Case identification of subjects with airflow limitations using the handheld spirometer "Hi-Checker™" : comparison against an electronic desktop spirometer

Abstract

Background: Systematic case identification has been proposed as a strategy to improve diagnosis rates and to enable the early detection of subjects with COPD. We hypothesized that case identification could be possible using the handheld spirometer Hi-Checker™.

Aim: To determine how to modify the FEV(1)/FEV(6) values obtained using the Hi-Checker™ to screen for cases with airflow limitation.

Methods: Spirometry was performed with both an electronic desktop spirometer and with the Hi-Checker™ in 312 male subjects.

Results: The average FEV(1) (mean ± SD) measured using a conventional spirometer and the Hi-Checker™ was 2.99 ± 0.56L and 3.07 ± 0.57L, respectively. These results were significantly different (P<0.001, paired t-test for both). This difference of -0.08 ± 0.13L (95% confidence interval: -0.094-0.066L) was normally distributed, and thought to be random. Statistically significant correlations were found for all measurements between the spirometer and the Hi-Checker™ ; the Pearson's correlation coefficient (R) between the FEV(1)/FVC and FEV(1)/FEV(6) values was 0.881. If one defines a FEV(1/)FVC smaller than 0.7 measured by the spirometer as airflow limitation, then a FEV(1)/FEV(6) smaller than 0.746 measured by the Hi-Checker™ best matches this definition, and Cohen's kappa coefficient was 0.672.

Conclusion: Although the Hi-Checker™ estimates resembled those from conventional spirometry, it should be emphasized that the two methods did not produce identical results due to random measurement error. Although one must be careful about overinterpreting these results, since the Hi-Checker™ is small and inexpensive, it could make a significant contribution in facilitating the case selection of patients with airflow limitation.