NAC Manchester Asthma and Allergy Study (^NACMAAS): risk factors for asthma and allergic disorders in adults

Abstract

Asthma and atopic disorders are the most common chronic diseases in the developed countries. Knowledge of the risk factors for these disorders may facilitate the development of preventive strategies aimed at reducing prevalence rates. To investigate the risk factors for asthma and allergic diseases in a large number of adults who are the parents of children in the National Asthma Campaign Manchester Asthma and Allergy Study. All pregnant women and their partners attending "Booking" antenatal clinics were invited to take part in the study. Questionnaire data were collected including the history of asthma and other atopic diseases, pet ownership and smoking habits, and skin prick tests were performed. The prevalence of atopy and the risk factors for asthma and allergic disorders were investigated in all subjects who completed the questionnaire and underwent skin testing. Statistical analysis was carried out using logistic regression. Initially, risk factors were assessed by univariate analysis to see how each potential explanatory variable affected the probability of having allergic disease. Variables were then tested in a forward stepwise multivariate analysis. In 5687 adult subjects there was a very high (48.2%) prevalence of atopy, and 9.7% of subjects had a diagnosis of asthma. In a multivariate regression analysis sensitization to dust mite, cat, dog and mixed grasses were all independently associated with asthma. The odds ratios for current asthma increased with the increasing number of positive skin tests (any two allergens - OR 4.3, 95% CI 3.3-5.5; any three allergens - OR 7.0 95% CI 5.3-9.3; all four allergens - OR 10.4, 95% CI 7.7-14; P < 0.00001). Dog ownership (OR 1.31, 95% CI 1.10-1.57; P = 0.003) and current smoking (OR 1.36, 95% CI 1.15-1.62; P = 0.0004) were significantly and directly associated with "asthma ever". Thirteen per cent of participants reported a history of eczema. In the multivariate analysis the strongest independent associate of eczema was sensitization to dog (OR 1.37, 95% CI 1.14-1.63, P < 0.0001). Apart from dog, the strength of the association between sensitization to common allergens and eczema appeared to be much lower than in the case of asthma. The prevalence of hay fever was high (20.6%), and in the multivariate analysis the association between sensitization to pollen and hay fever was extremely strong (OR 13.6, 95% CI 11.3-16.3; P < 0.0001). The results of the current study emphasize the importance of sensitization to indoor allergens in asthma. However, evidence of a possible direct role of allergen exposure in asthma causation remains unclear.

Allergic Sensitization to Common Airborne Allergens among Adults in Estonia

“…In our study, the prevalence of allergic sensitization among subjects from 17 to 69 years was 33.0%, while the prevalence among adults aged 20–44 years was 38.5%. The prevalence seems similar to findings in Western European countries ranging from 21 to 50% [17,18,19,20,21,22]. …”

Does Exposure to Indoor Allergens Contribute to the Development of Asthma and Allergy?

“…In the Manchester Asthma and Allergy Study, sensitizations to dust mites, cats, dogs, and mixed grasses were all independently associated with asthma. The ORs for current asthma increased with the increasing number of positive skin tests [39]. In another study of children 7 or 8 years of age, sensitization to common indoor allergens, including cat, dust mite, and cockroach, was independently associated with bronchial hyperresponsiveness, with ORs ranging from 4 for cockroach to 15 for cat sensitization [40].…”

“…In a pooled analysis of more than 58,000 children, an association was found between visible mold exposure and respiratory and allergic symptoms [45]. In another study, dog ownership was significantly and directly associated with asthma development [39].…”

“…Several population-based studies have confirmed the positive association between sensitization to aeroallergens and the development of asthma and other allergic diseases [31,33,[38][39][40]. Korppi et al [33] recently showed that children who were sensitized to cat and dog had a sixfold (for cat) and ninefold (for dog) increased risk for later asthma.…”

Allergy in severe asthma

“…Numerous epidemiological studies have demonstrated that atopic sensitization is a strong risk factor for asthma in childhood (1, 2) and adulthood (3), both in the developed (3) and in the developing countries (1,2,4), supporting the notion that asthma is in part an allergic disease. However, the role of allergy in severe asthma remains the issue of considerable controversy.…”