Association Between Outdoor Air Pollution Levels and Inpatient Outcomes in Pediatric Pneumonia Hospitalizations, 2007 to 2008

OBJECTIVE: Pneumonia is a leading cause of pediatric admissions. Although air pollutants are associated with poor outcomes, few national studies have examined associations between pollutant levels and inpatient pediatric pneumonia outcomes. We examined the relationship between ozone (O-3) and fine particulate matter with a diameter <= 2.5 mu m (PM2.5) and outcomes related to disease severity. METHODS: In this cross-sectional study, we obtained discharge data from the 2007 to 2008 Nationwide Inpatient Sample and pollution data from the Air Quality System. Patients <= 18 years with a principal diagnosis of pneumonia were included. Discharge data were linked to O-3 and PM2.5 levels (predictors) from the patient's ZIP Code (not publicly available) from day of admission. Outcomes were mortality, intubation, length of stay (LOS), and total costs. We calculated weighted national estimates and performed multivariable analyses adjusting for sociodemographic and hospital factors. RESULTS: There were a total of 57,972 (278,871 weighted) subjects. Median PM2.5 level was 9.5 (interquartile range [IQR] 6.8-13.4) mu g/m(3). Median O-3 level was 35.6 (IQR 28.2-45.2) parts per billion. Mortality was 0.1%; 0.75% of patients were intubated. Median LOS was 2 (IQR 2-4) days. Median costs were $3089 (IQR $2023-$5177). Greater levels of PM2.5 and O-3 were associated with mortality, longer LOS, and greater costs. Greater O-3 levels were associated with increased odds of intubation. CONCLUSIONS: Greater levels of O-3 and PM2.5 were associated with more severe presentations of pneumonia. Future work should examine these relationships in more recent years and over a longer time period.