Increase in prevalence of physician-diagnosed asthma in Helsinki during the Finnish Asthma Programme: improved recognition of asthma in primary care? A cross-sectional cohort study

BACKGROUND: The continuing rise in asthma prevalence has been questioned, with recent reports suggesting a plateau. AIMS: To assess a 10-year trend in the age-adjusted prevalence of physician-diagnosed asthma, respiratory and allergic symptoms, and use of asthma medication in the adult population of Helsinki during the Finnish Asthma Programme from 1994 to 2004. METHODS: Two cross-sectional postal surveys were conducted among random Finnish National Population Registry samples 10 years apart using the same protocol. A total of 6,062 subjects (75.9%) and 2,449 subjects (61.9%) participated in 1996 and 2006, respectively. RESULTS: The prevalence of physician-diagnosed asthma increased from 6.5% in 1996 to 10.0% in 2006 (p<0.001). This was evident in both genders aged <60 years, but particularly in women aged <40 years, paralleling an increased use of asthma medication. Concurrently, the prevalence of allergic rhinoconjunctivitis increased from 37.2% to 44.4% (p<0.001). The prevalence of physician-diagnosed chronic obstructive pulmonary disease remained unchanged (3.7%), while current smoking abated. Subjects with a smoking history had more respiratory symptoms (p<0.001). Among subjects without physician-diagnosed asthma, those reporting allergic rhinoconjunctivitis had a higher prevalence of lower respiratory tract symptoms. CONCLUSIONS: The prevalence of allergic rhinoconjunctivitis and physician-diagnosed asthma has increased in Helsinki during 10 years in adults, especially in women aged <40 years. Concomitantly, the use of asthma medication increased and subjects with physiciandiagnosed asthma were less symptomatic. The increase in the prevalence of physician-diagnosed asthma may partly be due to improved diagnostic recognition of asthma in primary care during the Finnish Asthma Programme, but the concurrent rise in allergic rhinoconjunctivitis may reflect a true rise in prevalence.