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

Abstract

Background: Screening programs consistently underserve indigenous populations despite a higher overall burden of cancer. In this study, we explore the likely health gains and costeffectiveness of a national colorectal cancer screening program for the indigenous Maori population of New Zealand (NZ). Methods: A Markov model estimated: health benefits (qualityadjusted 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 ProgrammePilot, and NZ linked health datasets. Equity analyses substituted non-Maori values for Maori 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. Results: 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 Maori were less than for non-Maori: half for 50-To 54-year-olds (0.031 QALYs per person forMaori vs. 0.058 for non-Maori), 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. Conclusions: Colorectal cancer screening in NZ using FOBTi is likely to be cost-effective but risks increasing inequalities in health for Maori. Impact: To avoid or mitigate the generation of further health inequalities, attention should be given to underserved population groups when planning and implementing screening programs.