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Table 1 Baseline characteristics

From: Diagnostic accuracy of capnovolumetry for the identification of airway obstruction – results of a diagnostic study in ambulatory care

Parameter   Presence of airway obstruction  
All (n = 1287) no (n = 916) yes (n = 371) Comparison between groups (p-value)
Gender (m/f) 589/698 385/531 204/167 < 0.001
BMI (kg/m2) 26.9 (23.7; 31.1) 27.0 (23.9; 31.2) 26.7 (23.4; 35.3) 0.288
Age (y) 59.0 (47.0; 70.0) 56.0 (42.8; 77.0) 62.0 (53.0; 79.0) < 0.001
FEV1 z-Score −0.92 (−1.98; − 0.05) −0.47 (− 1.09; 0.24) − 2.47 (− 3.16; − 1.65) < 0.001
FEV1/FVC 74.9 (66.2; 81.4) 78.6 (74.1; 83.8) 59.8 (48.9; 70.9) < 0.001
FEV1/FVC z-Score − 0.63 (− 1.72; 0.25) − 0.12 (− 0.74; 0.54) −2.44 (− 3.3; − 1.77) < 0.001
FVC z-Score −0.58 (− 1.41; 0.20) −0.37 (− 1.05; 0.38) − 1.22 (− 2.02; − 0.33) < 0.001
sRaw (kPa*s) 0.54 (0.27; 1.04) 0.39 (0.20; 0.62) 1.51 (0.85; 2.54) < 0.001
Raw (kPa*s/l) 0.20 (0.10; 0.35) 0.14 (0.08; 0.23) 0.45 (0.28; 0.71) < 0.001
FRCpleth z-Score −0.40 (− 1.16; 0.57) − 0.66 (− 1.32; 0.08) 0.30 (− 0.56; 1.32) < 0.001
Smoking status (current/ex/never) 253/485/536 154/303/447 99/182/89 < 0.001
  1. The table shows absolute numbers in case of frequencies, median values and quartiles in case of continuous parameters. The groups were compared with each other using the Mann-Whitney-U-test, the categorical variables were compared using the Chi-square statistics. FEV1, forced expiratory volume in one second; FVC, forced vital capacity; sRaw, specific airway resistance (effective); FRCpleth, functional residual capacity determined by bodyplethysmography. Z-Scores were computed using the respective prediction equations [20]. The groups were statistically significantly different from each other in all parameters except BMI. Among the 371 patients with airway obstruction, 108 (29%) had asthma, 223 (60%) COPD, 24 (7%) the diagnosis of other respiratory diseases (such as restrictive disorders, pneumonia or other infections, pleural diseases, lung tumor, bronchiectasis), while in 16 (4%) of these patients no respiratory disease was found. Among the 916 patients without airway obstruction, 325 (35%) had asthma verified by bronchial provocation, 243 (27%) suffered from other respiratory diseases (such as restrictive disorders, pneumonia or other infections, pleural diseases, lung tumor, bronchiectasis, chronic bronchitis), and 348 (38%) had no respiratory disease