Different definitions of dyspepsia are applied by researchers yet measurement of the influence of these on prevalence estimates is uncertain. Despite continued debate regarding dyspepsia subgroups, few studies have used a data-drive approach to assess the existence and relevance of symptom clusters. We aimed to address both these issues. A random population sample (n = 2300) identified in New South Wales. Prevalence estimates of dyspepsia were calculated by applying four standardized dyspepsia definitions. Principal components analyses, using firstly the presence/absence of symptoms and then secondly severity of symptoms, were undertaken to determine if symptom factors existed. Prevalence estimates ranged from 11% to 36%. Similar prevalence rates for men and women were observed for all definitions except Rome II. Over one-third of respondents nominated heartburn or epigastric pain as their most bothersome symptom. However, 22% of respondents were unable to answer this question. The principal components analysis produced four symptom factors: a nausea factor, dysmotility-like dyspepsia (early satiety and fullness), ulcer-like (epigastric pain and bloating) and reflux-like (heartburn and acid regurgitation). However, the factors accounted for less than 50% of the variance. Similar factors were identified in men and women for dysmotility-like and reflux-like dyspepsia. Use of presence/absence or severity of symptoms made little difference to the symptom factors produced or the amount of variance explained. The prevalence of dyspepsia depends on the definition applied. While there is some empirical evidence of symptom subgroups, they appear to be of little clinical utility.
