Changing prevalence of asthma in Turin school children between 1994 and 1999.

BACKGROUND: Asthma is a widespread chronic disorder in children and its prevalence has been on the increase in Europe. Only few studies have described the prevalence variation in respiratory symptoms in Italian regions. The aim of this study, conducted in Turin during the 1998/1999 school year, is to investigate the distribution of respiratory symptoms in a sample of Turin school children and to compare the obtained results with the findings of the SIDRIA study performed in 1994-95.
METHODS: The sample in study is composed of all the children attending to three elementary schools in Turin. All of the selected schools had already participated in the 94-95 ISAAC-SIDRIA study. A total of 448 pupils aged 6-10 years received a standardised questionnaire to be filled by parents.
RESULTS: Response rate is higher than 97% in all the studies. In 1999 we found that the prevalence of wheezing in the past 12 months was 7.3%. The 13.3% of children had asthma at least once in life and the 5.3% reported an attack in the last year. The comparison of our study results with the ISAAC-SIDRIA (1994-95) shows that the prevalence of asthma and asthma-like symptoms is rather stable among children, while the prevalence of bronchitis reveals a reduction of about 5.5%, but not statistically significant (p=0.094; 95%CI:-11.9;0.9). A considerable reduction in exposure to parents' passive smoke is shown: deltaP%=-4.7 (95%CI: -9.4;-0.1) for maternal smoking in pregnancy, deltaP%=-8.2 and -15.2, respectively for maternal and paternal smoking in the first two years of life.
CONCLUSIONS: The results indicate a stable prevalence rate in asthma symptoms in children. A possible explanation of slight variation in asthma prevalence may be due to a reduced exposure to outdoor and indoor risk factors as reported in the questionnaires.