The ETs were asked to perform PFTs in the two other centers to verify interchangeability of the results. There was no significant difference between centers in absolute values and reproducibility (p > 0.05, by one-way analysis of variance; Fig 1).
Precision of the Spirometers: The ETs were asked to perform on the same day five successive forced expiratory maneuvers with the standard spirometers (one by center) and with the office spirometers to compare their reproducibility. After verifying the interchangeability of the results, we pooled the values and reported the within-subjects SD (Sw). buy actos 30mg
Agreement Between the Standard and Office Spirometers: In each center, PFTs were performed by healthy naive subjects and 10 COPD patients with the office spirometers and with the standard spirometers. The healthy subjects were nonsmokers, free of any respiratory symptoms, and members of the hospital staff. These tests were done in a random order to avoid a learning effect. We asked the three centers to select the patients to represent various degrees of severity of COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stages I to IV). We retained only the patients and subjects able to perform the PFT according to American Thoracic Society (ATS) quality criteria. We compared the best values of FVC, FEV1, and FEVj/FVC from all acceptable tests for all pairs of devices (each office spirometer vs standard spirometer). Because of the multicentric nature of the study and the fact that the same devices were tested successively in each center, the healthy volunteers and the COPD patients were different for each apparatus and by center. Each office spirometer was tested with 48 subjects ([three ETs + 3 healthy subjects + 10 COPD patients] X 3), a sample size comparable to previous studies.
Figure 1. Plot of each set of five FVC measures in one ET in the three centers with the standard spirometers (C1 to C3) and with one office spirometer (OneFlow). The precision of FVC measurement was comparable between the three centers but differed with the office spirometer.