The diagnosis of IBS in primary care: consensus development using nominal group technique

The criteria used to identify and diagnose irritable bowel syndrome (IBS) in primary care are unclear, even though most patients are managed entirely in this setting.

To use a validated method of consensus development [Nominal Group Technique (Rand version)] (NGT-R) in order to construct a diagnostic framework for IBS appropriate to primary care.

NGT-R is a formal method of consensus development, which uses structured interaction within a group combined with statistical derivation of group judgements. The group comprised 10 GPs with a special interest in gastroenterology and two gastroenterologists, from 10 European countries. Mailed questionnaires elicited judgements on 242 scenarios for the diagnosis of IBS, within four domains of symptoms, social and lifestyle features, psychological features and investigations. Feedback of group decisions was followed by structured face-to-face interaction and private rescoring of the questionnaire. Consensus was defined as 10/12 ratings within one of three bands, 1-3 (disagreement), 4-6 (equivocal) or 7-9 (agreement).

The defining features of IBS in primary care are alteration in bowel habit, bloating and abdominal pain, or discomfort or annoyance (the last reflecting important cultural differences in symptom description). These symptoms need to be present for at least 4 weeks. Supportive characteristics include female sex, family history of IBS, frequent clinic attendances, a recent major life event and a history of somatization behaviours. Abdominal examination was considered necessary in all patients and rectal examination, haemoglobin estimation and colonoscopy in those aged > 55 years. The subtypes of IBS are recognized, but the diagnostic process differs only in minor ways. Final consensus was reached on 46% of statements.

The basis of IBS diagnosis in primary care differs from, and is less exclusive than, existing criteria. Few features are deemed essential for diagnosis, while psychosocial features, patient characteristics and contextual factors are important in increasing diagnostic probability. There are important cultural differences in the description of key symptoms. These results provide information on the defining characteristics of IBS and the diagnostic process, as it occurs in primary care, and can guide clinical practice.