Early life BMI progression and asthma incidence

Results from an interesting epidemiological investigation based on data from eight birth cohorts collected under the Global Allergy and Asthma European Network [GA²LEN] research initiatives are presented this month in Rzehak et al (J Allergy Clin Immunol 2013; 131(6): 1528-1536).  Risk of “incident asthma,” defined as first reported physician diagnosis, for 3 age brackets up to 6 years old is analyzed.

Using a novel growth curve analysis method to identify classes of BMI trajectories normalized according to WHO standards [BMI-SDS], the authors identify three classes, a normative class [Class 1], an early rapid growth only up to 2 years class [Class 2], and a persistent rapid growth to 6 years class [Class 3].  Survival analysis of the three BMI-SDS trajectories assessed the hazard ratio [HR] for incident asthma in each. 

Rzehak et al. report that children in the Class 2 trajectory had a significant increased risk of incident asthma within their first 6 years.  Class 3 children had similar risk that did not achieve significance.  Hazard ratios were similar between Class 2 and 3, the latter class having a greater prevalence of excess weight and obesity, suggesting that there is an association of early rapid weight gain with incident asthma, independent of overweight or obesity.

Rzehak et al. conclude that rapid weight gain during the first two years of life increases the risk of incident asthma by the age of 6 years.