FEV1FEV6 : A Reliable, Easy-to-Use, and Cheaper Alternative to FEV1FVC in Diagnosing Airway Obstruction in Indian Population

Abstract EN

Background.

FEV1/FEV6 has been proposed as a cheap, reproducible and valid alternative to FEV1/FVC in spirometry.

No Indian data exists on its utility to diagnose airway obstruction.

Aim.

we sought to determine a fixed cut off of FEV1/FEV6 to diagnose obstruction corresponding to FEV1/FVC < 0.70 proposed by GOLD guidelines.

Method.

Spirometry was done on patient referred to a tertiary centre in India.

Age, sex, height weight were recorded in addition to spirometric variables like FEV1, FVC, FEV6.

The sensitivity, specificity, positive and negative predictive values of FEV1/FEV6 were determined with respect to gold standard of FEV1/FVC < 0.70.

Results.

467 spirometries were analysed after meeting the ATS acceptability criteria.

Considering FEV1/FVC < 0.7 as being the gold standard for obstruction, ROC curve was used to determine the best corresponding cut-off for FEV1/FEV6.

The area under the curve was 99.3% (95% CI: 98.1–99.8%), and the FEV1/FEV6 cut-off, corresponding to the greatest sum of sensitivity and specificity, was 73%.

For the total population, the FEV1/FEV6 sensitivity, specificity, PPV, NPV were was 95.7 %, 94.2 %, 87.5 % and 97.9 % respectively.

Agreement by Kappa value between two cut offs was excellent 0.89 (0.87–0.91).

Conclusion.

FEV1/FEV6 < 73% is a new reliable spirometry index to diagnose airway obstruction in Indian population.