Asthma and respiratory symptoms in 6-7 yr old Italian children: gender, latitude, urbanization and socioeconomic factors. SIDRIA (Italian Studies on Respiratory Disorders in Childhood and the Environment).

Little information is available on the epidemiology of childhood respiratory disorders in Southern Europe. We investigated the prevalence of asthma and respiratory symptoms in a large sample of schoolchildren, according to gender, latitude, urbanization, and socioeconomic status. Questionnaires including the International Study of Asthma and Allergies in Childhood (ISAAC) core module on wheeze, as well as questions about other respiratory symptoms (including cough and phlegm), were completed by the parents of 18,737 schoolchildren aged 6-7 yrs, from eight centres of northern and central Italy. Wheeze in the last 12 months was reported for 9% of males and 6% of females, and severe wheezing attacks for 1.4 and 0.8%, respectively. Asthma during lifetime was reported for 11% of males and 6.4% of females. The prevalence of physician-diagnosed asthma increased with level of urbanization, but reported wheezing did not, suggesting a labelling bias. Socioeconomic status was not associated with the prevalence of most wheezing symptoms or of physician-diagnosed asthma, but was negatively correlated with the number of hospital admissions because of asthma. Unlike wheezing symptoms, the prevalence of chronic cough and phlegm was associated with increasing urbanization and decreasing socioeconomic level. Urbanization and socioeconomic level have little effect on the prevalence of wheezing in this area, but they might influence the diagnosis and the management of asthma, as well as the prevalence of chronic cough and chronic phlegm.