Which reference equation should we use for interpreting spirometry values for First Nations Australians? A cross-sectional study.

Objectives: To evaluate the suitability of the Global Lung Function Initiative (GLI)-2012 other/mixed and GLI-2022 global reference equations for evaluating the respiratory capacity of First Nations Australians.

Design, Setting: Cross-sectional study; analysis of spirometry data collected by three prospective studies in Queensland, the Northern Territory, and Western Australia between March 2015 and December 2022.

Participants: Opportunistically recruited First Nations participants in the Indigenous Respiratory Reference Values study (Queensland, Northern Territory; age, 3-25 years; 18 March 2015 - 24 November 2017), the Healthy Indigenous Lung Function Testing in Adults study (Queensland, Northern Territory; 18 years or older; 14 August 2019 - 15 December 2022) and the Many Healthy Lungs study (Western Australia; five years or older; 10 October 2018 - 7 November 2021).

Developing Fractional Exhaled Nitric Oxide Predicted and Upper Limit of Normal Values for a Disadvantaged Population.

Background: Fractional exhaled nitric oxide (Feno), used as a biomarker, is influenced by several factors including ethnicity. Normative data are essential for interpretation, and currently single cutoff values are used in children and adults.

Research Question: Accounting for factors that influence Feno, (1) what are appropriate predicted and upper limit of normal (ULN) Feno values in an underserved population (First Nations Australians), (2) how do these values compare with age-based interpretive guidelines, and (3) what factors influence Feno and what is the size of the effect?

Study Design And Methods: Feno data of First Nations Australians (age < 16 years, n = 862; age ≥ 16 years, n = 348) were obtained.