Utility of red flag symptom exclusions in the diagnosis of irritable bowel syndrome

BACKGROUND: Studies suggest that the positive predictive value of the Rome II criteria for diagnosing irritable bowel syndrome can be enhanced by excluding red flag symptoms suggestive of organic diseases. AIM: We assessed the utility of red flags for detecting organic diseases in patients diagnosed irritable bowel syndrome by their physicians. METHODS: Systematic chart reviews were completed in 1434 patients with clinical diagnoses of irritable bowel syndrome, abdominal pain, diarrhoea or constipation, who also completed questionnaires to identify Rome II criteria for irritable bowel syndrome and red flag symptoms. RESULTS: The overall incidence of gastrointestinal cancer was 2.5% (but 1.0% in those with irritable bowel syndrome), for inflammatory bowel disease 2.0% (1.2% in irritable bowel syndrome), and for malabsorption 1.3% (0.7% in irritable bowel syndrome). Red flags were reported by 84% of the sample. The positive predictive value of individual red flags for identifying organic disease was 7-9%. Excluding any patient with a red flag improved the agreement between Rome II and clinical diagnosis by a modest 5%, but left 84% of patients who were diagnosed with irritable bowel syndrome by their physicians, without a diagnosis. CONCLUSIONS: Red flags may be useful for identifying patients who require additional diagnostic evaluation, but incorporating them into the Rome criteria would not improve sensitivity and would result in too many missed irritable bowel syndrome diagnoses.