The all-age spirometry reference ranges reflect contemporary Australasian spirometry

Background and objective: 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. Methods: 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. Results: 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. Conclusions: 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.