CLINICAL-SIGNIFICANCE OF COUGH AND WHEEZE IN THE DIAGNOSIS OF ASTHMA

Objectives-(1) To determine the prevalence of cough, wheeze, and breat hlessness, both as single symptoms and in combination, in primary scho olchildren and their relation to doctor diagnosed asthma. (2) To ident ify in areas with different levels of dust pollution whether questionn aire reported 'cough alone' (without wheeze or breathlessness) had sim ilar risk factors to the questionnaire reported triad of (cough, wheez e, and breathlessness'. Subjects and methods-Two cross sectional commu nity surveys of primary schoolchildren (5-11 years) were performed in 1991 and 1993. Parent completed questionnaires related to socioeconomi c and respiratory factors were distributed through 15 schools in three areas of Merseyside, one of which had a relatively high level of dust pollution. Data were analysed to determine the prevalence of differen t respiratory symptom patterns. Univariate and multiple logistic regre ssions were used to investigate the associations between respiratory s ymptom profiles and potential risk factors. Results-The proportions of completed questionnaires that were returned were similarly high in bo th surveys, 92% in 1991 (1872 of 2035) and 87% in 1993 (3746 of 4288). The proportions of children with different respiratory symptom patter ns were similar in the two surveys: in 1991, asymptomatic children 70. 1% (1109 of 1583), those with cough alone 8.9% (141 of 1583), and chil dren with the symptom triad of cough, wheeze, and breathlessness 8.3% (132 of 1583); the figures for 1993 were 69.5% (2144 of 3083), 9.2% (2 84 of 3083), and 7.3% (224 of 3083) respectively. The prevalence of do ctor diagnosed asthma increased from 17.4% in 1991 to 22.1% in 1993. T he symptom of cough alone was associated with going to school in an ar ea of increased air pollution. The symptom triad of cough, wheeze, and breathlessness was associated with reported allergies, familial histo ry of atopy and preterm birth. In 1991, of children with the symptom o f cough alone one in eight were diagnosed asthmatic; twice as many doc tors made the diagnosis on this basis in 1993. Conclusion The respirat ory symptom of cough alone and cough, wheeze, and breathlessness repre sent clinical responses to different specific risk factors. Cough alon e was associated with the environmental factors of school in the dust exposed zone and dampness in the home, whereas cough, wheeze, and brea thlessness related to allergic history and preterm birth, and may be t he best surrogate of asthma. Diagnosis of asthma on the basis of cough alone partly explains the increased prevalence of doctor diagnosed as thma, especially in dust polluted areas.