Establishing clinically relevant standards for tachypnea in febrile children younger than 2 years
J. A. Taylor, M. Del Beccaro, S. Done and W. Winters
Department of Pediatrics, University of Washington, Seattle.
OBJECTIVE: To determine values for defining tachypnea in febrile children
younger than 2 years that best identify those at risk for pneumonia.
DESIGN: Prospective case series. STUDY PATIENTS: Children younger than 2
years presenting to the emergency department of a children's hospital with
a temperature of 38 degrees C or higher. INTERVENTIONS: Using a
standardized method, respiratory rates were obtained on eligible children
for 1 year. Study patients were classified as having pneumonia or no
pneumonia based on clinical evaluation and chest radiograph findings.
Receiver operating characteristic curves were constructed to select the
values for respiratory rate that maximized sensitivity and specificity of
tachypnea as a sign of pneumonia. RESULTS: Data were analyzed for 572
children; pneumonia was present in 42 (7%). The diagnostic utility of
tachypnea was maximal when cutoff values for respiratory rates of 59/min in
infants younger than 6 months, 52/min in those aged 6 through 11 months,
and 42/min in those aged 1 to 2 years were selected. Based on these
definitions, tachypnea as a sign of pneumonia had a sensitivity of 73.8%,
specificity of 76.8%, positive predictive value of 20.1%, and negative
predictive value of 97.4%. CONCLUSIONS: Tachypnea, as defined in this
study, is an important predictive sign of pneumonia in febrile children
younger than 2 years. Conversely, the absence of tachypnea obviates the
need for chest radiography in most settings.
