Continue Chest X-Rays in Highly Febrile Children With Leukocytosis Radiographic Pneumonia in Young, Highly Febrile Children With Leukocytosis Before and After Universal Conjugate Pneumococcal Vaccination

Background: Diagnosis of bacterial illness in young children is difficult. Most children with fever and illness have a viral etiology, but a small number may have pneumonia. The efficacy of a chest x-ray has been debated in the workup of fever in children. Before the pneumococcal conjugate vaccine (PCV) was introduced, the incidence of non-occult pneumonia was thought to be 40%; occult pneumonia had an incidence of 19% in children with concerning laboratory values. This has declined significantly since the vaccine was introduced. Objective: To determine the impact of the pneumococcal vaccine in the incidence of occult and non-occult pneumonia as diagnosed by radiograph. Design/Participants: Retrospective cohort study of emergency department records in a pediatric hospital. Patients were eligible if they were aged <5 years and had presented between 1996 and 2005 with a temperature >39°C, had a white blood cell count ≥20,000/μL, and had a chest x-ray performed. Those with an identifiable source of infection other than pneumonia were excluded. Methods: Patients were stratified into 2 groups (before and after universal use of PCV). Pneumonia was defined as a focal infiltrate (or consolidation) on chest x-ray as read by a radiologist. Occult pneumonia was defined as diagnosis of pneumonia by radiograph without clinical respiratory symptoms. Results: Of >235,000 children aged <5 years seen in the emergency department over a 10-year period, 889 met criteria for the cohort in the pre-PCV era and 335 met criteria in the post-PCV era. This was due in part to the significant decrease in the number of complete blood cell counts performed since PCV was introduced. Pneumonia was seen on x-ray in 21% of children pre-PCV and 18% after. Occult pneumonia was diagnosed in 15% of children pre-PCV and 9% after. When looking only at children aged <2 years, radiographic pneumonia was diagnosed in 17% pre-PCV and 10% after. Conclusions: Pneumonia rates, while decreasing a bit, may still be high enough to continue to warrant chest radiographs in children with high fevers, leukocytosis, and no other source of infection. The incidence of pneumonia as diagnosed by chest x-ray has declined a bit since the introduction of PCV, but the incidence is still reasonably high. The decrease is likely not significant enough to warrant changing current recommendations. Reviewer's Comments: I was surprised that the incidence of pneumonia did not change more than it did. However, I was surprised that is was as high as it was at all. Still, this paper does not give enough new evidence to warrant changing the recommendation. (Reviewer-Aaron E. Carroll, MD, MS).