Is the increase in childhood asthma coming to an end? Findings from three surveys of schoolchildren in Rome, Italy

Time trends in the prevalence of asthma, family history of asthma and atopy in Roman schoolchildren were assessed. The study population consisted of a ll children (aged 6-14 yrs) attending two primary schools in Rome, situated in urban areas that differed markedly in socioeconomic conditions and envi ronmental pollution. Three questionnaire-based surveys were conducted in 19 74, 1992 and 1998 in 2,259, 1,229 and 1,139 children. The prevalence of ast hma in males and females increased significantly during 1974-1992 and remai ned stable from 1992-1998. In age groups born in the subsequent 4-yr period s it increased almost linearly, for children born from 1962-1965 to 1982-19 85 (4.4%-12.5%), and remained remarkably stable in children born after 1985 . Because the prevalence of asthma had a steeper trend in males than In fem ales (approximately 0.55%(.)yr(-1) versits 0.25%(.)yr(-1)), the male:female asthma ratio increased (1:38 in 1974; 1:84 in 1992 and 1:62 in 1998). No s ingle environmental factor,, including area of residence, seemed to influen ce the prevalence of asthma. Family history of asthma and atopy also increa sed steadily (0.72%-respectively) more than doubling during the 24-yr study period. The strong relationship between asthma and a family history of ato py not only persisted but also strengthened over time (23.3% of asthmatic c hildren belonged to families with atopic illnesses in 1974 but 44.2% in 199 8). The environmental factors that might explain the almost three-fold rise in childhood asthma between 1974 and 1992 remain unknown but the genetic b ackground of the disease has presumably remained unchanged since the early 1970s. The fact that the prevalence of asthma increased no further during t he past 6 yrs suggests that the progressive induction of asthma symptoms in genetically predisposed subjects is a self-limiting process that has proba bly come to an end in the authors' study area.