Post-bronchodilator spirometry reference values in adults and implications for disease management.
BACKGROUND
International guidelines promote the use of post-bronchodilator spirometry values in the definition and severity classification of chronic obstructive pulmonary disease. However, post-bronchodilator reference values have not yet been developed.


OBJECTIVE
To derive reference values for post-bronchodilator forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC, and to compare these reference values with locally derived and existing pre-bronchodilator reference values.


METHODS
Based on a random sample of a general adult population, 2,235 subjects (70% of invited subjects) performed spirometry with reversibility testing. A reference population of healthy never-smokers constituted 23% of the study population (n=515). Reference values for median and lower-limit-of-normal pre- and post-bronchodilator lung function and bronchodilator response were modeled using quantile regression analyses.


RESULTS
The reference population had equal proportions of men and women in the age range 26-82 yr. Both FEV1 and FVC decreased with age and increased with height. FEV1/FVC decreased with age, although this trend was not statistically significant for men after bronchodilatation. Linear models gave the best overall fit. Lower-limit-of-normal post-bronchodilator FEV1/FVC exceeded 0.7 for both sexes. Post-bronchodilator prediction equations gave higher predicted FEV1 and FEV1/FVC than both locally derived and existing pre-bronchodilator equations. The bronchodilator response decreased with age.


CONCLUSIONS
The present study is the first to develop reference values for post-bronchodilator lung function. Post-bronchodilator prediction equations can facilitate better management of patients with chronic obstructive pulmonary disease by avoiding falsely high FEV1% predicted with a subsequent underestimation of disease severity.
Johannessen
Ane
A
Institute of Medicine, Department of Public Health and Primary Health Care, University of Bergen, and Department of Thoracic Medicine and Centre for Clinical Research, Haukeland University Hospital, N-5021 Bergen, Norway. Ane.Johannessen@helse-bergen.no
Lehmann
Sverre
S
Omenaas
Ernst R
ER
Eide
Geir Egil
GE
Bakke
Per S
PS
Gulsvik
Amund
A
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000420:Albuterol; D001827:Body Height; D001993:Bronchodilator Agents; D015331:Cohort Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D005544:Forecasting; D005652:Functional Residual Capacity / Q000187:drug effects / Q000502:physiology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification* / Q000503:physiopathology / Q000628:therapy; D012016:Reference Values; D012737:Sex Factors; D013147:Spirometry / Q000592:standards*
D001993:Bronchodilator Agents; D000420:Albuterol