Use of self-purchased bowel screening kits
One of the consequences of increasing awareness about bowel screening appears to be that some people are buying self-testing bowel screening kits, such as those available from pharmacies or from on-line screening services. This may lead to an expectation that asymptomatic individuals, who get a positive result from a self-purchased kit, are entitled to further investigation through the public health system. This is not the case.
We hope the following information is helpful in assisting GPs to clarify the situation regarding commercially available testing kits and manage the expectations of their patients.
In New Zealand, the use of faecal occult blood tests in asymptomatic individuals is not currently recommended nor encouraged, outside the National Bowel screening Programme. This position is endorsed by the New Zealand Society of Gastroenterology and by the National Bowel Cancer Working Group who developed the National Referral Criteria for Direct Access Outpatient Colonoscopy or CT Colonography for use by DHB staff. This recommendation also applies to the use of self-testing bowel screening kits in asymptomatic individuals
The reasons for this advice are:
screening using self-purchased kits does not include a systematic approach to the screening, diagnosis and treatment. The kits do not provide a diagnosis.
there is no structured or timely support for people who return a positive result. Most will not have cancer but maybe unduly alarmed.
there is a risk that people with symptoms may be falsely reassured by a negative test result because not all cancers will be detected by a screening test. Repeated testing as part of a structured programme reduces this possibility.
there is the potential for inequity of access to follow-on investigation for those with a positive result.
What is the difference between the self-purchased kits and Ministry supplied kits?
Positivity thresholds can vary between screening programme kits and commercial versions. However, the important difference is that when you get a test kit through the National Bowel Screening Programme, you get the whole package, including a guaranteed free, timely colonoscopy* and follow up treatment, if indicated.
* subject to eligibility for publicly funded healthcare in New Zealand.