Prevalence of asthma, aspirin intolerance, nasal polyposis and chronic obstructive pulmonary disease in a population-based study

Background Remarkable overlap exists in symptoms between asthma and chronic obstructive pulmonary disease (COPD), and the symptoms of the patients wit h mild asthma are often falsely thought to be caused by smoking. The object ive of the study was to determine the prevalence of doctor-diagnosed asthma , asthmatic symptoms and doctor-diagnosed COPD in an adult population. The prevalence and relation to asthma of aspirin intolerance, nasal polyposis, allergic rhinitis and smoking habits were also examined. Methods Postal questionnaire survey of a population-based random sample (43 00) of adult women and men aged 18-65 years served by the Paijat-Hame Centr al Hospital in southern Finland (a region with 208 000 inhabitants) was per formed. Results The non-response-adjusted prevalence (Drane's linear method) of doc tor-diagnosed asthma was 4.4% (95% CI: 3.3-5.5%) and of COPD 3.7% (95% CI: 2.7-4.8%). The prevalence of allergic rhinitis was 37.3% (95% CI:33.3-41.2% ), and of overall aspirin intolerance 5.7% (95% CI:4.4-7.1%). The observed prevalence of aspirin intolerance causing shortness of breath or attacks of asthma was 1.2% and it was higher in patients with doctor-diagnosed asthma than without (8.8% versus 0.8%, relative risk [RR] = 11.4, P < 0.0001), an d higher in those with allergic-like rhinitis than without (2.6% versus 0.3 %, RR = 7.7, P < 0.0001). The prevalence of nasal polyposis was 4.3% (95% C I:2.8-5.8%). Conclusions The current prevalence of doctor-diagnosed asthma among adults is 4.4%, and allergic rhinitis, nasal polyposis and aspirin intolerance are associated with an increased risk of asthma. There is also association bet ween aspirin-induced asthma and allergic-like rhinitis.