Background: Gastroenterologists use different definitions of irritable bowel syndrome and upper dyspepsia, and the different definitions select different populations with the syndromes. The aim of the study was, in an unselected population, to find combinations of abdominal symptoms that occur together more often than can be expected by chance and thereby find statistical support for standard definitions of the syndromes.
Methods: A sex- and age-stratified random sample of 4851 Danes living in the western part of Copenhagen was interviewed about abdominal symptoms. Five years later an identical interview was carried out among the participants.
Results: The participation rate was 79% in the first study and 85% in the second. Independent of age, sex, and time, the following three definitions describe subjects with symptoms occurring together more often than could be expected by chance: 1) Subjects stating that they often experience both abdominal pain and distension and, additionally, either borborygmi or altering stool consistency. This combination occurred with a prevalence of 3.2% among men and 7.5% among women; 2) Subjects stating that they experience all of the following three symptoms: abdominal pain, heartburn, and acid regurgitation. This combination occurred with a prevalence of 1.3% among men and 0.8% among women; 3) Subjects stating that they often experience both nausea and abdominal pain. This combination occurred with a prevalence of 0.9% among men and 3.6% among women.
Conclusions: It is suggested that these three definitions should be used as standards for irritable bowel syndrome, upper dyspepsia-heart burn type and upper dyspepsia-nausea type, respectively.