Computed Tomography (CT) Colonography HTA Scoping Report

A proposal to undertake a Health Technology Assessment (HTA) on CT colonography was submitted by the Scottish Executive Health Department Diagnostics Collaborative. Due to the existing evidence base, and an ongoing large UK randomised controlled trial, carrying out such an HTA was not considered to be appropriate. However, given the interest in this topic it was decided to carry out a clinical and cost effectiveness review based upon existing secondary literature (HTAs, systematic reviews, evidence-based guidelines and consensus statements). This considered CT colonography as a diagnostic tool compared with colonoscopy or DCBE.

Colorectal cancer is the third most common cancer in Scotland, resulting in over 1,500 deaths and costing the country in the region of £30 million each year. The disease develops when particular types of polyps which develop in the colon and rectum, increasing in prevalence in older age, transform to become malignant. Detection and removal of these polyps reduces the risk of cancer developing or progressing.

 

A colorectal cancer screening initiative has recently been rolled out across Scotland. It is based upon the faecal occult blood test (FOBT), a cheap and practical option for population screening. However, subsequent investigation of screen detected FOBT-positive and symptomatic individuals requires a more sophisticated detection technique. Colonoscopy, in which an endoscope is used to directly examine the colon, is commonly used. This also permits biopsy of abnormalities and removal of any polyps detected. Another approach is to use imaging techniques, of which double contrast barium enema (DCBE), where the colon is filled with barium, insufflated with air, and x-rays taken, has been the accepted method. A newer alternative imaging technique of potential interest for wider use in Scotland is computed tomography (CT) colonography.

The review concluded that despite the fairly extensive body of literature on this topic, there is as yet insufficient evidence to inform recommendations on the routine use of CT colonography as a diagnostic tool in Scotland. The technique does appear to be useful as an alternative approach in particular patient groups in certain circumstances, however consideration would need to be given as to how such use would operate in practice. The manner in which services need to be organised to deliver CT colonography, in comparison to colonoscopy or DCBE is likely to be at least as significant, if not more so, as diagnostic performance, for planners making choices between the techniques.   

Evidence gathering needs to continue in a structured manner, and include long-term studies assessing the impact of CT colonography on colorectal cancer morbidity and mortality, investigation of the accuracies which can be achieved using the technique, and further assessment of patient preferences, adverse events and incidental findings. NHS QIS has no further plans to undertake work in this area but awaits the results of a large randomised controlled trial (RCT) currently in progress with interest. This is due to report in 2009 and will contribute UK clinical and cost effectiveness data to the evidence base. Survey work relating to the use of CT colonography in Scotland, and an economic evaluation based upon Scottish costs and practice could be usefully undertaken.

NHS QIS is committed to equality and diversity. This document, and the research on which it is based, have been assessed for any likely impact on the six equality groups defined by age, gender, race/ethnicity, religion/faith, disability and sexual orientation. Details of the equality and diversity impact assessment are available here.

For further information, or to receive a copy of the published report, please contact Doreen Pedlar at Doreen.Pedlar@nhs.net.