New reference values for spirometry

Thursday, 18 Aug 2016

Authors of a position statement on reference values for spirometry and their use in test interpretation hope their recommendations will encourage more clinicians to embrace the new equations which they say will better establish a patient’s normal lung function.

The three-pronged position statement is endorsed by the Australian and New Zealand Society of Respiratory Science and has been published in the Respirology journal. The recommendations include:

  1. ANZSRS recommends the adoption of the GLI (Global Lung Function Initiative) 2012 spirometry reference values throughout Australia and New Zealand.
  2. ANZSRS recommends that interpretation of spirometry results is based on the LLN from the reference values.
  3. ANZSRS encourages the use of Z-scores where possible on lung function reports.

Co-author, Associate Professor Graham Hall, Deputy Director and Head of Children’s Lung Health at Curtin University’s School of Physiotherapy and Exercise Science, said the respiratory community had been “moving slowly” to incorporate the GLI equations into their own practices.

“This position statement will accelerate this and we should see most if not all Respiratory Function Laboratory’s using the GLI equations in the near future,” he told the limbic.

“This will lead to improved patient outcomes, especially in adolescence and in patients that move between different hospitals or medical practices, for example children and young people with asthma or cystic fibrosis are transited to adult hospitals or when patients move to a new area and have their lung disease managed by a new doctor.”

He said the recommendations were a step ahead of other reference values for spirometry.

“While the current spirometry reference values work well in Caucasian patients our ability to accurately defined whether a patients lung function is within normal range if they are from other ethnic backgrounds, such as from Asia, is not that great,” he told the limbic.
“The big advantage with the Global Lung Function Initiative approach is that it provides one prediction equation that can be used in children as young as three years and in adults as old as 90 years, across four different ethnic groups – Caucasian, African-Americans and North and South East Asians.

“This is the first time we have been able to do this.”
The GLI equations are far from new, having been released in 2012. But Professor Hall said that since that time it had been demonstrated to be valid in the Australian population.

“Studies have provided evidence for the potential impact of changing to these equations and manufacturers of spirometers have incorporated the equations into their lung function system,” he said.

“In this position statement the Australian and New Zealand Society of Respiratory Science has brought all this evidence together to provide clear recommendations for health professionals measuring spirometry in their patients.”

One significant area not covered by the GLI 2012 Within the Australian and New Zealand context, the GLI 2012 equations do not include Australian Aboriginal, Torres Strait Islander, Maori and Pacific Island populations.

The authors of the position statement conceded that this remains a “significant challenge for the Australasian community”.

“For these groups, until specific GLI equations are produced, it would be reasonable to use the GLI 2012 Other equations,” they wrote.

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

They published their findings in a special Indigenous edition of the Medical Journal of Australia and lead author Tamara Blake spoke to the limbic last month.

“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 said.


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