic Gram-positive bacteria should also be significant)
(3) 2 or more organ failures
(4) low PaO2 (mean 62 mm Hg)
