How are 'urban' and 'rural' defined in publications regarding asthma and related diseases?

BACKGROUND

Global variations in the prevalence of asthma and related diseases have suggested that environmental factors are causative, and that factors associated with urbanisation are of particular interest. A range of definitions for 'urban' and 'rural' have been used in articles on asthma and related diseases, making it difficult to assess their importance as aetiological factors. This study sets out to examine such definitions used in the literature.

METHODS

Medical and social science databases were searched for articles that made distinctions of 'urban' and/or 'rural' in the context of asthma and related diseases.

RESULTS

The search identified 73 articles and categorised four types of definitions. A specific definition of urban or rural was used in 19 (26%) articles. Nine (12%) articles used non-specific and/or administrative definitions. There were 23 (32%) articles that described locations as 'urban' or 'rural' but did not indicate if the description defined 'urban' or 'rural'. Distinctions were made between urban and rural locations without a description or definition in 22 (30%) articles.

CONCLUSIONS

There is substantial variation in the definitions of 'urban' and 'rural' in articles regarding asthma and related diseases. It would be advantageous to have clearer and more precise definitions of 'urban' and 'rural' which could facilitate aetiological research and also comparisons between locations, especially in international studies.