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Bowel cancer screening cost effective, but will not reduce health inequalities

Thu, 07/20/2017 - 14:21
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The study explored the likely health gains and cost-effectiveness of a national colorectal cancer (CRC) screening programme for the indigenous Māori population of New Zealand (NZ)

Bowel-cancer screening in New Zealand will improve health cost effectively, according to University of Otago research published in the journal Cancer Epidemiology, Biomarkers and Prevention. The researchers used computer modelling to investigate health gains and found that the programme is very cost-effective for Māori and non-Māori, and for men and women. However, it will not improve ethnic inequalities in health

"We simulated the effect of a faecal occult blood screening every two years for 50-74 years old in New Zealand and found the health gains to be large," said senior author, Professor Tony Blakely from the Department of Public Health. "For example, a non-Māori male aged 60-64 will on average expect to gain about 51 days of healthy life over the remainder of their life – even allowing for nearly half of people not taking up the programme."

The paper, ‘Colorectal cancer screening: How health gains and cost-effectiveness vary by ethnic group, the impact on health inequalities, and the optimal age-range to screen’, explored the likely health gains and cost-effectiveness of a national colorectal cancer (CRC) screening programme for the indigenous Māori population of New Zealand (NZ).

Using a Markov model the researchers estimated the health benefits (QALYs), costs and cost-effectiveness of biennial immunochemical faecal occult blood testing (FOBTi) of 50-74 year olds, and measured the change in "quality-adjusted life expectancy" (QALE) as a result of the intervention.

"As a general rule of thumb, an intervention costing less than about $50,000 per quality-adjusted life-year gained is considered a 'good buy' for society – so this is a 'very good buy'," explained Professor Blakely. "While it is unfortunate it has taken New Zealand some time to implement the bowel-cancer screening programme, it is also important to both congratulate the Government for now rolling it out and communicate to the public that this is a very worthwhile screening programme to take up.”

They found that based upon a threshold of GDP per capita (NZ$45,000), CRC screening in NZ using FOBTi is cost-effective: NZ$2,930 (US$1,970) per QALY gained (95% uncertainty interval: cost saving to $6,850 (US$4,610)). Modelled health gains per capita for Māori were less than for non-Māori: half for 50-54 year olds (0·031 QALYs per person for Māori vs 0·058 for non-Māori), and a fifth (0·003 c.f. 0·016) for 70-74 year olds and ethnic inequalities in QALE increased with CRC screening.

The New Zealand programme will be for 60-74 year olds, which makes sense given limited resources like colonoscopy services and that the programme is even more cost-effective for this narrower 60-74 year age range ($1,300 per quality-adjusted life-year gained) compared to 50-74 year olds ($2,930 per quality adjusted life year gained).

"But our study demonstrates that at some time in the future, if and when service capacity permits, it would be sensible to consider lowering the entry age to 50 years old," added Professor Blakely.

Lead author, Dr Melissa McLeod added that there is a potential down-side to bowel cancer screening as bowel cancer screening achieves less health gain for Māori than non-Māori mainly because Māori have lower rates of getting bowel cancer in the first place.

"So, although bowel-cancer screening will produce improvements in health for the entire population, it will slightly widen health inequalities for Māori," she said. "It is important, therefore, to increase bowel-cancer screening rates as much as is practical for Māori to lessen the inequality impacts. However, at the same time, we also know that if we want to reduce ethnic inequalities in health, we have to implement other policies that offer bigger gains in health for Māori, such as prevention policies for tobacco control and obesity reduction. In addition, we need to focus on other screening programmes that address cancers that occur in high rates in Māori, such as cervical cancer and stomach cancer.”

“CRC screening in NZ using FOBTi is likely to be cost-effective, but risks increasing inequalities in health for Māori,” the researchers conclude. “To avoid or mitigate the generation of further health inequalities, attention should be given to underserved population groups when planning and implementing screening programmes.”