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.
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
Ane
A
Johannessen
Sverre
S
Lehmann
Ernst R
ER
Omenaas
Geir Egil
GE
Eide
Per S
PS
Bakke
Amund
A
Gulsvik
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