Differences in the Spirometry Parameters Between Indigenous and Non-Indigenous Patients with COPD: A Matched Control Study

Abstract

Dorothy FL Sze,1 Timothy P Howarth,2,3 Clair D Lake,4 Helmi Ben Saad,5,6 Subash S Heraganahally1,3,7 1Department of Respiratory and Sleep Medicine, Royal Darwin Hospital, Darwin, NT, Australia; 2College of Health and Human Sciences, Charles Darwin University, Darwin, NT, Australia; 3Darwin Respiratory and Sleep Health, Darwin Private Hospital, Darwin, NT, Australia; 4Pulmonary Function Laboratory, Royal Darwin Hospital, Darwin, NT, Australia; 5Laboratory of Physiology, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia; 6Research laboratory “Heart Failure, LR12SP09”, Farhat HACHED Hospital, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia; 7College of Medicine and Public Health, Flinders University, Adelaide, SA, AustraliaCorrespondence: Subash S Heraganahally, Department of Respiratory and Sleep Medicine, Royal Darwin Hospital, Darwin, NT, Australia, Tel [phone], Fax [phone], Email [email protected]; [email protected]: Comparison of spirometry parameters between Indigenous and non-Indigenous patients with underlying chronic obstructive pulmonary disease (COPD) has been sparsely reported in the past. In this study, differences in the lung function parameters (LFPs), in particular spirometry values for forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and FEV1/FVC ratio between Indigenous and non-Indigenous patients with COPD were assessed.Methods: In this retrospective study, Indigenous and non-Indigenous patients with a diagnosis of COPD between 2012– 2020 according to spirometry criteria (ie; post-bronchodilator (BD) FEV1/FVC < 0.7) were included. A further analysis was undertaken to compare the differences in the spirometry parameters, including lower limit of normal (LLN) values matching for age, sex, height and smoking status between these two diverse ethnic populations.Results: A total of 240/742 (32%) Indigenous and 873/4579 (19%) non-Indigenous patients were identified to fit the criteria for COPD. Indigenous patients were significantly younger (mean difference 9.9 years), with a greater proportion of females (50% vs 33%), underweight (20% vs 8%) and current smokers (47% vs 32%). Prior to matching, Indigenous patients’ post-BD percent predicted values for FVC, FEV1, and FEV1/FVC ratio were 17, 17%, and − 2 points lower (Hedges G measure of effect size large (0.91), large (0.87), and small (0.25), respectively). Among the matched cohort (111 Indigenous and non-Indigenous), Indigenous patients LFPs remained significantly lower, with a mean difference of 16%, 16%, and − 4, respectively (Hedges G large (0.94), large (0.92) and small (0.41), respectively). The differences persisted despite no significant differences in LLN values for these parameters.Conclusion: Indigenous Australian patients with COPD display a significantly different demographic and clinical profile than non-Indigenous patients. LFPs were significantly lower, which may or may not equate to greater severity of disease in the absence of normative predictive lung function reference values specific to this population.Keywords: chronic obstructive pulmonary disease, Global Initiative for Chronic Obstructive Lung Disease, First Nations, Indigenous, lung function test, spirometry

Keywords

• chronic obstructive pulmonary disease
• global initiative for chronic obstructive lung disease
• first nations
• indigenous
• lung function test
• spirometry.