Yale observation scale for prediction of bacteremia in febrile children

Abstract

Objective

To assess the accuracy and reliability of yale observation scale (YOS) predicting bacteremia.

Methods

219 consecutive febrile inpatients aged 3–36 months were the subjects. Before giving antipyretics, rectal temperature was recorded. YOS scores were assessed by 2 independent blinded residents. History, clinical examination and investigations followed. Blood cultures were taken in all children before antibiotics. Point estimates and 95% confidence intervals were calculated for sensitivity, specificity, positive & negative predictive values and likelihood ratios for use of YOS as a diagnostic test in prediction of bacteremia. The best cut off value for a positive YOS test was established by calculating these statistical values separately for a cut off YOS score of 8, 10 and 12 and plotting ROC curve. Reliability of YOS was assessed by the inter-observer agreement through kappa statistics.

Results

Study population (n=219) had 59.36% males and a mean age of 15.24 months. 28.16% subjects had bacteremia. Mean YOS scores were significantly higher in bacteremic children (14.9 vs 8.78 in non-bacteremic, p=0.00001) Sensitivity, specificity, PPV, NPV, LR+ and LR− of YOS score >10 to predict bacteremia were 87.93%, 83.78%, 68.00%, 94.66%, 5.42 and 0.14 respectively. Those of YOS score >8 were 96.55%, 65.54%, 52.34%, 97.98%, 2.80 and 0.05 respectively and of a YOS score >12 were 48.28%, 91.22%, 68.29%, 81.82%, 5.5 and 0.5 respectively. ROC curve showed YOS score >10 to be the best cut off for prediction of bacteremia. Area under ROC curve was 0.9001. The chance corrected inter-observer agreement (kappa) was 0.7919.

Conclusion

YOS is a simple, easy to administer, cost-effective and useful test to predict bacteremia in a febrile child aged 3–36 months due to its high sensitivity and reproducibility.