Baseline characteristics of 95 288 individuals according to clinical groups of airflow limitation (AFL) in the Copenhagen General Population Study
| No AFL | AFL | Potentially underdiagnosed AFL | Potentially overdiagnosed AFL | |||||
| (n=78 779) | (n=12 365) | (n=1056) | p versus No AFL | p versus AFL | (n=3088) | p versus No AFL | p versus AFL | |
| Age years | 56 (47–66) | 64 (55–72) | 45 (41–50) | <0.0001 | <0.0001 | 73 (67–80) | <0.0001 | <0.0001 |
| Male | 35 037 (44) | 6182 (50) | 434 (41) | 0.03 | <0.0001 | 1230 (40) | <0.0001 | <0.0001 |
| FEV1 % predicted | 98 (89–108) | 80 (66–91) | 90 (82–98) | <0.0001 | <0.0001 | 91 (80–102) | <0.0001 | <0.0001 |
| FVC % predicted | 99 (90–108) | 99 (85–11) | 104 (94–112) | <0.0001 | <0.0001 | 101 (88–113) | <0.0001 | <0.0001 |
| FEV1/FVC % | 79 (76–83) | 64 (60–67) | 71 (70–72) | <0.0001 | <0.0001 | 69 (68–70) | <0.0001 | <0.0001 |
| Smoking status | ||||||||
| Never smokers | 36 152 (46) | 2988 (24) | 416 (39) | <0.0001 | <0.0001 | 1034 (33) | <0.0001 | <0.0001 |
| Former smokers | 30 584 (39) | 5500 (44) | 345 (33) | <0.0001 | <0.0001 | 1518 (49) | <0.0001 | <0.0001 |
| Current smokers | 12 007 (15) | 3863 (31) | 294 (28) | <0.0001 | 0.02 | 533 (17) | 0.002 | <0.0001 |
| Cumulative tobacco consumption# | ||||||||
| Consumption pack-years | 14 (5–27) | 27 (14–42) | 16 (6–28) | 0.04 | <0.0001 | 21 (9–37) | <0.0001 | <0.0001 |
Data are presented as n (%) or median (25th–75th percentile). p-Values were obtained from Wilcoxon rank–sum or Pearson Chi-squared tests. No airflow limitation (AFL) was defined as forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ≥0.70 and FEV1/FVC ≥lower limit of normal (LLN). Potentially underdiagnosed AFL was defined as FEV1/FVC ≥0.70 and FEV1/FVC <LLN. Potentially overdiagnosed AFL was defined as FEV1/FVC <0.70 and FEV1/FVC ≥LLN. AFL was defined as FEV1/FVC <0.70 and FEV1/FVC <LLN. #: Consumption was only calculated for former and current smokers.