Does clinical presentation explain practice variability in the treatment of febrile infants?

BACKGROUND. Previous studies documented considerable variability in the treatment of febrile infants, despite the existence of practice guidelines for this condition. None of those studies documented the extent to which this variability is accounted for by differences in clinical severity. OBJECTIVE. To quantify the individual effects of the patient's clinical presentation, demographic, provider, and practice characteristics, and regional variables on practice variability in the evaluation and treatment of febrile infants. METHODS. With data collected through the Pediatric Research in Office Settings network, we analyzed data on the treatment of 2712 febrile infants examined by 484 pediatricians located in 194 practices. We analyzed hospitalization, lumbar puncture, urinalysis and/or urine culture, blood work, and initial antibiotic administration. We obtained a summary score for evaluation and treatment intensity (ranging from no tests or treatments to comprehensive testing, hospitalization, and antibiotic therapy) by performing principal-components analysis with these 5 variables. This summary score was regressed with respect to patients' clinical presentation, demographic and practice/practitioner features, and geographic region. Provider fixed effects were also included in the model. RESULTS. Although the overall model explained 46.5% of the variance, the clinical characteristics of the patient alone explained 29.7% of the overall variance. Practice site fixed effects explained nearly 15% of the overall variance. Provider and practitioner characteristics and geographic region had minimal explanatory power. CONCLUSIONS. Our results show that measures of the patient's clinical presentation account for nearly one third of the variability that our model explains. This suggests that differences in clinical presentation and severity of illness underlie much of the observed practice variability among pediatricians evaluating and treating febrile infants. These findings demonstrate that the management of this common and potentially serious condition depends more on the clinical presentation of the patient than on the characteristics of the provider/practice and the residential region.