Radiographic Pneumonia in Febrile Infants 60 Days and Younger.

OBJECTIVE: Few prospective studies have assessed the occurrence of radiographic pneumonia in young febrile infants. We analyzed factors associated with radiographic pneumonias in febrile infants 60 days or younger evaluated in pediatric emergency departments.

STUDY DESIGN: We conducted a planned secondary analysis of a prospective cohort study within 26 emergency departments in a pediatric research network from 2008 to 2013. Febrile (≥38°C) infants 60 days or younger who received chest radiographs were included. Chest radiograph reports were categorized as "no," "possible," or "definite" pneumonia. We compared demographics, Yale Observation Scale scores (>10 implying ill appearance), laboratory markers, blood cultures, and viral testing among groups.

RESULTS: Of 4778 infants, 1724 (36.1%) had chest radiographs performed; 2.7% (n = 46) had definite pneumonias, and 3.9% (n = 67) had possible pneumonias. Patients with definite (13/46 [28.3%]) or possible (15/67 [22.7%]) pneumonias more frequently had Yale Observation Scale score >10 compared with those without pneumonias (210/1611 [13.2%], P = 0.002) in univariable and multivariable analyses. Median white blood cell count (WBC), absolute neutrophil count (ANC), and procalcitonin (PCT) were higher in the definite (WBC, 11.5 [interquartile range, 9.8-15.5]; ANC, 5.0 [3.2-7.6]; PCT, 0.4 [0.2-2.1]) versus no pneumonia (WBC, 10.0 [7.6-13.3]; ANC, 3.4 [2.1-5.4]; PCT, 0.2 [0.2-0.3]; WBC, P = 0.006; ANC, P = 0.002; PCT, P = 0.046) groups, but of unclear clinical significance. There were no cases of bacteremia in the definite pneumonia group. Viral infections were more frequent in groups with definite (25/38 [65.8%]) and possible (28/55 [50.9%]) pneumonias than no pneumonias (534/1185 [45.1%], P = 0.02).

CONCLUSIONS: Radiographic pneumonias were uncommon, often had viruses detected, and were associated with ill appearance, but few other predictors, in febrile infants 60 days or younger.