Obesity Predicts Shorter Time to First Exacerbation in Pediatric Patients with Uncontrolled Mild to Moderate Asthma

International audienceBackground: Although childhood obesity has been linked to poor asthma control, other studies have refuted this claim. Such inconsistencies may be due to the lack of clinical severity indicators and asthma diagnosis ascertainment in administrative databases; thus, the effect of weight status on asthma control remains to be elucidated in children using clinical data.Objectives: To assess if BMI percentile is a significant predictor of time to first exacerbation among children with mild to moderate uncontrolled asthma.Methods: We conducted a retrospective cohort study from clinical data linked to health and drug administrativedatabases. The cohort consisted of children aged 5-18 years with confirmed asthma, followed by theMontreal Children’s Hospital’s Asthma Center (AC) from January 1 2000 to September 31 2007 in QC, Canada. Patients were included at cohort entry if they were newly stepped-up to a higher-dose inhaled corticosteroid (ICS) monotherapy (MT) or ICS combination therapy (CT),i.e. with Long-Acting Beta2-Agonists or Leukotriene Receptor Antagonists as add-on therapies, from a low-dose ICS regimen. Exclusion criteria were: bronchopulmonary dysplasia, cystic fibrosis, or not covered by the public drug insurance plan. Patients were followed until the date of firstexacerbation, lost-to-follow-up or end of 1-year follow-up, whichever occurred first. Age- and sex-specific BMI percentiles were computed using the WHO growth charts at cohort entry and subsequent AC visits. Exacerbation was defined as any ED visit, hospitalization, or use of oral corticosteroids for asthma. A Cox model was used to determine the effect of time-varying BMI percentile on hazard of first exacerbation.Results: The final sample consisted of 355 children newly stepped-up to ICS MT (N=252) or ICS CT (N=103), with 234 (65.9%) events during follow-up. For every 10 unit increase in BMI percentile, the hazard of exacerbation increased by 31% (HR 1.31, 95% CI 1.20-1.43), after adjusting for confounders.Conclusions: Excess weight is an important predictor of exacerbation-free time in pediatric asthma. Further research is warranted to understand the pathology of obese-asthma in children