Differences in baseline characteristics of individuals according to tertiles of aryl hydrocarbon receptor repressor (AHRR) methylation extent and smoking status
| Methylation extent tertiles | Smoking status | ||||||
| Characteristic | All | Lowest | Middle | Highest | Current smokers | Former smokers | Never-smokers |
| Individuals n | 9113 | 3058 | 3053 | 3002 | 4426 | 2356 | 2331 |
| Methylation extent % | 56 (50–63) | 48 (46–50) | 56 (54–58) | 66 (63–69) | 50 (47–54) | 59 (54–64) | 64 (60–68) |
| Males | 4065 (45) | 1580 (52) | 1445 (47) | 1040 (35) | 2112 (48) | 1209 (51) | 744 (32) |
| Age years | 60 (47–70) | 58 (47–67) | 61 (48–71) | 60 (45–71) | 58 (47–67) | 64 (52–72) | 57 (42–71) |
| FEV1 z-score | −0.6 (−1.4–0.3) | −0.9 (−1.8–0.1) | −0.6 (−1.4–0.2) | −0.2 (−0.9–0.6) | −0.8 (−1.7–0) | −0.4 (−1.3–0.3) | −0.2 (−0.9–0.6) |
| FEV1/FVC | 0.79 (0.73–0.83) | 0.76 (0.70–0.81) | 0.78 (0.73–0.83) | 0.81 (0.76–0.85) | 0.77 (0.70–0.82) | 0.79 (0.73–0.83) | 0.81 (0.77–0.85) |
| Exposed to passive smoking | 3283 (36) | 1453 (48) | 1029 (34) | 801 (27) | 2109 (48) | 615 (26) | 559 (24) |
| Occupational exposures to dust and fumes | 1689 (19) | 768 (25) | 546 (18) | 375 (12) | 980 (22) | 443 (19) | 266 (11) |
| Completed higher education | 1837 (20) | 435 (14) | 641 (21) | 761 (25) | 707 (16) | 568 (24) | 562 (24) |
| Body mass index kg·m−2 | 25 (22–28) | 24 (22–27) | 25 (23–28) | 25 (23–28) | 24 (22–27) | 26 (23–29) | 25 (22–28) |
| Never-smokers | 2331 (26) | 34 (1.1) | 607 (20) | 1690 (56) | |||
| Current smokers | 4426 (49) | 2705 (88) | 1391 (46) | 330 (11) | |||
| Former smokers | 2356 (26) | 319 (10) | 1055 (35) | 982 (33) | |||
| Cumulative smoking pack-years# | 26 (14–40) | 32 (21–45) | 25 (13–40) | 13 (5.0–25) | 30 (18–43) | 20 (8.5–35) | 0 |
Data are presented as n (%) for categorical values and median (IQR) for continuous values, unless otherwise stated. FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; IQR: interquartile range. #: Calculated for current and former smokers only.