BACKGROUND: Childhood asthma is a common condition whose prevalence is changing. We hypothesised that the relationship between asthma and associated risk factors has changed over a 50-year period.
METHODS: An ecological study design was used. Children aged 8-13 attending schools in Aberdeen city were surveyed on seven occasions between 1964 and 2014. The following were determined: history of asthma, history of eczema, parental smoking, parental asthma, sex and socioeconomic status. Analysis was by a structural change model with two knots. The outcome reported was the change in odds ratio between asthma and a given risk factor during a given period.
RESULTS: There were 23,241 questionnaires distributed and 17,439 returned (75%). The odds ratio (OR) for a child with asthma to have eczema increased between 1989 and 1999 by 1.031 [95% CI 1.028, 1.035] and by 1.042 between 2004 and 2014 [1.038, 1.047].The OR for a child with asthma to have a parent who smoked rose by 1.032 [1.028, 1.036] between 1989 and 1999 and by 1.043 [1.038, 1.047] between 2004 and2014), and to have a parent with asthma (1.027 [1.022, 1.031] for 1994-99 and 1.042 [1.037, 1.048] for 2004-2014). The OR for a child with asthma being male and being from the most deprived communities also rose between 1989-1999 and 2004-2014.
CONCLUSIONS: The relationship between asthma prevalence and particular risk factors changed over the 50 year period of study and this might reflect changes in children's environment and/or susceptibility. This article is protected by copyright. All rights reserved.
Bibliographical noteWe acknowledge our funders Chest Heart and Stroke Scotland (grant number R14/A155) and a private donation from the family of Blanche Dawson, who conducted the 1964 Aberdeen Schools Asthma Survey. We thank the investigators of all past ASAS studies whose data we used in our analysis. Some of these past studies received funding from Allen and Hanburys, Astra and Novartis.
- child health
- environmental epidemiology