ESTABLISHING CLINICALLY RELEVANT STANDARDS FOR TACHYPNEA IN FEBRILE CHILDREN YOUNGER THAN 2 YEARS

Objective: To determine values for defining tachypnea in febrile child ren younger than 2 years that best identify those at risk for pneumoni a. Design: Prospective case series. Study Patients: Children younger t han 2 years presenting to the emergency department of a children's hos pital with a temperature of 38 degrees C or higher. Interventions: Usi ng a standardized method, respiratory rates were obtained on eligible children for 1 year. Study patients were classified as having pneumoni a or no pneumonia based on clinical evaluation and chest radiograph fi ndings. Receiver operating characteristic curves were constructed to s elect the values for respiratory rate that maximized sensitivity and s pecificity of tachypnea as a sign of pneumonia. Results: Data were ana lyzed for 572 children; pneumonia was present in 42 (7%). The diagnost ic utility of tachypnea was maximal when cutoff values for respiratory rates of 59/min in infants younger than 6 months, 52/min in those age d 6 through 11 months, and 42/min in those aged 1 to 2 years were sele cted. Based on these definitions, tachypnea as a sign of pneumonia had a sensitivity of 73.8%, specificity of 76.8%, positive predictive val ue of 20.1%, and negative predictive value of 97.4%. Conclusions: Tach ypnea, as defined in this study, is an important predictive sign of pn eumonia in febrile children younger than 2 years. Conversely, the abse nce of tachypnea obviates the need for chest radiography in most setti ngs.