Assessment of a simple scoring system applied to a screening questionnairefor asthma in children aged 5-15 yrs

The aim of the present study was to validate a simple scoring system using a parent-completed screening questionnaire to identify children aged 5-15 y rs who may have asthma. A stratified random sample of 157 children of 1,808 whose parents had answe red a postal respiratory questionnaire underwent detailed clinical evaluati on. The results were reviewed by three independent paediatricians whose opi nions were combined to reach, for each child, decisions regarding three sta ndards: 1) "possible asthma" defined as >50% likelihood of having asthma; 2 ) "possible asthma" defined as meriting a clinical trial of asthma medicati on; and 3) "probable asthma" defined as >90% likelihood of having asthma. T he combined decisions were compared to three sets of questionnaire scores, in order to determine the positive predictive value, sensitivity and specif icity of each set in identifying children with probable/possible asthma. The three sets of chosen questionnaire scores all had positive predictive v alues of 79-96% for predicting possible asthma, using either the combined e xpert opinion ">50% likelihood of asthma" or that of "warrants a trial of t reatment" as the definition. This suggests that a low proportion of false p ositives would be obtained were this scoring system to be used for a screen ing programme. The combined decision >90% chance of asthma could be used as a means of estimating prevalence of asthma in the survey. When used for th is, the prevalence of asthma in the surveyed population was 18.8% (95% conf idence interval 13.1-26.3). In conclusion, the present scoring system, based on a simple respiratory qu estionnaire, provides a valid method of identifying children likely to have asthma, and who, if unknown to the medical services, would benefit from cl inical review.