Chest
Volume 131, Issue 2, February 2007, Pages 349-355
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Original Research
Spirometric Criteria for Airway Obstruction: Use Percentage of FEV1/FVC Ratio Below the Fifth Percentile, Not < 70%

https://doi.org/10.1378/chest.06-1349Get rights and content

Abstract

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.

Section snippets

Subjects

Subjects were 5,906 never-smoking adults without recognized respiratory or musculoskeletal disease and 3,497 current-smoking adults from the Third National Health and Nutrition Examination Survey (NHANES-III) database16from ages 20.0 to 79.9 years (third to eighth decades). Each subject selected (Table 1) was classified ethnically as black, Latin, or white, and had performed repeated spirometric maneuvers meeting ATS standards.15, 16These data from unidentified subjects had been ethically

Results

The percentage of NHANES-III never-smokers with FEV1/FVC% < 70% are shown by decade of age, sex, and ethnicity inFigure 1,top,A. For each group, the prevalence was < 5% for the third and fourth decades; thereafter, it increased to 6 to 14% for the sixth decade, 11 to 18% for the seventh decade, and 19 to 33% for the eighth decade. If ethnic- and sex-specific groups were weighted equally, mean values for the third through eighth decades, respectively, were 2.0%, 2.6%, 4.7%, 8.3%, 14.6%, and

Discussion

This study illustrates the importance of using statistically valid spirometric criteria to identify the prevalence of airway obstruction. Use of the GOLD criterion to identify obstruction as an FEV1/FVC% < 70% results in finding an inappropriately high prevalence of obstruction in adults in seventh and eighth decades, among never-smokers and probably among current-smokers. Confirmatory evidences in these decades are the relatively low specificity and very low PPV(Table 3)and high ratios of

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    Support was provided by the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center.

    There is no financial support or author involvement with organizations with financial interest in the subject matter.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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