Prevalence of asthma and asthma symptoms in a general population sample of north Italy.

The prevalence rates of asthma and asthma symptoms were investigated in a general population sample (n = 3,289) living in a rural area of northern Italy. The subjects received a standard questionnaire and performed lung function tests with automated equipment. The overall prevalence rate of reported diagnosis of asthma was 5%. In young nonsmokers of both sexes the prevalence rates of reported diagnoses were higher than those of symptoms whilst the reverse occurred in older age groups. The prevalence rates decreased from childhood to young adults and increased again in older age groups. In smokers, reported diagnoses and symptoms increased with age and the prevalence rates of symptoms were always higher than those of diagnoses. Smokers with symptoms and reported diagnoses had lower lung function parameters than those with only symptoms. The distribution of asthma symptoms in our population indicates the importance of cigarette smoke and other environmental factors in the expression of the disease.