FEV1/FEV6 Cutoff Points to Avoid False Negatives When Using Portable Devices, PICO-6^® and COPD-6^®, in COPD Detection...

Background: Chronic obstructive pulmonary disease (COPD) is a frequent but underdiagnosed disease, primarily due to the lack of access to forced spirometry (FS) in primary care. Portable, easy-to-use expiratory flow meters like Piko-6^® and COPD-6^® that measure FEV₁, FEV₆, and FEV₁/FEV₆ ratio provide an alternative. Given that Piko-6^® and COPD-6^® devices measure FEV₆ but not FVC, the aim of the study is to determine the optimal cutoff value for the FEV₁/FEV₆ ratio of each device to avoid false negatives when these devices are used for COPD screening in primary care (PC). Methods: A total of 664 patients of 35 years of age or older with a cumulative tobacco consumption of 10 or more packs/year were recruited at two university hospitals. FS (gold standard) was performed and FEV₁, FVC, and FEV₁/FVC measurements were compared with FEV₁, FEV₆, and FEV₁/FEV₆ measurements acquired using Piko-6^® and COPD-6^® devices. The devices were compared using statistical methods including Pearson correlation coefficients, the Youden index (YI), kappa coefficient, Bland-Altman plots, and ROC curves analysis. Results: Correlations between FEV₁/FEV₆ using Piko-6^® and COPD-6^® and FEV₁/FVC with FS were 0.79 and 0.73, respectively. Piko-6^® achieved the best YI in FEV₁/FEV₆ (0.73), whereas for COPD-6^®, it was 0.80. Concordance between Piko-6^® and FS was 83.9% (kappa 0.67 ± 0.028) and for COPD-6^®, it was 68.7% (kappa 0.42 ± 0.02). Conclusions: This is the first study that compares two hand-held expiratory flow meters with FS. Piko-6^® and COPD-6^® devices are effective tools for COPD detection, as their measurements provide a good correlation with FS. In order to avoid false negative results, the FEV₁/FEV₆ cutoff point needs to be increased to 0.73 and 0.80 with Piko-6^® and COPD-6^®, respectively.