Temperature-Adjusted Respiratory Rate for the Prediction of Childhood Pneumonia.

OBJECTIVES

As both fever and pneumonia can be associated with tachypnea, we investigated the relationship between body temperature and respiratory rate (RR) in young children and whether temperature-adjusted RR enhances the prediction of pneumonia.

METHODS

In this retrospective cross-sectional analysis of 91,429 children < 5 years of age presenting to an urban pediatric emergency department, the relationship between triage RR and temperature was analyzed using regression analysis. We assessed the predictive value of temperature-adjusted RR for the diagnosis of pneumonia; diagnostic performance was evaluated for continuous RR as well as World Health Organization (WHO) age-based RR thresholds.

RESULTS

The mean RR increased 2.6 breaths/minute for each 1°C increase in temperature. Interpatient variability was comparatively large; at any temperature, the interquartile range (75th percentile minus 25th percentile) varied from 4 to 16 breaths/minute. For predicting pneumonia, temperature- and age-adjusted RR was superior to age-adjusted RR: area under the curve (AUC) = 0.76 (95% confidence interval [CI], 0.75-0.78) versus AUC = 0.73 (95% CI, 0.72-0.75), respectively. Using WHO RR criteria, temperature-adjusted RR improved diagnostic discrimination, as the AUC increased from 0.58 (95% CI, 0.57-0.59) to 0.72 (95% CI, 0.70-0.73).

CONCLUSIONS

The effects of temperature on respiratory rate are modest, with a mean increase of 2.6 breaths/minute for each 1°C rise in temperature. Despite considerable interpatient variability in respiratory rates by temperature, temperature adjustment improves the diagnostic value of respiratory rate for pneumonia.