Prevalence of asthma at school age: a clinical population-based study in eastern Finland.

A questionnaire aimed at screening and identifying patients with asthmatic symptoms was sent to the parents of 2011 children aged 7 to 12 years; 1633 (81%) returned the questionnaire. A clinical examination was given to 165 symptomatic and 82 non-symptomatic children. The children were classified into three groups: 1, clinical asthma (n = 43); 2, other symptoms from lower airways (OSLA) (n = 34); 3, healthy children (n = 170). The prevalences of asthma and OSLA in the whole source population (n = 1633) were then estimated based on these figures. The lifetime prevalence of asthma was 4.0%. All children with asthma were either symptomatic or on continuous maintenance therapy during the preceding 12 months. The lifetime prevalence of OSLA was 5.0%, with 3.0% being symptomatic during the preceding 12 months. Asthma was more common in boys (5.0%) than in girls (2.8%). The respective figures for OSLA were 6.2 and 3.7%. The occurrence of asthma as well as respiratory symptoms suggestive of asthma was more common than previously observed in this area.