Fifty six people found to have cancer between routine screenings in the first three years of the Waitemata bowel screening pilot may have been falsely reassured by a brochure called "All Clear".
The brochure was sent to those in the pilot programme who returned negative faecal immunochemical tests (Fit).
It told participants no blood had been found in their bowel motion, but this was not necessarily correct.
Blood may have been found, but too little to hit the threshold which would trigger a referral to colonoscopy.
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There were five versions of the brochure between 2011 and 2017, although only four could be found by the ministry.
A decision to withdraw the "All Clear" brochure was made at the end of February this year, around the time questions were raised on the accuracy of its contents. The message saying no blood was found did not appear in the 2017 version, but this was still implied.
The Ministry of Health refused to answer questions about whether the booklet was misleading on the grounds this was outside the scope of the Official Information Act and would have required it to form an opinion and so create new information to answer.
The ministry email trail around the withdrawal, released under the OIA, shows there was some internal concern about the accuracy of the "All Clear" title and some information in the brochure. Discussions had been held about the possibility of withdrawing it last year because it was considered it repeated information given elsewhere to participants.
Information on negative tests given to participants now still suggests no blood has been found - "because bowel cancers do not bleed all the time there is a risk that a cancer may be missed if it was not bleeding when your test was done".
The Federation of Women's Health Councils, which has raised concerns about the shortcomings in information provided to participants on negative Fit results, wants this revisited.
Co-convener Barbara Robson urged the National Screening Unit to further revise that information to explain blood may have been found in the sample, but not at a level to meet the colonoscopy follow-up threshold.
"False reassurance arising from a negative screening result can be harmful and must be minimised."
Bowel Cancer New Zealand spokeswoman Professor Sarah Derrett said the organisation had a number of concerns about the withdrawn booklet including the risk of providing false reassurance that people did not have bowel cancer.
None of the information sent to participants mentions there is a threshold for the amount of blood which would result in a positive test and referral for colonoscopy.
Ministry of Health director of service commissioning Jill Lane said "the public-facing brochures and other material were reviewed by consumers before publication, as well as being put through the health literacy review. As a result of feedback 'tiny traces of blood' is used in place of 'threshold"'.
There has also been no direct communication with people transitioning from the Waitemata pilot to the national programme to tell them that the threshold has been more than doubled, and tests are expected to pick up fewer cancers in the screened population than the old one did.
Lane said primary care providers in the Waitemata DHB area had been sent a link to the ministry's document on age range and positivity threshold.
As there was no mention of the threshold in the information to participants, the change in threshold to report a positive test was not communicated directly to pilot participants.
Lane said there was a strong correlation between the amount of blood detected in a Fit and the chance of the person having a cancer or advanced adenoma. Eighty six per cent of colonoscopies performed in the pilot where the Fit was lower than the threshold used for the national programme did not find cancers or adenomas.*
Derrett was also critical of the fact only two possible symptoms of bowel cancer were mentioned in information which goes to participants, compared with the six Bowel Cancer NZ lists.
Lane said the two symptoms listed, a change in normal pattern of going to the toilet which continued for several weeks, and blood in your bowel motion, were consistent with the possible symptoms given in the National Referral Criteria for Direct Access Colonoscopy.
BCNZ has been keen to provide consumer perspectives on how information might be interpreted, but to date has not been involved in the development of resources.
The independent assurance panel's report on its review of the national programme expressed disappointment at the limited consumer engagement in the roll-out of the programme. The panel issued three recommendations about consumer involvement including the development of a consumer engagement plan covering all levels of the programme, a reference group of consumers to give oversight and influence at the governance level and DHBs liaising regularly with relevant consumer groups over local issues and needs.
*Figures released under the Official Information Act showed in the first two-year screening round of the pilot, 33 people who returned readings between the pilot level of 75ngHb/ml and the less sensitive national programme threshold of 200ngHb/ml were found to have cancer. This was about 15.4 per cent of the total number of cancers found in that round.
Of the 29 cancers where the stage of cancer was known, eight of them were at the more serious end (stages 3 and 4) and 21 of them were stage 1 or 2, considered early stage cancers. Almost 40 per cent of the 33 cancers were found at the lower end of the readings, in the 75-99ng range.