Introduction Our group has previously described investigational pathways that occur in patients with diarrhoea predominant irritable bowel syndrome (IBS-D). Currently, there is a paucity of work undertaken in either primary or secondary evaluating patients with constipation predominant irritable bowel syndrome (IBS-C).This study evaluates the population prevalence of IBS-C, determining also the investigational pathways that occur in these patients.

Methods We prospectively collected data from 3 groups of patients between April 2005 and November 2012. Group 1 (n = 1002) were healthy volunteers, Group 2 (n = 64) were patients fulfilling Rome III criteria for IBS-C, with Group 3 (n = 403) being patients fulfilling Rome III criteria for IBS-D. In Group 1 the prevalence of IBS and its differing subtypes (IBS-D, IBS-C, mixed IBS (IBS-M) and unspecified IBS) were determined using the Rome III Diagnostic Questionnaire. In groups 2 and 3, demographic data and diagnostic yield of any investigations undertaken as part of the diagnostic workup were evaluated. Statistical analysis was performed using SPSS version 17.0 (SPSS Inc, Chicago, IL) with Fisher’s exact test used to compare categorical data, and an unpaired T-test used to compare continuous data

Results IBS prevalence in healthy volunteers (Group 1) was 6% (60/1002), with 80% being female (p < 0.0001).Mixed IBS was the most common IBS subtype (Table 1), with IBS-C patients being significantly older than other patients with IBS (mean age 45 vs 30 years, p = 0.027). When comparing Groups 2 and 3, patients with IBS-C underwent a total of 56 additional investigations (including radiological, endoscopic investigations, breath tests, SeHCAT scan, faecal pancreatic elastase), significantly lower than the number of investigations undertaken in the IBS-D group of 885 (p < 0.001). Whilst further investigations in Group 3 identified an alternative diagnosis to IBS-D in 25%, the 56 additional tests undertaken in Group 2 did not help establish an alternative diagnosis to IBS-C in any of the patients.

Conclusion This is the first study to evaluate the population prevalence of differing IBS subtypes within a UK population. Whilst, further investigation of IBS-D patients may lead to an alternative diagnoses and instigation of an appropriate management strategy, the merits of further investigation in IBS-C patients is to be questioned.

Disclosure of Interest None Declared