Trends show an increase in prevalence of allergic rhinitis, eczema and other allergic conditions in children

A study from the journal ‘Thorax’ and first published online on September 1st 2006, has provided world-class-standard information on the epidemiology of allergic diseases. Researchers in the UK analysed the earliest data available on the prevalence of allergic diseases from 1971 and research over subsequent decades to include data from recent years. Both national health information sources and large national or regional surveys were examined to identify any associated trends. Striking results included a rise in the prevalence of allergic rhinitis and eczema in children and dramatic rises in hospital admissions for food allergies and anaphylaxis. This triggered hypotheses that there may have been a change in aetiological factors for these disorders.

Allergic disorders are now common in the Western world and cause significant morbidity and mortality for patients, as well as creating substantial costs for the health care system. Epidemiological studies have suggested the incidence of certain organ-confined allergic conditions may be increasing. Researchers in the UK therefore examined data on the prevalence, morbidity and mortality of allergic disorders (excluding asthma) over the last three decades. Results were first published in the journal ‘Thorax’ in 2004 but have recently become available online via the British Medical Journal. Information was drawn from a number of major published surveys and datasets on the prevalence and associated healthcare usage for a range of allergy related disorders. Studies included were conducted during the period 1971-2004 (earliest published data until present date) in various settings to provide information on estimates of symptomatic and clinician diagnosed disease prevalence, morbidity, mortality, costs of primary health care usage, prescriptions, and hospital admissions. Specific sources included the Health Survey for England (HSE), the International Study of Asthma and Allergies in Childhood (ISAAC), Morbidity Statistics from General Practice (MSGP), the Royal College of General Practitioners Weekly Returns Service (RCGP WRS), Prescribing Cost Analysis (PCA) and Hospital Episode Statistics (HES). Each study was screened for validity and definitions were matched according to WHO International Classification of Diseases (ICD) codes for each specific disease. The key allergic disorders investigated included anaphylaxis, angiooedema, food allergies, urticaria, atopic dermatitis, conjunctivitis, and allergic rhinitis. Asthma was not considered in this study as it had been separately analysed in an alternative paper. Data on children (less than 15 years), adults (15-44 years) and older adults (older than 45 years) were considered separately. Surveys were considered in a serial fashion to detect any obvious trends and variations in prevalence between children and adults. Primary results demonstrated a trebling of diagnoses of allergic rhinitis and eczema in children over the last three decades, according to symptomatic criteria. This rise was paralleled by a doubling in GP consultation rates for these disorders, followed by a recent stabilisation in their prevalence over the last decade. This is considered to be a real rise in prevalence rather than just a direct result of changes in health care or treatment of these conditions. Other significant data showed a significant rise in hospital admissions for systemic allergic conditions such as anaphylaxis (700%), food allergy (500%), urticaria (100%) and angio-oedema (40%). Although these conditions are quite rare, the rises in admissions for the former two are quite drastic, particularly in children, and rates have continued to rise in recent years. Furthermore, results also showed a rise in community prescriptions issued for all types of allergy, with those for anaphylaxis increasing more than ten-fold since 1991. This epidemiological information regarding allergic disorders in the UK is considered amongst the best in the world. However, it is still extremely limited so ongoing surveillance is required to further analyse trends. Whilst current trends have noted a rise in the prevalence of several of the allergic disorders, data it is too limited to conclude whether this is due to an actual change in the aetiology of allergic disease or population sensitivity, rather than just reflecting changes in treatment or healthcare factors. (Source: Gupta R, Sheikh A, Strachan D, Anderson R. Time trends in allergic disorders in the UK. Thorax; 000:1-6. Published Online: 1 September 2006 by BMJ Publishing Group Ltd & British Thoracic Society.)