Comparison between FEV₁/FEV₆ and FEV₁/FVC as screening of chronic obstructive pulmonary disease

To compare FEV₁/FEV₆ to the standard spirometry (FEV₁/FVC) as a screening tool for COPD.

This cross-sectional study was conducted at Hospital Tuanku Fauziah, Perlis, Malaysia from August 2015 to April 2016. FEV₁/FEV₆ and FEV₁/FVC results of 117 subjects were analysed. Demographic data and spirometric variables were tabulated. A scatter plot graph with Spearman's correlation was constructed for the correlation between FEV₁/FEV₆ and FEV1/FVC. The sensitivity, specificity, positive and negative predictive values of FEV₁/FEV₆ were determined with reference to the gold standard of FEV₁/FVC ratio <0.70. Receiver-operator characteristic (ROC) curve analysis and Kappa statistics were used to determine the FEV₁/FEV₆ ratio in predicting an FEV₁/FVC ratio <0.70.

Spearman's correlation with r = 0.636 (P<0.001) was demonstrated. The area under the ROC curve was 0.862 (95% confidence interval [CI]: 0.779 - 0.944, P<0.001). The FEV₁/FEV₆ cut-off with the greatest sum of sensitivity and specificity was 0.75. FEV₁/FEV₆ sensitivity, specificity, positive and negative predictive values were 93.02%, 67.74%, 88.89% and 77.78% respectively. There was substantial agreement between the two diagnostic cut-offs (κ = 0.634; 95% CI: 0.471 - 0.797, P<0.001) CONCLUSIONS: The FEV₁/FEV₆ ratio can be considered to be a good alternative to the FEV₁/FVC ratio for screening of COPD. Larger multicentre study and better education on spirometric techniques can validate similar study outcome and establish reference values appropriate to the population being studied.