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.

Screening programs consistently underserve indigenous populations despite a higher overall burden of cancer. In this study, we explore the likely health gains and cost-effectiveness of a national colorectal cancer screening program for the indigenous Māori population of New Zealand (NZ). A Markov model estimated: health benefits (quality-adjusted life-year; QALY), costs, and cost-effectiveness of biennial immunochemical fecal occult blood testing (FOBTi) of 50- to 74-year-olds from 2011. Input parameters came from literature reviews, the NZ Bowel Screening Programme Pilot, and NZ linked health datasets. Equity analyses substituted non-Māori values for Māori values of background (noncolorectal cancer) morbidity and mortality, colorectal cancer survival and incidence, screening coverage, and stage-specific survival. We measured the change in "quality-adjusted life expectancy" (QALE) as a result of the intervention. Based upon a threshold of GDP per capita (NZ$45,000), colorectal cancer 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)]. Modeled health gains per capita for Māori were less than for non-Māori: half for 50- to 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- to 74-year-olds and ethnic inequalities in QALE increased with colorectal cancer screening. Colorectal cancer screening in NZ using FOBTi is likely to be cost-effective but risks increasing inequalities in health for Māori. To avoid or mitigate the generation of further health inequalities, attention should be given to underserved population groups when planning and implementing screening programs. .