The all-age spirometry reference ranges reflect contemporary Australasian spirometry

Advances in statistical modelling have allowed the creation of smoothly changing spirometry reference ranges that apply across a wide age range and better define the lower limit of normal. The objective of this study was to assess the agreement of the Stanojevic 2009 all-age reference ranges to contemporary lung function data to verify the appropriateness of this reference for clinical use in Australia and New Zealand.

Spirometry data from healthy Caucasians measured between 2000-2009 in Australia and New Zealand were collected. Z-scores were calculated for the standard spirometry outcomes based on the all-age reference ranges.

Spirometry from 2066 subjects aged 4-80 years (55% male) from 14 centres were eligible. Statistically, the collated contemporary dataset differed from the all-age reference ranges, but these differences were relatively small and clinically irrelevant representing differences of approximately 3% predicted. Significant differences were also observed between some centres and equipment, potentially indicating varying influence of equipment or subject selection.

Spirometry from contemporary Australasian healthy subjects fits the all-age reference ranges well. While the current study supports the use of the all-age reference ranges, the between-centre differences highlight the need for spirometry to be used in conjunction with other clinical findings.