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Table 1 Differences in measurements between different types of spirometers, spirometers of same type, and repeated measurements with a spirometer

From: A pilot study of hot-wire, ultrasonic and wedge-bellows spirometer inter- and intra-variability

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
  1. Repeatability: difference between best and second best test, Mean difference: e.g. HW–US, Mean relative difference: e.g. HW–US/US*100
  2. diff difference, HW hot-wire, lim. agr. limits of agreement, n.s. not significant, rel relative, US ultrasonic, WB wedge-bellows
  3. p < 0.05, ** p < 0.01,*** p < 0.001 (Bonferroni-corrected from linear mixed models, n = 12)
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