Clinical and cost effectiveness of nurse led-structured management of diarrhoea predominant irritable bowel syndrome in primary care (Lincolnshire POACHER study); a randomised control trial

Irritable Bowel Syndrome (IBS) is common and impairs quality of life. IBS is usually diagnosed using symptom-based criteria. Treatment leads to remission in < 50%. A randomised controlled trial was conducted in primary care to evaluate whether patients meeting Rome IV criteria for diarrhoea-predominant irritable bowel syndrome (IBS), presenting to primary, care benefit from a stepwise investigative approach with treatments tailored to alternative diagnoses. Participants were randomised 1:1 to management by general practitioners encouraged to follow National Institute of Health Care Excellence IBS Guidelines (controls) or structured investigation and treatment of newly diagnosed conditions (intervention). The primary end point was IBS Symptom Severity Score (IBSSSS) change. Between October 2020- September 2023, 113 participants 81 female, mean age 36 years, 62 (70%) with severe symptoms, from 44 Lincolnshire practices were randomised, of whom 81 completed follow-up (28% attrition). Study arms were balanced. Mean IBSSSS (SD) decreased from 303.00 (92.85) to 234.05 (114.20) in the control arm and from 312.00 (72.59) to 126.49 (85.26) in the intervention arm. The absolute adjusted between-group mean difference was − 112.29 points (95% CI-151.68 to -72.91; p < 0.0001], corresponding to a large standardised effect size (Hedges’ g = 0.95). Improved quality of life (p < 0.001) and anxiety (p = 0.04) also favoured intervention. In 74% (n=32/43) of intervention participants completing the study, appropriate treatment of alternative diagnoses was reported to lead to sustained clinical improvement. Diagnoses included bile acid diarrhoea (n=18, 42%), small intestinal bacterial overgrowth (n=13, 30%), fructose intolerance (n=8, 19%), exocrine pancreatic insufficiency (n=3, 7%), lactose intolerance (n=2, 5%) and coeliac disease (n=1, 2%) with more than one condition in 12 participants (28%). Advice on lifestyle (n=13, 30%) and toileting (n=15, 35%) provided additional sustained benefit. Mean intervention costs were £1396 compared to £315 for controls. The number of appointments did not correlate with final IBSSSS (p=0.21). Despite significant findings, under-recruitment, higher-than-anticipated loss to follow-up and lack of blinding may overestimate the benefits found (prospective trial registration: 14th July 2020, ISRCTN87945798). What is already known on this topic. Irritable Bowel Syndrome (IBS) is the most common gastrointestinal condition seen by primary care. IBS characterised by diarrhoea (IBS-D), when treated following NICE guidelines recommended for Primary Care, has a remission rate <50% at 7 years. NICE guidelines advocate a positive diagnosis should be made if there are no red flag symptoms, typical symptoms and specified blood tests are normal. However, other data suggest that accurate diagnosis of disorders mimicking IBS-D require a different approach. No randomised studies have previously investigated the benefit from a more detailed testing strategy in this patient group presenting to primary care. What this study adds This trial suggests that there may be clinical benefit from lifestyle assessment combined with a structured investigative approach, compared to normal care. Appropriate investigations and treatment can be delivered by trained nurses. Currently, NICE guidelines in this patient group are frequently disregarded by GPs. How this study might affect research, practice or policy NICE Guidance to GPs does not reflect the approach advocated by the British Society of Gastroenterology when these patients present to secondary care. More research is needed to assess which investigations are valuable, the best sequence of investigations, and how these can be introduced in primary care.