Systematic review: the epidemiology of eosinophilic oesophagitis in adults. 
The epidemiology of eosinophilic oesophagitis (EoE) in adults remains unclear.  To estimate the prevalence and incidence of EoE through a systematic review of published literature.  We conducted systematic literature searches in PubMed in September 2009.  Studies were excluded if they contained any participants below 18 years of age, published in languages other than English, or had no exact reporting of prevalence or incidence rates.  Nine studies fulfilled the criteria; one evaluated a population-based sample, one examined patients referred from a defined geographical region and seven studies examined the prevalence in a total of 6018 patients in clinic or hospital settings.  The lowest prevalence was reported in population-based studies (4 and 0.23 per 1000), followed by studies of unselected patients (1.0%, 6.5%) and highest in the other five clinic/hospital based studies (2.2-48.2%).  Men were more affected in seven of eight studies (64.5-100%).  The sample size weighted average prevalence from the population-based studies was 0.03%.  For studies evaluating symptomatic patients, it was 2.8%.  The prevalence of EoE in adults varies considerably based on the study sampling frame: high in dysphagia patients, quite low in population-based studies and intermediate among unselected endoscopy patients.