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FEV1/FEV6 for Detection of Airflow Obstruction: Better Forget It FREE TO VIEW

Carlos A. C. Pereira, PhD
Author and Funding Information

Affiliations: Dr. Pereira is affiliated with the Paulista School of Medicine.

Correspondence to: Carlos A. C. Pereira, Paulista School of Medicine, Av Iraí, 393, conj 34, São Paulo 04082-001, Brazil; e-mail: pereirac@uol.com.br


Financial/nonfinancial disclosures: The author has reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

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


© 2009 American College of Chest Physicians


Chest. 2009;136(6):1701. doi:10.1378/chest.09-1232
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To the Editor:

The FEV1/forced expiratory volume in 6 s (FEV6) ratio has been proposed for diagnosis of airflow obstruction (AO). A recent metaanalysis1 concluded that FEV1/FEV6 ratio is a valid alternative to the FEV1/FVC ratio. This conclusion is questionable. In 5 of the 11 studies included in the metaanalysis, the standard for the diagnosis of AO was an FEV1/FVC ratio of <70%. This fixed value decreases the sensitivity of the FEV1/FVC ratio.

Since FEV6 cannot be greater than FVC, one can anticipate that the number of false-positive values for the FEV1/FEV6 ratio should be zero. In one study included in the metaanalysis (reference 28),1 this value reached 30% of total sample.

Reduced end-expiratory flows and prolonged expiratory times, which commonly exceed 6 s, occur in the initial stage of AO. The FEV1/FEV6 ratio can therefore lose sensitivity in early diagnoses, especially in aging patients, in whom the time required to complete the FVC maneuver increases.2 In two studies (references 22 and 25) included in the study by Hansen et al,2 it was possible to calculate the sensitivity of the FEV1/FEV6 ratio in patients with mild AO. The values decreased to 73% and 82%, respectively. In a recent study,3 we compared the sensitivity of FEV1/FVC ratio and FEV1/FEV6 ratio in patients with mild AO. The sensitivity for the FEV1/FEV6 ratio was only 75%. The exclusion of unpublished studies can introduce bias. In one such study (reference 10 in Soares et al3), 1,926 spirometry tests were evaluated. The sensitivity was for the FEV1/FEV6 ratio was 85.6%, but this value decreased to 74% among patients with mild obstruction.

In conclusion, substituting FEV6 for FVC to determine AO reduces the sensitivity of spirometry findings, especially in older individuals and in those persons with mild AO.

Jing JY, Huang TC, Cui W, et al. Should FEV1/FEV6replace FEV1/FVC ratio to detect airway obstruction? A metaanalysis. Chest. 2009;135:991-998. [PubMed] [CrossRef]
 
Hansen JE, Sun XG, Wasserman K. Should forced expiratory volume in six seconds replace forced vital capacity to detect airway obstruction? Eur Respir J. 2006;27:1244-1250. [PubMed]
 
Soares AL, Rodrigues SC, Pereira CA. Airflow limitation in Brazilian Caucasians: FEV1/FEV6vs. FEV1/FVC. J Bras Pneumol. 2008;34:468-472. [PubMed]
 

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References

Jing JY, Huang TC, Cui W, et al. Should FEV1/FEV6replace FEV1/FVC ratio to detect airway obstruction? A metaanalysis. Chest. 2009;135:991-998. [PubMed] [CrossRef]
 
Hansen JE, Sun XG, Wasserman K. Should forced expiratory volume in six seconds replace forced vital capacity to detect airway obstruction? Eur Respir J. 2006;27:1244-1250. [PubMed]
 
Soares AL, Rodrigues SC, Pereira CA. Airflow limitation in Brazilian Caucasians: FEV1/FEV6vs. FEV1/FVC. J Bras Pneumol. 2008;34:468-472. [PubMed]
 
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