Incidence, prevalence, and trends of general practitioner-recorded diagnosis of peanut allergy in England, 2001 to 2005.

BackgroundPrevious descriptions of the epidemiology of peanut allergy have mainly been derived from small cross-sectional studies.ObjectiveTo interrogate a large national research database to provide estimates for the incidence, prevalence, and trends of general practitioner (GP)-recorded diagnosis of peanut allergy in the English population.MethodsVersion 10 of the QRESEARCH database was used with data from 2,958,366 patients who were registered with 422 United Kingdom general practices in the years 2001 to 2005. The primary outcome was a recording of clinician-diagnosed peanut allergy.ResultsThe age-sex standardized incidence rate of peanut allergy in 2005 was 0.08 per 1000 person-years (95% CI, 0.07-0.08), and the prevalence rate was 0.51 per 1000 patients (95% CI, 0.49-0.54). This translated into an estimated 4000 incident cases (95% CI, 3500-4600) and 25,700 prevalent cases (95% CI, 24,400-27,100) of GP-recorded diagnosis of peanut allergy in England in 2005. During the study period, the incidence rate of peanut allergy remained fairly stable, whereas the prevalence rate doubled. In those under 18 years of age, the crude lifetime prevalence rate was higher in males than females. A significant inverse relationship between prevalence and socioeconomic status was found.ConclusionThese data on GP-recorded diagnosis of peanut allergy from a large general practice database suggest a much lower prevalence in peanut allergy than has hitherto been found. This difference may in part be explained by underrecording of peanut allergy in general practice. Further research is needed to assess the true frequency of peanut allergy in the population and whether there has been a true increase in recent years.