Incidence and prevalence of multiple allergic disorders recorded in a national primary care database

Background: The co-existence of allergic conditions, food allergy, eczema, allergic rhinitis, asthma and anaphylaxis is thought to be increasing. Analysis of primary healthcare data-sets offers the possibility to advance understanding about the changing epidemiology of multiple allergic disorders. Aim: To investigate recent trends in the recorded incidence, lifetime prevalence and consulting behaviour of patients with multiple allergic disorders in England. Methods: QRESEARCH is one of the world's largest national aggregated health databases containing the records of over nine million patients (including those who have left or died). Data were extracted on all patients with a recorded diagnosis of multiple allergic disorders, and annual age-sex standardized incidence and lifetime period prevalence rates were calculated for each year from 2001 to 2005. We also analysed the consulting behaviour of these patients when compared with the rest of the QRESEARCH database population. Results: The age-sex standardized incidence of multiple allergic disorders was 4.72 per 1000 person-years in 2001 and increased by 32.9% to 6.28 per 1000 patients in 2005 (p<0.001). Lifetime age-sex standardized prevalence of a recorded diagnosis of multiple allergic disorders increased by 48.9% from 31.00 per 1000 in 2001 to 46.16 in 2005 (p<0.001). Over this period, the mean consultation rate to general practitioners for these patients increased from 4.68 to 4.90 consultations per person per year. Conclusions: Recorded incidence and lifetime prevalence of multiple allergic disorders in England have increased substantially in recent years.