Ethnic variation in respiratory morbidity and lung function in childhood.

In a population of 5689 primary schoolchildren there were few important differences between children of European (n = 5287), African (n = 198), and Indian origin (n = 204) in the prevalence of a history of past respiratory illnesses or current respiratory symptoms. The reported 12 month period prevalence of the symptom "ever wheezy" was 15%, 18%, and 17% respectively in the three ethnic groups (differences not significant). In a subsample of 973 European, 47 African, and 40 Indian children forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were significantly lower by 12% and 13% in Africans and by 8% and 9% in Indians than in Europeans after adjustment to the group mean height of 128 cm. No significant ethnic variation was found for forced mid expiratory flow, FEV1/FVC, or mean transit time. Since the lung function studies were performed on a sample from a large population with little variation in respiratory morbidity, the differences are likely to reflect human biological differences. Separate prediction equations need to be developed for the different ethnic groups in childhood.