FEV1/FEV6 and FEV6 as an alternative for FEV1/FVC and FVC in the spirometric detection of airway obstruction and restriction |
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Authors: | Vandevoorde Jan Verbanck Sylvia Schuermans Daniel Kartounian Jan Vincken Walter |
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Affiliation: | Department of General Practice, Dutch-Speaking University of Brussels (Vrije Universiteit Brussel), Brussels, Belgium. Jan.Vandevoorde@vub.ac.be |
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Abstract: | STUDY OBJECTIVES: To evaluate the use of the FEV(1)/forced expiratory volume at 6 s of exhalation (FEV(6)) ratio and FEV(6) as an alternative for FEV(1)/FVC and FVC in the detection of airway obstruction and lung restriction, respectively. SETTING: Pulmonary function laboratory of the Academic Hospital of the Free University of Brussels. PARTICIPANTS: A total of 11,676 spirometric examinations were analyzed on subjects with the following characteristics: white race; 20 to 80 years of age; 7,010 men and 4,666 women; and able to exhale for at least 6 s. METHODS: Published reference equations were used to determine lower limits of normal (LLN) for FEV(6), FVC, FEV(1)/FEV(6), and FEV(1)/FVC. We considered a subject to have obstruction if FEV(1)/FVC was below its LLN. A restrictive spirometric pattern was defined as FVC below its LLN, in the absence of obstruction. From these data, sensitivity and specificity of FEV(1)/FEV(6) and FEV(6) were calculated. RESULTS: For the spirometric diagnosis of airway obstruction, FEV(1)/FEV(6) sensitivity was 94.0% and specificity was 93.1%; the positive predictive value (PPV) and negative predictive value (NPV) were 89.8% and 96.0%, respectively. The prevalence of obstruction in the entire study population was 39.5%. For the spirometric detection of a restrictive pattern, FEV(6) sensitivity was 83.2% and specificity was 99.6%; the PPVs and NPVs were 97.4% and 96.9%, respectively. The prevalence of a restrictive pattern was 15.7%. Similar results were obtained for male and female subjects. When diagnostic interpretation differed between the two indexes, measured values were close to the LLN. CONCLUSIONS: The FEV(1)/FEV(6) ratio can be used as a valid alternative for FEV(1)/FVC in the diagnosis of airway obstruction, especially for screening purposes in high-risk populations for COPD in primary care. In addition, FEV(6) is an acceptable surrogate for FVC in the detection of a spirometric restrictive pattern. Using FEV(6) instead of FVC has the advantage that the end of a spirometric examination is more explicitly defined and is easier to achieve. |
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Keywords: | COPD forced expiratory volume forced expiratory volume at 6 s of exhalation pulmonary function testing spirometry FEV6" },{" #name" :" keyword" ," $" :{" id" :" cekeyw70" }," $$" :[{" #name" :" text" ," _" :" forced expiratory volume at 6 s of exhalation FET" },{" #name" :" keyword" ," $" :{" id" :" cekeyw90" }," $$" :[{" #name" :" text" ," _" :" forced expiratory time LLN" },{" #name" :" keyword" ," $" :{" id" :" cekeyw110" }," $$" :[{" #name" :" text" ," _" :" lower limits of normal NHANES III" },{" #name" :" keyword" ," $" :{" id" :" cekeyw130" }," $$" :[{" #name" :" text" ," _" :" third National Health and Nutrition Examination Survey NPV" },{" #name" :" keyword" ," $" :{" id" :" cekeyw150" }," $$" :[{" #name" :" text" ," _" :" negative predictive value PPV" },{" #name" :" keyword" ," $" :{" id" :" cekeyw170" }," $$" :[{" #name" :" text" ," _" :" positive predictive value |
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