Abstract
How we count Māori, Indigenous peoples of Aotearoa New Zealand (NZ) and adjust for age structure has equity implications for epidemiological research. Using two Māori population estimates, the Estimated Resident Population (ERP) from the corrected 2018 Census and Health Service User (HSU) Population, we make a single-year comparison of enteric infections hospitalization rates for Māori. The ERP was used to compare age-standardized rates derived using the age-distributions of Total Māori, Prioritized NZ European, and the World Health Organization (WHO) Standard Populations. In 2018, the crude hospitalization rate for Māori increased from 500 (ERP) to 541 (HSU) per 100,000. Crude rate ratios (RR) for Māori compared to NZ European differed from 0.9 (ERP) to 1.1 (HSU), though this shift was disease-specific e.g. salmonellosis RR changed from 0.7 (ERP) to 0.8 (HSU); and when considering standard population from 0.7 (Māori standard), 1.0 (NZ European standard) and 0.7 (WHO standard). Using ERP rather than HSU may systematically understate the Māori-NZ European RR, with direct implications for resource allocation and service planning. However, HSU is available from 2015, and its composition changed over time, which may present challenges when consistent measures are needed over longer time periods.