Initial oxygen saturation as a predictor of admission in children presenting to the emergency department with acute asthma

Background: Previous studies have looked at the relationship between initial oxygen saturation (SaO(2)) and the need for admission in children presenting with an acute asthma exacerbation. If initial SaO(2) value is indeed predictive of admission, then the admission process could be initiated sooner, and time spent in the emergency department could be potentially lessened. Study objective: The objective of the current study was to examine whether initial room air SaO(2) in children presenting to the ED with acute asthma is a reliable predictor of hospital admission. Methods: This was a prospective multicenter study during 1997 and 1998 at 44 North American EDs as part of the Multicenter Airway Research Collaboration. Inclusion criteria were physician diagnosis of acute asthma and age between 2 and 17 years. The association between hospital admission and SaO(2) was examined by using logistic regression. Likelihood ratios were used to assess the diagnostic value of SaO(2). Results: Of the 1,184 children enrolled in the current study, 1,040 (88%) had a documented initial SaO(2) value on room air. The mean age of the cohort was 8 4 years, with a mean initial SaO(2) of 95%+/-4%. Overall, 241 (23%) children were admitted to the hospital. The mean SaO(2) value of children admitted to the hospital was 93%+/-5% versus 96%+/-3% for those not admitted (P<.001). The admission rate decreased with increasing SaO(2); 73% (30/41) of children with an Sa value of 88% or less were admitted versus 8% (7/88) with an SaO(2) value of 100%. In the logistic regression model, children with an SaO(2) value of 88% or less were 32 (95% confidence interval 11 to 89) times more likely to be admitted than those with an SaO(2) value of 100%. The likelihood ratio for admission was 12 for children with an Sa value of 88% or less (42/1,040) but decreased to 4.6 for children with an SaO(2) value of 91% or less (130/1,040) and 2.7 for children with an SaO(2) value of 94% or less (333/1,040). Conclusion: This large, clinical multicenter study does not support earlier findings that SaO(2) alone is a clinically useful predictor of hospital admission in children who present to the ED with acute asthma.