Call for Indigenous-specific spirometry reference guidelines

Public health

8 Jul 2016

Researchers have identified an “urgent” need for the development of spirometry reference values specifically for Indigenous Australians.

Existing literature reports lower spirometry values (15-30% lower) in Indigenous Australians compared with people of European ancestry, while there are no studies that have involved Torres Strait Islander participants.

However researchers who conducted the systematic review of published spirometry data for Australian Aboriginal and Torres Strait Islander (Indigenous) peoples, believe the lower values may be due to study limitations.

They have published their findings in a special Indigenous edition of the Medical Journal of Australia.

Lead author Tamara Blake, a respiratory scientist at the Centre for Children’s Health Research at the Queensland University of Technology, and the Indigenous Respiratory Outreach Care Program at Brisbane’s Prince Charles Hospital, said the results demonstrated the need for more research.

“We just don’t know whether the values will be that different, but given the burden of respiratory disease in Indigenous Australians across all ages, it makes sense to find out,” she told the limbic.

In May 2012 the Global Lung Function Initiative (GLI) Task Force published multi-ethnic reference values for spirometry that included validated spirometry reference values for people of European ancestry and three other ethnic groups. African American and South-East Asian groups were found to have FEV1 and FVC values 10–16% lower than in people of European ancestry of matching sex, height and age, whereas values in North-East Asians were only 1–4% lower.

“Use of the correct reference values is important, as comparison against incorrect reference values could misclassify a person as having normal or abnormal lung function, and thus lead to possible misdiagnosis and either deprivation of necessary interventions or unwarranted overtreatment,” the authors wrote.

“Given the high burden of respiratory disease in Indigenous Australians, the variations in ethnic adjustment factors and the implications for clinical care and outcomes, it is important to know how spirometry values in the Indigenous Australian population compare with those among people of European ancestry. This will inform what reference values or adjustment factors should be used.”

Ms Blake said that while the systematic review of the literature found lower lung function values in Indigenous Australians compared with people of European ancestry, there were limitations in all of the studies.

None of them provided a “reliable set of Aboriginal or Torres Strait Islander spirometry reference values that could be validated against ATS-ERS (American Thoracic Society and European Respiratory Society) criteria.”

“It therefore remains inconclusive as to what spirometry reference values should be used when testing Indigenous Australians,” the authors concluded.

“Given the importance of spirometry testing on respiratory diagnosis and treatment, there is an urgent need for accurate and validated reference values for Indigenous Australians.

Ms Blake is well into recruitment for the next stage of her research, which she hopes will result in enough data to meet the requirements for GLI-endorsed guidelines.

In the meantime, she said health care professionals should be aware of the limitations of using an ethnic correction or adjustment factor when managing Indigenous patients.

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