Faecal immunochemical tests versus colonoscopy for post-polypectomy surveillance: an accuracy, acceptability and economic study

Atkin, W., et al | 2019|Faecal immunochemical tests versus colonoscopy for post-polypectomy surveillance: an accuracy, acceptability and economic study| Health Technology Assessment| Vol.23| 01| https://doi.org/10.3310/hta23010

 

A study which recruited male and female patients (aged between 60-72) from the Bowel Screening Programme between 30 January 2012 to 30 December 2013,  finds that annual faecal immunochemical testing, with colonoscopy in positive cases, was generally acceptable to patients and would be cost-saving compared to three-yearly colonoscopy, although it has lower sensitivity, resulting in missed lesions.

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Plain English Summary 

Bowel cancer typically develops from lesions called adenomas. Although common, most adenomas do not develop into cancer. Adenomas detected during a bowel examination, called a colonoscopy, are usually removed during this procedure. However, even after adenoma removal, some patients are still at greater risk of bowel cancer.

Depending on the number and size of adenomas found, patients are invited for a colonoscopy after 1, 3 or 5 years. Most of these additional colonoscopies will not detect cancer and they are expensive, often uncomfortable and can harm the bowel.

Both bowel cancer and adenomas can cause bleeding in the bowel. This study examined whether or not a test for blood in stool, completed at home [known as the faecal immunochemical test (FIT)], could be used instead of colonoscopy to monitor patients following adenoma removal. Colonoscopy would then be offered only to those who had a positive FIT result, indicating blood in the stool.

This study invited individuals for annual FITs for 3 years who, as part of the Bowel Cancer Screening Programme, had one or two large adenomas or three or four small adenomas removed. If a FIT detected blood in the stool at any of the tests, these individuals were immediately offered a colonoscopy. If a FIT did not detect blood in the stool at any test, these individuals were offered a colonoscopy 3 years after their adenomas were removed, as were participants who did not return their second or third FIT.

The study demonstrated that an annual FIT could identify 85 of every 100 cancers and 57 of every 100 patients with adenomas if repeated over 3 years. Annual FITs were considerably cheaper than colonoscopy after 3 years. Participants reported that the FIT was easy to use and provided reassurance. However, some were concerned that the FIT would not be as effective as colonoscopy.

Abstract

Background

In the UK, patients with one or two adenomas, of which at least one is ≥ 10 mm in size, or three or four small adenomas, are deemed to be at intermediate risk of colorectal cancer (CRC) and referred for surveillance colonoscopy 3 years post polypectomy. However, colonoscopy is costly, can cause discomfort and carries a small risk of complications.

Objectives

To determine whether or not annual faecal immunochemical tests (FITs) are effective, acceptable and cost saving compared with colonoscopy surveillance for detecting CRC and advanced adenomas (AAs).

Design

Diagnostic accuracy study with health psychology assessment and economic evaluation.

Setting

Participants were recruited from 30 January 2012 to 30 December 2013 within the Bowel Cancer Screening Programme in England.

Participants

Men and women, aged 60–72 years, deemed to be at intermediate risk of CRC following adenoma removal after a positive guaiac faecal occult blood test were invited to participate. Invitees who consented and returned an analysable FIT were included.

Intervention

We offered participants quantitative FITs at 1, 2 and 3 years post polypectomy. Participants testing positive with any FIT were referred for colonoscopy and not offered further FITs. Participants testing negative were offered colonoscopy at 3 years post polypectomy. Acceptibility of FIT was assessed using discussion groups, questionnaires and interviews.

Main outcome measures

The primary outcome was 3-year sensitivity of an annual FIT versus colonoscopy at 3 years for detecting advanced colorectal neoplasia (ACN) (CRC and/or AA). Secondary outcomes included participants’ surveillance preferences, and the incremental costs and cost-effectiveness of FIT versus colonoscopy surveillance.

Results

Of 8008 invitees, 5946 (74.3%) consented and returned a round 1 FIT. FIT uptake in rounds 2 and 3 was 97.2% and 96.9%, respectively. With a threshold of 40 µg of haemoglobin (Hb)/g faeces (hereafter referred to as µg/g), positivity was 5.8% in round 1, declining to 4.1% in round 3. Over three rounds, 69.2% (18/26) of participants with CRC, 34.3% (152/443) with AAs and 35.6% (165/463) with ACN tested positive at 40 µg/g. Sensitivity for CRC and AAs increased, whereas specificity decreased, with lower thresholds and multiple rounds. At 40 µg/g, sensitivity and specificity of the first FIT for CRC were 30.8% and 93.9%, respectively. The programme sensitivity and specificity of three rounds at 10 µg/g were 84.6% and 70.8%, respectively. Participants’ preferred surveillance strategy was 3-yearly colonoscopy plus annual FITs (57.9%), followed by annual FITs with colonoscopy in positive cases (31.5%). FIT with colonoscopy in positive cases was cheaper than 3-yearly colonoscopy (£2,633,382), varying from £485,236 (40 µg/g) to £956,602 (10 µg/g). Over 3 years, FIT surveillance could miss 291 AAs and eight CRCs using a threshold of 40 µg/g, or 189 AAs and four CRCs using a threshold of 10 µg/g.

Conclusions

Annual low-threshold FIT with colonoscopy in positive cases achieved high sensitivity for CRC and would be cost saving compared with 3-yearly colonoscopy. However, at higher thresholds, this strategy could miss 15–30% of CRCs and 40–70% of AAs. Most participants preferred annual FITs plus 3-yearly colonoscopy. Further research is needed to define a clear role for FITs in surveillance.

(Source: Health Technology Assessment (HTA)

 

The study can be read in full from HTA

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