To determine changes in prevalence of parental and childhood asthma in Merseyside between 1991 and 2006. Four standardized cross-sectional respiratory surveys using a parent-completed questionnaire were completed in 1991 (n = 1171), 1993 (n = 2368) 1998 (n = 1964) and in 2006 (n = 1074) among primary school children attending the same schools in lower socio-economic areas of Merseyside. Main outcome measures were prevalence of doctor diagnosed asthma (DDA) and the symptom triad of cough, wheeze and breathlessness (C+W+B+). Between 1991 and 1998 prevalence of DDA increased (P < 0.001), but in 2006 this decreased from 29.8 to 19.4% (P < 0.001). Prevalence of C+W+B+ increased from 7.8 to 8.0% by 1998, then decreased to 6.7% in 2006 (P = 0.39). Between 1998 and 2006, childhood hospital admissions for respiratory illness decreased from 11.3 to 9.7% (P = 0.23). During this period paternal asthma prevalence increased from 8.6 to 10.7% (P = 0.001) and maternal asthma from 11.2 to 13.4% (P = 0.09). An increase in the prevalence of DDA and asthmatic respiratory symptoms occurred in children prior to 1998, but this had decreased by 2006. Prevalence of parental asthma increased during the same period.
