Spirometric criteria for airway obstruction: Use percentage of FEV1/FVC ratio below the fifth percentile, not < 70%.
BACKGROUND
Current authoritative spirometry guidelines use conflicting percentage of FEV1/FVC ratios (FEV1/FVC%) to define airway obstruction. The American Thoracic Society/European Respiratory Society Task Force characterizes obstruction as a FEV1/FVC% below the statistically defined fifth percentile of normal. However, many recent publications continue to use the Global Initiative for Chronic Obstructive Lung Disease (GOLD) primary criterion that defines obstruction as a FEV1/FVC% < 70%. Data from the Third National Health and Nutrition Examination Survey (NHANES-III) should identify and quantify differences, help resolve this conflict, and reduce inappropriate medical and public health decisions resulting from misidentification.


METHODS
Using these two guidelines, individual values of FEV1/FVC% were compared by decades in 5,906 healthy never-smoking adults and 3,497 current-smokers of black (African American), Hispanic (Latin), or white ethnicities aged 20.0 to 79.9 years.


RESULTS
In the never-smoking population, the lower limits of normal used in other reference equations fit reasonably well the NHANES-III statistically defined fifth percentile guidelines. But nearly one half of young adults with FEV1/FVC% below the NHANES-III fifth percentile of normal were misidentified as normal because their FEV1/FVC% was > 70% (abnormals misidentified as normal). Approximately one fifth of older adults with observed FEV1/FVC% above the NHANES-III fifth percentile had FEV1/FVC% ratios < 70% (normals misidentified as abnormal).


CONCLUSIONS
The GOLD guidelines misidentify nearly one half of abnormal younger adults as normal and misidentify approximately one fifth of normal older adults as abnormal.
Hansen
James E
JE
Division of Respiratory and Critical Care Physiology and Medicine, Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90509. jhansen@labiomed.org
Sun
Xing-Guo
XG
Wasserman
Karlman
K
D000328:Adult; D001741:Black or African American; D000368:Aged; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006630:Hispanic or Latino; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000175:diagnosis* / Q000208:ethnology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D012907:Smoking / Q000503:physiopathology*; D013147:Spirometry; D014481:United States; D014797:Vital Capacity / Q000502:physiology; D044465:White People