Symptoms discriminate irritable bowel syndrome from organic gastrointestinal diseases and food allergy

Background The value of specific gastrointestinal symptoms in discriminatin g irritable bowel syndrome (IBS) from organic disease has been documented. In contrast, there have been few attempts to identify symptoms that discrim inate irritable bowel syndrome from food allergy, despite similarities in t heir respective symptom complexes. We aimed to investigate the value of sym ptoms in discriminating irritable bowel syndrome from organic disease and f ood allergy. Methods Subjects (n = 288) were recruited from consecutive patients present ing to the Internal Medicine, Gastroenterology and Allergy Units in Chieti. Patients completed the validated Bowel Disease Questionnaire (BDQ) prior t o an independent diagnostic evaluation, which included endoscopy when appro priate. Food allergy was diagnosed using a a-week elimination diet, followe d by a placebo-controlled food challenge test, a skin prick test and serum PAST for specific IgE for suspected foods or additives. The results of the BDQ were not considered in formulating a diagnosis. In total, 99 patients w ere diagnosed with the IBS, 79 patients were diagnosed with organic disease and 22 patients were diagnosed with food allergy. A further 88 patients wi th extraintestinal allergies were included as a control group. Results Based on logistic regression analysis, six symptom items discrimina ted IBS from organic disease, while five symptoms discriminated patients wi th IBS from control subjects. A diagnosis of IBS compared to organic diseas e was positively associated with straining on defaecation (P = 0.0001), dia rrhoea (P = 0.001) and abdominal bloating (P = 0.01), but was negatively as sociated with pain in the upper abdomen (P = 0.0004), reflux (P = 0.0001) a nd appetite loss (P = 0.004). A diagnosis of IBS compared to extraintestina l allergy was positively associated with pain relieved by bowel movement (P = 0.0001), pain in the lower abdomen (P = 0.0006), pain in both the upper and lower abdomen (P = 0.003), frequent pain (P = 0.001) and abdominal bloa ting (P = 0.0009). In comparison between IBS and food allergy patients, a d iagnosis of IBS was positively associated with pain in the lower abdomen (P = 0.001), pain relieved by bowel movements (P = 0.001), frequent pain (P = 0.02) and abdominal bloating (P = 0.03). Conclusion Symptoms appear to be useful for discriminating IBS from organic gastrointestinal disease and food allergy. (C) 2000 Lippincott Williams & Wilkins.