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Table 4 Methods comparison (Bland-Altman statistics) for lung function measurements performed in a GP’s office and at lung function lab (N = 227)

From: Diagnostic accuracy of a pocket screening spirometer in diagnosing chronic obstructive pulmonary disease in general practice: a cross sectional validation study using tertiary care as a reference

  COPD-6™ at GP’s office
Lung function lab measurements   FEV1 (L) FEV6 (L) FEV1/FEV6 (%)
COPD-6™ FEV1 (L) Δ (95 % CI) 0.01 (−0.05 to 0.03) NA NA
FEV6 (L) Δ (95 % CI) NA −0.17 (−0.24 to −0.12)* NA
FEV1/FEV6 (%) Δ (95 % CI) NA NA 4.83 (3.71 to 6.35)*
Spirometry FEV1 (L) Δ (95 % CI) −0.12 (−0.15 to −0.09)* NA NA
FVC (L) Δ (95 % CI) NA −0.66 (−0.72 to -0.59)* NA
FEV1/FVC (%) Δ (95 % CI) NA NA 10.24 (9.32 to 11.26)*
Post-bronchodilator spirometry FEV1 (L) Δ (95 % CI) −0.15 (−0.19 to −0.12)* NA NA
FVC (L) Δ (95 % CI) NA −0.60 (−0.65 to −0.54)* NA
FEV1/FVC (%) Δ (95 % CI) NA NA 8.52 (7.57 to 9.47)*
  1. GP general practitioner, FEV 1 forced expiratory volume in 1 s, FEV 6 forced expiratory volume in 6 s, FVC forced expiratory volume, FVC forced expiratory volume, Δ mean difference of the index test (COPD-6™ measurement at GP’s office) from the reference (tertiary care measurement), 95 % CI 95 % confidence interval
  2. NA not applicable
  3. *P < 0.001