PREDICTORS OF OCCULT PNEUMOCOCCAL BACTEREMIA IN YOUNG FEBRILE CHILDREN

Study objective: Occult pneumococcal bacteremia (OPB) occurs in 2.5% t o 3% of highly febrile children 3 to 36 months of age, and 10% to 25% of untreated patients with OPB experience complications, including 3% to 6% in whom meningitis develops. The purpose of this study was to id entify predictors of OPB among a large cohort of young, febrile childr en treated as outpatients using multivariable statistical methods. Met hods: We derived and validated a logistic regression model for the pre diction of OPB. We evaluated 6,579 outpatients 3 to 36 months of age w ith temperatures of 39 degrees C or higher who previously had been enr olled in a study of young febrile patients at risk of OPB in the emerg ency departments of 10 hospitals in the United States between 1987 and 1991; 164 patients (2.5%) had OPB. We randomly selected two thirds of this population for the derivation of the model and one third for val idation. In the derivation set, we analyzed the univariate relationshi ps of six variables with OPB: age, temperature, clinical score, WBC co unt, absolute neutrophil count (ANC), and absolute band count (ABC). A ll six variables were then entered into a logistic regression equation and those retaining statistical significance were considered to have an independent association with OPB. Results: Patients with OPB were y ounger, more frequently ill-appearing, and had higher temperatures, WB C, ANC, and ABC than patients without bacteremia. Only three variables , however, retained statistically significant associations with OPB in the multivariate analysis: ANC (adjusted odds ratio [OR] 1.15 for eac h 1,000 cells/mm(3) increase, 95% confidence interval [CI] 1.06, 1.25) , temperature (adjusted OR 1.77 for each 1 degrees C increase, 95% CI 1.21, 2.58), and age younger than 2 years (adjusted OR 2.43 versus pat ients 2 to 3 years old, 95% CI interval 1.11, 5.34). In the derivation set, 8.1% of patients with ANCs greater than or equal to 10,000 cells /mm(3) had OPB (95% CI 6.3, 10.1%) versus .8% of patients with ANCs le ss than 10,000 cells/mm(3) (95% CI .5, 1.2%). When tested on the valid ation set, the model performed similarly. Conclusion: Independent pred ictors of OPB in children 3 to 36 months of age with temperatures of 3 9 degrees C or higher treated as outpatients include ANC, temperature, and age younger than 2 years. These predictors may be used to develop clinical strategies to limit laboratory testing and antibiotic admini stration to those children at greatest risk of OPB.