Use of FEV1/FEV6 Ratio May Lead to Underdiagnosis of COPD in Women

Spirometry test
Spirometry test
There is significant disparity in the ratios for postbronchodilator FEV1/FEV6 and FEV1/FVC %, and this disparity is very pronounced in women.

This article is part of Pulmonology Advisor‘s coverage of the CHEST 2019 meeting, taking place in New Orleans, LA. Our staff will report on medical research related to asthma, COPD, critical care medicine, and more conducted by experts in the field. Check back regularly for more news from CHEST 2019.

NEW ORLEANS — There is significant disparity in the ratios for postbronchodilator forced expiratory volume in 1 second (FEV1)/FEV6 and FEV1/forced vital capacity (FVC) %, and this disparity is very pronounced in women, without any differences in age, body mass index, total lung capacity (TLC) or carbon monoxide diffusing capacity (DLCO) to account for the disparity, according to research results presented at the CHEST Annual Meeting, held October 19 to23, 2019, in New Orleans, Louisiana.

Because many patients find FVC a difficult maneuver, FEV6 has been proposed as an alternative way of diagnosing chronic obstructive pulmonary disease (COPD). The current study examined the influence of gender in a real-world community-based setting on the discrepancy between FEV1/FEV6 and FEV1/FVC for the diagnosis of airflow obstruction. Pre and postbronchodilator spirometry, total lung volumes, and DLCO based on standard American Thoracic Society criteria using body plethysmography were used to assess airflow obstruction. To be eligible for participation, patients had postbronchodilator FEV1/FVC ratios <70% and were either smokers presently or in the past. Nonsmokers and patients with a history of asthma or other pulmonary conditions were excluded. Concordance between the 2 diagnostic ratios was compared as the difference in absolute percentage between postbronchodilator FEV1/FVC and FEV1/FEV6, using standard statistical tests to derive comparisons.

Of 600 consecutive patients, a total of 83 (42 men and 41 women) met the study inclusion criteria. The mean difference between postbronchodilator FEV1/FVC % and postbronchodilator FEV1/FEV6 % was 7.9%±4.7%. When men and women were compared, a consistently greater disparity in values was seen between the genders (5.8%±4.2% for men vs 10%±4.2% for women). Men and women were comparable in age (70±7 years vs 71± 8 years) and body mass index (26.2±9 vs 27±5; P =.35). No differences in lung volumes were seen between the genders in terms of TLC % (110%±23% vs 103%±18%; P =.18) and DLCO measurements (50%±22% vs 50%±23% P =.8). Using postbronchodilator FEV1/FEV6 (ratio <0.7), 24% of women would have been classified as normal compared with only 7% of men (P =.03)

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The researchers concluded, “Routine use of FEV1/FEV6 ratio may lead to a significant degree of underdiagnosis of COPD in [women]. The physiology underlying these differences in spirometric characteristics needs to be better understood.”

Disclosure: One study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

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Aiyer A, Aiyer I, Surani Z, Schaefer P, Surani S. Use of the FEV1/FEV6 ratio in the diagnosis of COPD: influence of gender. Presented at: CHEST Annual Meeting 2019; October 19-23, 2019; New Orleans, LA. Abstract 1051.