The predictive performance of a pneumonia severity score in HIV-negative children presenting to hospital in seven low and middle-income countries

Background: In 2015, pneumonia remained the leading cause of mortality in children between 1-59 months old. Methods: Data from 1802 HIV-negative children between 1-59 months old enrolled in the Pneumonia Etiology Research for Child Health (PERCH) study with severe or very severe pneumonia during 2011-14 were used to build a parsimonious multivariable model predicting mortality using backwards stepwise logistic regression. The PERCH severity score, derived from model coefficients, was validated on a second, temporally discrete dataset of a further 1819 cases and compared to other available scores using the c-statistic. Results: Predictors of mortality, across seven low and middle-income countries, were: age <1 year, female sex, 3 or more days of illness prior to presentation to hospital, low weight-for-height, unresponsiveness, deep breathing, hypoxemia, grunting and the absence of cough. The model discriminated well between those who died and those who survived (c-statistic: 0.84), but the predictive capacity of the PERCH 5-stratum score derived from the coefficients was moderate (c=0.76). The performance of the Respiratory Index of Severity in Children (RISC) score was similar (c=0.76). The number of WHO danger signs demonstrated the highest discrimination (c=0.82; 1.5% died if no danger signs, 10% if 1 danger sign and 33% if 2 or more danger signs). Conclusions: The PERCH severity score could be used to interpret geographic variations in pneumonia mortality and etiology. The number of WHO danger signs on presentation to hospital could be the most useful, of the currently available tools, to aid clinical management of pneumonia.