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