Prediction of bacteremia in the emergency department: an external validation of a clinical decision rule

Objective The objective of this study was to validate a previously published clinical decision rule for predicting a positive blood culture in emergency department (ED) patients with suspected infection on the basis of major and minor criteria and a total score (Shapiro et al., J Emerg Med, 2008; 35:255-264). Methods This is a retrospective matched cohort study of adult ED patients with blood cultures obtained from 1 January 2011 through to 31 December 2011. ED patients with blood culture-confirmed bacteremia were matched 1 : 3 with patients with negative cultures. The outcome was 'true bacteremia'. Data on clinical history, comorbid illnesses, physical observations, and laboratory tests were used to evaluate the application of the clinical decision rule. We report the sensitivity, specificity, and area under the curve. Results Among 1526 patients, 105 (6.9%) patients were classified with true bacteremia. The sensitivity of the prediction rule was 94% (95% confidence interval, 88-98%) and the specificity was 48% (95% confidence interval, 42-53%). The area under the receiver-operating characteristics curve was 0.83. Conclusion The clinical decision rule performed well in our ED setting and is likely to be a useful supplement to clinical judgment.