FEV1 (Force Expiratory Volume)/FEV6 and FEV6 as an alternative for FEV1/FVC (Forced vital capacity) and FVC in the detection of airway obstruction.

Abstract

Objectives: To evaluate the use of FEV₆ and FEV₁/FEV₆ as an alternative of FVC and FEV₁/FVC in determining airways restriction and obstruction. Study Design: Cross sectional Study. Setting: Department of pulmonology, DHQ Hospital Faisalabad. Period: 6 months (January-June, 2017). Material & Methods: Sample size of 250 patients, with 45-80 years of age who can exhale for 6 seconds were included in the study. Reference equations were used to detect lower normal limits (LNL) of FEV₆, FVC, FEV₁/FEV₆ and FEV₁/FVC. A person was said to have obstruction if FEV₁/FVC was below LNL. We considered a person to have restriction if FVC was below LNL without any obstructive pattern. FEV₁/FEV₆ and FEV₆ sensitivity and specificity were determined from this data. Results: Sensitivity of FEV_1/FEV₆ was 97.4% while specificity was 85.2%, in case of airway obstruction positive predictive value was 96.5% and negative predictive value was 88.5%. In case of restrictive pattern detected by spirometry a sensitivity of FEV6 was 96.5 % and 85.71 % was specificity 97.6% was PPVs and 80% was NPVs .Values were close to LNL in case when difference was noted between two indexes. Conclusion: Instead of FEV₁/FVC, FEV₁/FEV₆ can be used for diagnosing airway obstruction, particularly for screening population having high risk for COPD. For determining restrictive pattern by spirometry FEV₆ can also be used instead of FVC by providing less confusing and easier results.