Characteristics of the included study populations from the LifeLines and Vlagtwedde-Vlaardingen cohorts
| LifeLines | Vlagtwedde-Vlaardingen | |
|---|---|---|
| N with non-missing data | 11 851 | 2364 |
| Men, n (%) | 4878 (41) | 1265 (54) |
| Age (years), median (minimum–maximum) | 47 (18–89) | 52 (35–79) |
| Smoking status | ||
| Never, n (%) | 5091 (43) | 760 (32) |
| Ever, n (%) | 6760 (57) | 1604 (68) |
| Ex, n (%) | 4267 (36) | 753 (32) |
| Current, n (%) | 2493 (21) | 851 (36) |
| Packyears in ever smokers, median (25–75th centiles) | 10 (5–19) | 19 (9–31) |
| Lung function, mean (SD) | ||
| FEV1% predicted* | 103 (14) | 93 (16) |
| FEV1/FVC (%)† | 76 (7) | 74 (9) |
| Airway obstruction | ||
| No (FEV1/FVC≥70%), n (%) | 10 097 (85) | 1725 (73) |
| FEV1% predicted, mean (SD) | 105 (13) | 98 (13) |
| Mild (FEV1/FVC<70%), n (%) | 1754 (15) | 639 (27) |
| FEV1% predicted, mean (SD) | 89 (15) | 79 (16) |
| Moderate/severe‡, n (%) | 458 (4) | 314 (13) |
| FEV1% predicted, mean (SD) | 70 (9) | 67 (11) |
*FEV1% predicted is FEV1 as percentage predicted based on reference equations by Quanjer et al.16
†Vlagtwedde-Vlaardingen: FEV1/IVC.
‡Moderate/severe obstruction: subjects with moderate/severe obstruction=prebronchodilator FEV1/FVC<70% and FEV1<80%, subjects without obstruction=prebronchodilator FEV1/FVC≥70% and FEV1≥80%. Subjects with mild obstruction (prebronchodilator FEV1/FVC<70% and FEV1≥80% predicted) or prebronchodilator FEV1/FVC≥70% and FEV1<80% predicted were excluded from this analysis (LifeLines n=1517 (13%) and Vlagtwedde-Vlaardingen n=436 (18%)).