Thorax 56:845-850 doi:10.1136/thorax.56.11.845
  • Original article

Can the increase in body mass index explain the rising trend in asthma in children?

  1. S Chinn,
  2. R J Rona
  1. Department of Public Health Sciences, King's College London, London SE1 3QD, UK
  1. Miss S Chinnsue.chinn{at}
  • Received 16 February 2001
  • Revision requested 25 June 2001
  • Revised 4 July 2001
  • Accepted 25 July 2001


BACKGROUND The reported association between asthma and obesity and the documented rise in each over time have led to suggestions that rising obesity might explain the increase in the prevalence of asthma. Trends in both in British children participating in the National Study of Health and Growth were marked from 1982 to 1994.

METHODS Odd ratios for trends in asthma and symptoms in 8 and 9 year old children were calculated with and without adjustment for body mass index (BMI).

RESULTS In a representative sample of white children the odds ratio per year for asthma was 1.09 (95% CI 1.07 to 1.11) before and after adjustment for BMI for boys and 1.09 (95% CI 1.07 to 1.12) and 1.09 (95% CI 1.05 to 1.12), respectively, for girls. Unadjusted and adjusted odds ratios were also virtually identical for wheeze and “asthma or bronchitis”. The lack of effect of adjustment was due to a change in the association between BMI and symptoms with time.

CONCLUSIONS Trends in overweight and obesity do not explain the increase in asthma. The evidence points towards the association between asthma and obesity being of recent origin. This may be explained by obesity being a marker of recent lifestyle differences now associated with both asthma and overweight.