[Time trends and geographical variations in the prevalence of symptoms of allergic rhinitis in 6-7-year-old children from eight areas of Spain according to the ISAAC]

Background:Phase III of the International Study of Asthma and other Allergies in Childhood (ISAAC) was carried out in schoolchildren aged 6-7 years from eight areas of Spain to estimate time trends and geographic variations in the prevalence of symptoms of allergic rhinitis (AR).

Material and method:A standard and validated questionnaire was used following ISAAC methodology and was completed by the schoolchildren's parents. The prevalence of symptoms of AR in Phase I (1993-1994) and Phase III (2001-2002) was compared. Eight centers participated: Asturias, Barcelona, Bilbao, Cartagena, Castellón, Madrid, Pamplona and Valencia. Poisson regression was used in the analysis.

Results:A total of 25,113 schoolchildren were studied with a median participation of 81.7 %. In all centers, AR symptoms tended to increase, with a prevalence ratio of rhinoconjunctivitis in the previous year of 1.61 (95 % confidence interval: 1.48-1.76) when both phases, adjusted by gender, center, and seasonal variation, were compared. The prevalence of AR symptoms was higher in boys than in girls. Wide variations in the prevalence of AR were observed across centers with a higher prevalence in Asturias, Madrid, Cartagena and Bilbao. Lower prevalences were reported in Barcelona, Castellón and Pamplona.

Conclusions:There seems to have been a general increase in AR symptoms. Substantial variations between centers suggested that there may be local differences in risk factors. Intense research will be required for satisfactory preventive actions.