Aims: To develop ethnic-specific echocardiography reference ranges for Aotearoa, and to investigate the impact of indexation to body surface area (BSA). Current reference international ranges are derived from people of mostly NZ European ethnicity and may not be appropriate for Māori and New Zealanders of Pacific ethnicity, who both experience high rates of cardiovascular disease.
Methods: Echocardiography was performed in a cross-sectional study of 263 healthy adults (18-50 years): Māori (N=71, 43 female), Pacific (N=53, 28 female), European (N=139, 74 female). Linear measurements of the left heart are reported and indexed to BSA. The upper/lower limit of normal (ULN/LLN) by ethnicity and sex were derived (quantile regression). Ethnic- and sex-specific differences were examined using ANOVA.
Results: The ULN was higher for all un-indexed dimensions in men compared to women, and for most indices the ULN was smallest in NZ Europeans and largest in Māori and Pacific peoples. Indexation reversed these relationships: NZ Europeans had higher ULN for many measurements.
Conclusions: Indexing to BSA introduced bias that preferences the NZ European ethnicity by creating an upper limit reference threshold that far exceeds this sample's upper range. As a result, this may lead to under-recognition of cardiac enlargement in Māori and Pacific patients, and in particular for women. Unique reference ranges for all ethnic groups and sexes are required to optimally detect and manage cardiovascular diseases (CVD) in Aotearoa.