Occult pneumonias: Empiric chest radiographs in febrile children with leukocytosis

Study objective: We sought to determine the incidence of radiographic findi ngs of pneumonia in highly febrile children with leukocytosis and no clinic al evidence of pneumonia or other major infectious source. Methods: We conducted a prospective cohort study at a large urban pediatric hospital. Clinical practice guidelines for the use of chest radiography in febrile children were established by the emergency medicine attending staf f. All records of emergency department patients with leukocytosis (WBC coun t greater than or equal to 20,000/mm(3)), triage temperature 39.0 degrees C or higher, age 5 years or less were reviewed daily for 12 months. Physicia ns completed a questionnaire to note the diagnosis, the presence of respira tory symptoms and signs, and the reason for the chest radiograph (if one wa s obtained). Patients were excluded for immunodeficiency, chronic lung dise ase, or major bacterial sources of infection other than pneumonia. Pneumoni a was defined by an attending radiologist's reading of the radiograph. Results: We studied 278 patients. Chest radiographs were obtained in 225 fo r the following reasons: 79 because of respiratory findings suggestive of p neumonia and 146 because of leukocytosis and no identifiable major source o f infection. Fifty-three patients did not undergo radiography. Pneumonia wa s found in 32 of 79 (40%; 95% confidence interval, 20% to 52%) of those wit h findings suggestive of pneumonia and in 38 of 146 (26%; 95% confidence in terval, 19% to 34%) of those without clinical evidence of pneumonia. If pat ients who did not have a radiograph are assumed to not have pneumonia, the minimum estimate of occult pneumonia was 38 of 199 patients (19%; 95% confi dence interval, 14% to 25%). Conclusion: Empiric chest radiographs in highly febrile children with leuko cytosis and no findings of pneumonia frequently reveal occult pneumonias. C hest radiography should be considered a routine diagnostic test in children with a temperature of 39 degrees C or greater and WBC count of 20,000/mm(3 ) or greater without an alternative major source of infection.