Comparative epidemiology of atopic and non-atopic wheeze and diagnosed asthma in a national sample of English adults.
There is debate as to whether asthma has distinct atopic and non-atopic forms and whether in epidemiological studies asthma cases should be defined by a physician diagnosis or by self-reported asthma symptoms. A total of 24,952 people aged 11 and over were surveyed as part of the 1995-6 health surveys for England. Participants were asked if they had experienced wheezing in the past year and if they had ever been given a diagnosis of asthma by a doctor. Serum total IgE and house dust mite (HDM) specific IgE were measured. Wheeze in the past year without an asthma diagnosis was more common in men and older age groups, whereas wheeze with an asthma diagnosis was more common in women and younger people. Both types of wheeze were more common in the lower social classes, among ex-smokers and current smokers, and in urban areas. Thirty two percent of people reporting wheezing and 22% of those with diagnosed asthma had neither raised total IgE nor HDM IgE. Among the non-atopic subjects the prevalence of wheeze rose with age and lower social class, largely due to an increase in wheeze without diagnosed asthma. In contrast, among atopic subjects there was no overall trend with age or social class, but wheeze with diagnosed asthma decreased with age. Clear epidemiological differences are evident between adult wheeze with and without an asthma diagnosis and between atopic and non-atopic wheeze. Subjects with diagnosed asthma are more likely to be atopic, but the results challenge the premise that adult asthma is almost always associated with some IgE mediated reaction.