Asthma trajectories in early childhood: identifying modifiable factors

PLoS One. 2014 Nov 7;9(11):e111922. doi: 10.1371/journal.pone.0111922. eCollection 2014.

Abstract

Background: There are conflicting views as to whether childhood wheezing represents several discreet entities or a single but variable disease. Classification has centered on phenotypes often derived using subjective criteria, small samples, and/or with little data for young children. This is particularly problematic as asthmatic features appear to be entrenched by age 6/7. In this paper we aim to: identify longitudinal trajectories of wheeze and other atopic symptoms in early childhood; characterize the resulting trajectories by the socio-economic background of children; and identify potentially modifiable processes in infancy correlated with these trajectories.

Data and methods: The Millennium Cohort Study is a large, representative birth cohort of British children born in 2000-2002. Our analytical sample includes 11,632 children with data on key variables (wheeze in the last year; ever hay-fever and/or eczema) reported by the main carers at age 3, 5 and 7 using a validated tool, the International Study of Asthma and Allergies in Childhood module. We employ longitudinal Latent Class Analysis, a clustering methodology which identifies classes underlying the observed population heterogeneity.

Results: Our model distinguished four latent trajectories: a trajectory with both low levels of wheeze and other atopic symptoms (54% of the sample); a trajectory with low levels of wheeze but high prevalence of other atopic symptoms (29%); a trajectory with high prevalence of both wheeze and other atopic symptoms (9%); and a trajectory with high levels of wheeze but low levels of other atopic symptoms (8%). These groups differed in terms of socio-economic markers and potential intervenable factors, including household damp and breastfeeding initiation.

Conclusion: Using data-driven techniques, we derived four trajectories of asthmatic symptoms in early childhood in a large, population based sample. These groups differ in terms of their socio-economic profiles. We identified correlated intervenable pathways in infancy, including household damp and breastfeeding initiation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Asthma / epidemiology*
  • Asthma / etiology
  • Asthma / physiopathology
  • Breast Feeding
  • Child
  • Child, Preschool
  • Cluster Analysis
  • Cohort Studies
  • England / epidemiology
  • Female
  • Housing
  • Humans
  • Infant
  • Longitudinal Studies
  • Male
  • Models, Statistical
  • Phenotype
  • Prevalence
  • Respiratory Sounds
  • Risk Factors
  • Social Class

Grant support

The Millennium Cohort Study is funded by the Economic and Social Research Council (ESRC), UK. This work was partly funded by the ESRC International Centre for Lifecourse Studies in Society and Health (RES-596-28-0001). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.