Temperature and Total White Blood Cell Count as Indicators of Bacteremia

Abstract

This study was designed to quantify more precisely the accuracy of magnitude of rectal temperature and total white blood cell (WBC) count as indicators of bacteremia in children with an obvious focal bacterial infection. A total of 955 children, aged 3 to 36 months, who had rectal temperature greater than or equal to 39.0 degrees C and were seeking care at either of two urban pediatric emergency departments had blood drawn for culture; 885 had blood drawn for WBC count. Twenty-seven had bacteremia. Various combinations of temperature and WBC count were selected to construct receiver-operating-characteristic curves by plotting sensitivity vs false-positive rate (1 - specificity). The receiver-operating-characteristic curve of WBC count provided significantly better diagnostic information than the curve for temperature increments above 39.0 degrees C. Each increment of 0.5 degrees C led to large decrements in sensitivity and false-positive rates. At a WBC count cutoff of 10,000/mm3, the sensitivity was 92% while the false-positive rate was 57%. Using this cutoff point, the clinician could have avoided performing 368 of 955 blood cultures and missed only 2 of 26 children with bacteremia. Receiver-operating-characteristic curves combining WBC count and temperature increments above 39.0 degrees C provided no better diagnostic information than that of WBC count at a temperature cutoff of 39.0 degrees C. It is concluded that increments in temperature above 39.0 degrees C provided additional diagnostic specificity for bacteremia only at the expense of unacceptable decreases in sensitivity. Total WBC count provided better information. A WBC count cutoff of 10,000/mm3 increased specificity with minimal decrease in sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)