Comparison of diffusing capacity of carbon monoxide (DLCO) and total lung capacity (TLC) between Indigenous Australians and Australian Caucasian adults

Timothy Howarth; Helmi Ben Saad; Ara J Perez; Charmain B Atos; Elisha White; Subash S Heraganahally

doi:10.1371/journal.pone.0248900

Comparison of diffusing capacity of carbon monoxide (DLCO) and total lung capacity (TLC) between Indigenous Australians and Australian Caucasian adults

PLoS One. 2021 Apr 2;16(4):e0248900. doi: 10.1371/journal.pone.0248900. eCollection 2021.

Authors

Timothy Howarth^{1

2}, Helmi Ben Saad^{3

4

5}, Ara J Perez², Charmain B Atos², Elisha White⁶, Subash S Heraganahally^{2

6

7}

Affiliations

¹ College of Health and Human Sciences, Charles Darwin University, Darwin, Northern Territory, Australia.
² Darwin Respiratory and Sleep Health, Darwin Private Hospital, Darwin, Northern Territory, Australia.
³ Université de Sousse, Faculté de Médecine de Sousse, Laboratoire de Physiologie, Sousse, Tunisia.
⁴ Department of Physiology and Functional Exploration, Farhat HACHED Hospital, Sousse, Tunisia.
⁵ Heart Failure Research Laboratory (LR12SP09), Farhat HACHED Hospital, Sousse, Tunisia.
⁶ Department of Respiratory and Sleep Medicine, Royal Darwin Hospital, Darwin, Northern Territory, Australia.
⁷ College of Medicine and Public Health and Northern Territory Medical Programme, Flinders University, Adelaide, South Australia, Australia.

Abstract

Background and objective: Currently there is paucity of evidence in the literature in relation to normative values for diffusing capacity of carbon monoxide (DLCO) and total lung capacity (TLC) among Indigenous Australians. Hence, in this study we assessed the DLCO and TLC parameters among Indigenous Australians in comparison to Australian Caucasian counterparts.

Methods: DLCO and TLC values were assessed and compared between Indigenous Australians and Australian Caucasians matched for age, sex and body mass index, with normal chest radiology.

Results: Of the 1350 and 5634 pulmonary function tests assessed in Indigenous Australian and Australian Caucasian adults respectively, a total of 129 Indigenous Australians and 197 Australian Caucasians met the inclusion criteria. Absolute DLCO and TLC values for Indigenous Australians were a mean 4.3 ml/min/mmHg (95% CI 2.86, 5.74) and 1.03 L (95% CI 0.78, 1.27) lower than Australian Caucasians (p<0.01). Percentage predicted values were 15.38 (95% CI 11.59, 19.17) and 16.63 (95% CI 13.59, 19.68) points lower for DLCO and TLC, respectively. Lower limit of normal (LLN) values did not significantly differ between groups, however a significantly greater proportion of Indigenous Australians recorded values below the LLN in comparison to Australian Caucasians for DLCO (64 vs. 25%, p<0.01) and TLC (66 vs. 21%, p<0.01). Significant differences for the interaction of sex on DLCO and TLC were noted in Australian Caucasians, with reduced or absent sex differentiation among Indigenous Australians.

Conclusions: There are significant differences in DLCO and TLC parameters between Indigenous Australian compared to Australian Caucasians. Appropriate DLCO and TLC norms need to be established for Indigenous Australians.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adolescent
Adult
Australia
Female
Humans
Indigenous Peoples
Lung / physiology*
Male
Middle Aged
Pulmonary Diffusing Capacity*
Total Lung Capacity*
White People
Young Adult

Grants and funding

SSH as director of Darwin Respiratory and Sleep Health received a voluntary donation from Boehringer Ingelheim (https://www.boehringer-ingelheim.com.au/) which as such did not attract any grant number. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.