WASh multicentre randomised controlled trial: water-assisted sigmoidoscopy in English NHS bowel scope screening

Organisation/institution: Centre for Health Economics & Medicines Evaluation (CHEME) at Bangor University, University Hospital of North Tees, North Wales Organisation for Randomised Trials in Health (NWORTH)

Key contact: Dr Llinos Haf Spencer, CHEME, Bangor University, l.spencer@bangor.ac.uk

What was the question that we could help with?

This WASh study aimed to investigate patients’ preferences for bowel screening, using the flexible sigmoidoscopy (FS) procedure to look for the presence of colorectal cancer.

What did we do?

Health and Care Economics Cymru researchers conducted a discrete choice experiment (DCE) to explore the relative importance of different aspects of FS to patients. Procedural pain was described in terms of three possible levels, whilst all other attributes (missing an abnormality, procedure time, bowel cleansing, and complication) were described using two levels. The DCE used an experimental design catalogue which resulted in eight hypothetical binary choices that were presented to patients in the WASh RCT, 24 hours after their FS procedure. Patients were asked to choose (or make trade-offs) between the attributes in the DCE tasks by comparing the variation of levels of attributes between pairwise choices and then choosing between the two or more competing hypothetical scenarios, thus revealing their relative preference for different attributes.

What is the expected impact?

This WASh patient preference DCE showed that information about pain and potential effectiveness of FS should be given to patients before they make a choice regarding FS options. Patients also preferred shorter time procedures over a longer time period and patients would be willing to endure more pain for less false negative results.


Rutter, M. D., Evans, R., Hoare, Z., Von Wagner, C., Deane, J., Emaily, S., Larkin, T., Edwards, R., Yeo, S. T., Spencer, L. H., Holmes, E., Saunders, B. P., Rees, C. J., Tsiamoulos, P., BEintaris, I. On behalf of the WASh trial team. (2020). The WASh multicentre randomised controlled trial: Water-assisted sigmoidoscopy in English NHS bowel scope screening. Gut. doi: 10.1136/gutjnl-2020-321918