Mixture model analysis identifies irritable bowel syndrome subgroups characterised by specific profiles of gastrointestinal, extraintestinal somatic and psychological symptoms

Summary Background Current subgrouping of Irritable Bowel Syndrome (IBS) is exclusively based on stool consistency without considering other relevant gastrointestinal (GI), extraintestinal somatic or psychological features. Aim To identify subgroups based on a comprehensive set of IBS‐related parameters. Methods Mixture model analysis was used, with the following input variables: 13 single‐item scores from the IBS‐specific Gastrointestinal Symptom Rating Scale, average stool consistency and frequency from a 7‐day Bristol Stool Form diary, 12 single‐item extraintestinal symptom scores from the Patient Health Questionnaire‐12, and anxiety and depression subscale scores from the Hospital Anxiety and Depression scale. The resulting latent subgroups were compared regarding symptom profiles using analysis of variance followed by pair‐wise comparisons. Results One hundred and seventy‐two IBS patients (Rome III; 69% female; mean age 33.7 [range 18‐60] years) were included. The optimal subgrouping showed six latent groups, characterised by: (I) constipation with low comorbidities, (II) constipation with high comorbidities, (III) diarrhoea with low comorbidities, (IV) diarrhoea and pain with high comorbidities, (V) mixed GI symptoms with high comorbidities, (VI) a mix of symptoms with overall mild severity. The subgroups showed differences in the distribution of Rome III‐subtypes, IBS severity, presence of anxiety and depression, and gender, but not regarding age, IBS duration or reported post‐infectious onset of IBS. Conclusions This model‐based subgrouping of IBS partly supports the distinction of subgroups based on bowel habits, but additionally distinguishes subgroups with or without co‐morbid extraintestinal somatic and psychological symptoms. The resulting groups show specific profiles of symptom combinations.