Asthma score: predictive ability and risk factors

Definition of asthma as a continuous score is a promising tool for population studies that has not yet been fully evaluated.

We assessed (i) the predictive ability of an asthma score against the occurrence of different asthma-related outcomes and (ii) the risk factors identified when using an asthma score.

The European Community Respiratory Health Study II included subjects from the general population randomly studied during 1991-1993 who were followed up in the years 1998-2001, from 29 centres in 14 countries. A total of 8956 subjects were included. The asthma score consisted of a simple sum of the positive answers to five respiratory symptoms.

Asthma score at baseline showed a linear relationship with incidence of asthma, the occurrence of asthma attacks, use of asthma medication and bronchial reactivity at the end of the follow-up. Asthma score at the end of follow-up was associated with known risk factors at baseline such as IgE to grass, rhinitis or body mass index, in addition to passive smoking in men [average score ratio (RR) = 1.30; 95% confidence interval (CI) 1.09-1.50] or changes in body mass index (RR = 1.27; 95% CI 1.05-1.27, per each kg/m(2)).

The asthma score had good predictive ability against outcomes related with asthma and also good ability to detect risk factors. This encourages the use of the score as a measure of asthma in epidemiological studies on aetiology of asthma.