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

Background
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%.

Methods
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.

Results
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).

Conclusions
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).