Current GLI equations are unsuitable for TLCO in aboriginal Australians

• Published in: Respirology
• Main Authors: Brown, H., Smith, E.F., Hii, R., Headland, D., Whelan, A., Coffin, Juli, Pearson, G., Stanojevic, S., Douglas, R., Wallam, C., Atchison, C., Blundell, J., Hall, Graham L, Foong, R.E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: New Zealand; First Nations
• Online Access: https://doi.org/10.1111/resp.14215; https://researchportal.murdoch.edu.au/esploro/outputs/journalArticle/Current-GLI-equations-are-unsuitable-for/991005637964807891

Introduction/Aim: The Thoracic Society of Australia and New Zealand and Australian and New Zealand Society of Respiratory Science (ANZSRS) recommend the use of global lung initiative (GLI) reference equations for interpretation of lung function testing (LFT). However, studies assessing the suitability of the GLI2012 spirometry reference equations for Aboriginal peoples have reported mixed results. Additionally, GLI reference equations for TLCO are based only on Caucasian populations and the influence of ethnicity on these measures is unknown. This study assessed the suitability of GLI reference equations for interpretation of LFT (spirometry and TLCO) in Australian First Nations (respectfully referred to hereafter as Aboriginal) peoples. Methods: We recruited 300 people (aged 5–81 years) through engagement with local Aboriginal Medical Services and community groups. Participants completed respiratory health questionnaires, anthropometric assessment and LFT. All LFT was performed according to published guidelines and screened for acceptability and repeatability, then data were compared to GLI predicted values using age, sex, and anthropometry to calculate z-scores. For spirometry, ‘other or mixed’ ethnicity equations were selected, as per ANZSRS recommendations. Results: From questionnaire data, n = 75 (25.6%) reported history of asthma and n = 66 (22.4%) history of smoking. In total, n = 121 self-reported as never smokers with no history or symptoms of respiratory disease. Of these, we recorded spirometry in n = 101 (FEV1: n = 101, FVC: n = 84), and TLCO n = 52. Mean z-scores for spirometry were FEV1: −0.13 ± 0.94, FVC: −0.20 ± 1.12 and FEV1/FVC: −0.23 ± 0.76. Mean z-scores for TLCO were TLCO: −0.12 ± 0.78, transfer coefficient (KCO): 0.85 ± 0.81 and alveolar volume (VA): −1.15 ± 0.96. Conclusion: Proportion of participants that self-reported history of smoking is lower, and asthma is higher compared to previous reports. Data from LFT suggest the GLI2012 ‘other’ reference equations may be suitable for ...