Table 1.
Differences in measurements between different types of spirometers, spirometers of same type, and repeated measurements with a spirometer
| Spirometers | FVC | FEV1 | ||||
|---|---|---|---|---|---|---|
| Mean diff. (L) | Mean rel. diff. (%) | Bland–Altman 95% lim. agr. | Mean diff. (L) | Mean rel. diff. (%) | Bland–Altman 95% lim. agr. | |
| HW–US | 0.33*** | 8.99 | (0.09, 0.58) | 0.11*** | 3.59 | (− 0.03, 0.24) |
| WB–US | 0.24*** | 6.56 | (0.02, 0.47) | 0.15*** | 5.13 | (− 0.06, 0.36) |
| HW–WB | 0.09* | 2.28 | (− 0.14, 0.31) | − 0.05 n.s. | − 1.46 | (− 0.25, 0.16) |
| HW1–US1 | 0.35*** | 9.52 | (0.01, 0.69) | 0.12** | 4.00 | (− 0.05, 0.29) |
| HW1–US2 | 0.36*** | 9.64 | (− 0.004, 0.72) | 0.18** | 5.99 | (− 0.04, 0.39) |
| HW2–US1 | 0.32*** | 8.53 | (0.03, 0.60) | 0.04 n.s. | 1.29 | (− 0.21, 0.29) |
| HW2–US2 | 0.32*** | 8.65 | (0.06, 0.57) | 0.09 n.s. | 3.22 | (− 0.14, 0.33) |
| HW3–US1 | 0.40*** | 10.79 | (− 0.02, 0.81) | 0.14* | 4.67 | (− 0.13, 0.41) |
| HW3–US2 | 0.40*** | 10.91 | (0.03, 0.77) | 0.20** | 6.67 | (− 0.07, 0.46) |
| HW4–US1 | 0.25** | 6.86 | (− 0.06, 0.57) | 0.02 n.s. | 0.53 | (− 0.16, 0.19) |
| HW4–US2 | 0.26*** | 6.98 | (− 0.02, 0.54) | 0.07 n.s. | 2.45 | (− 0.15, 0.30) |
| WB–US1 | 0.24*** | 6.50 | (− 0.002, 0.48) | 0.12* | 4.14 | (− 0.10, 0.34) |
| WB–US2 | 0.24*** | 6.62 | (0.02, 0.47) | 0.18** | 6.13 | (− 0.05, 0.40) |
| HW1–WB | 0.11 n.s. | 2.84 | (− 0.19, 0.41) | − 0.004 n.s. | − 0.13 | (− 0.24, 0.23) |
| HW2–WB | 0.08 n.s | 1.91 | (− 0.18, 0.33) | − 0.09 n.s. | − 2.74 | (− 0.37, 0.20) |
| HW3–WB | 0.16 n.s. | 4.02 | (− 0.26, 0.58) | 0.02 n.s. | 0.51 | (− 0.31, 0.33) |
| HW4–WB | 0.01 n.s. | 0.34 | (− 0.21, 0.24) | − 0.11* | − 3.46 | (− 0.30, 0.09) |
| HW1–HW2 | 0.04 n.s. | 0.91 | (− 0.31, 0.38) | 0.08 n.s. | 2.68 | (− 0.25, 0.41) |
| HW1–HW3 | − 0.05 n.s. | − 1.14 | (− 0.43, 0.34) | − 0.02 n.s. | − 0.64 | (− 0.31, 0.27) |
| HW1–HW4 | 0.10 n.s. | 2.49 | (− 0.21, 0.41) | 0.10 n.s | 3.45 | (− 0.14, 0.35) |
| HW2–HW3 | − 0.08 n.s. | − 2.04 | (− 0.47, 0.30) | − 0.10 n.s. | − 3.23 | (− 0.36, 0.16) |
| HW2–HW4 | 0.06 n.s. | 1.56 | (− 0.17, 0.29) | 0.02 n.s. | 0.75 | (− 0.19, 0.23) |
| HW3–HW4 | 0.15 n.s. | 3.67 | (− 0.25, 0.54) | 0.12 n.s | 4.12 | (− 0.14, 0.38) |
| US1–US2 | 0.004 n.s. | 0.11 | (− 0.1, 0.13) | 0.06 n.s. | 1.91 | (− 0.09, 0.20) |
| Repeatability | FVC | FEV1 | ||||
|---|---|---|---|---|---|---|
| Mean diff. (L) | Mean rel. diff. (%) | ATS/ERS approved | Mean diff. (L) | Mean rel. diff. (%) | ATS/ERS approved | |
| HW1 | 0.05 | 1.31 | Yes | 0.05 | 1.70 | Yes |
| HW2 | 0.03 | 0.63 | Yes | 0.03 | 1.03 | Yes |
| HW3 | 0.06 | 1.51 | Yes | 0.04 | 1.30 | Yes |
| HW4 | 0.04 | 1.09 | Yes | 0.03 | 1.15 | Yes |
| US1 | 0.04 | 1.07 | Yes | 0.03 | 1.07 | Yes |
| US2 | 0.05 | 1.35 | Yes | 0.05 | 1.62 | Yes |
| WB | 0.03 | 0.64 | Yes | 0.03 | 0.84 | Yes |
Repeatability: difference between best and second best test, Mean difference: e.g. HW–US, Mean relative difference: e.g. HW–US/US*100
diff difference, HW hot-wire, lim. agr. limits of agreement, n.s. not significant, rel relative, US ultrasonic, WB wedge-bellows
* p < 0.05, ** p < 0.01,*** p < 0.001 (Bonferroni-corrected from linear mixed models, n = 12)