USE OF THE FEV1/FEV6 RATIO IN THE DIAGNOSIS OF COPD: INFLUENCE OF GENDER

Abstract

SESSION TITLE: Tuesday Abstract Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: 10/22/2019 01:00 PM - 02:00 PM PURPOSE: FVC is a difficult maneuver for many patients, and forced expiratory volume in 6 seconds (FEV6) has been proposed as a surrogate for FVC for the diagnosis of chronic obstructive pulmonary disease (COPD). It has been suggested that FEV1/FEV6 can be substituted for FEV1/FVC in diagnosing airflow obstruction and may better predict COPD-related pathology and morbidity. We wanted to study the influence of gender in a real world community based setting in the discrepancy between these 2 spirometric measures of COPD. METHODS: The study was done at a community based pulmonary practice setting. Airflow obstruction was assessed by performing pre- and postbronchodilator spirometry, total lung volumes and diffusion capacity (DLCO) based on standard ATS criteria using body plethysmography. For purpose of this study we only included patients who had a postbronchodilator FEV1/FVC ratio of less than 70% and were smokers (either at present or in the past). We excluded patients with a history of asthma or other pulmonary conditions, and nonsmokers. Concordance between the two ratios in diagnosing COPD was compared as difference in absolute % between post BD FEV1/FVC and FEV1/FEV6. Standard statistical tests were employed for deriving comparisons. RESULTS: We reviewed a total of 600 consecutive PFTs. A total of 83 patients - 42M and 41F - met our inclusion criteria for COPD. The mean difference between post-BD FEV1/FVC % and post BD FEV1/FEV6 % was 7.9 +/- 4.7 %. When we compared across genders, there was a consistently greater disparity in these values between men and women (5.8 +/- 4.2% vs 10 +/- 4.2% respectively). Mean and women were comparable in terms of age (70 +/- 7 vs 71 +/- 8) BMI (26.2 +/- 9 vs 27 +/- 5; p 0.35). There was also no gender difference in lung volumes in terms of Total Lung Capacity TLC % (110 +/- 23 vs 103 +/- 18; p = 0.18) and diffusion capacity DLCO measurements (50 +/- 22 vs 50 +/- 23% p = 0.8). 24% of females would have been classified as normal using post BD FEV1/FEV6 (ratio < 0.7) vs only 7% in males (p = 0.03). CONCLUSIONS: In a real world community setting there is significant disparity in the values of post DB FEV1/FEV6 and FEV1/FVC %. There is a strong gender influence with this disparity seen to be very pronounced in females despite there being no differences in age, BMI, as well as TLC and DLCO to account for this difference. CLINICAL IMPLICATIONS: Routine use of FEV1/FEV6 ratio may lead to a significant degree of underdiagnosis of COPD in females. The physiology underlying these differences in spirometric characterisitcs needs to be better understood. DISCLOSURES: No relevant relationships by Akshar Aiyer, source=Web Response No relevant relationships by Ishan Aiyer, source=Web Response No relevant relationships by Paul Schaefer, source=Web Response No relevant relationships by Zoya Surani, source=Web Response Speaker/Speaker's Bureau relationship with Astra Zaneca, Sunovian, Paratek Please note: $1001 - $5000 Added 01/13/2019 by Salim Surani, source=Web Response, value=Consulting fee