Effect of context on respiratory rate measurement in identifying non-severe pneumonia in African children

Florida Muro, George Mtove, Neema Mosha, Hannah Wangai, Nicole Harrison, Helena Hildenwall, David Schellenberg, Jim Todd, Raimos Olomi andHugh Reyburn
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Cough or difficult breathing and an increased respiratory rate for their age are the commonest indication for outpatient antibiotic treatment in African children. We aimed to determine if respiratory rate was likely to be transiently raised by a number of contextual factors in a busy clinic leading to inaccurate diagnosis.


Respiratory rates were recorded in children aged 2-59 months presenting with cough or difficulty breathing to one of the two busy outpatient clinics and then repeated at 10-minute intervals over 1 hour in a quiet setting.


167 children were enrolled with a mean age of 7.1 (SD±2.9) months in infants and 27.6 (SD±12.8) months in children aged 12-59 months. The mean respiratory rate declined from 42.3 and 33.6 breaths per minute (bpm) in the clinic to 39.1 and 32.6 bpm after 10 minutes in a quiet room and to 39.2 and 30.7bpm (p<0.001) after 60 minutes in younger and older children respectively. This resulted in 11/13 (85%) infants and 2/15 (13%) older children being misclassified with non-severe pneumonia. In a random effects linear regression model the variability in respiratory rate within-children (42%) was almost as much as the variability between children (58%). Changing the respiratory rates cut-offs to higher thresholds resulted in a small reduction in the proportion of non-severe pneumonia mis-classifications in infants.


Noise and other contextual factors may cause a transient increase in respiratory rate and consequently misclassification of non-severe pneumonia. However, this effect is less pronounced in older children than infants. Respiratory rate is a difficult sign to measure as the variation is large between and within children. More studies of the accuracy and utility of respiratory rate as a proxy for non-severe pneumonia diagnosis in a busy clinic are needed.