Table 1 Baseline characteristics (Year 0) of participants according to quintiles of the Year 0 APDQS
| Â | Total participants | APDQS | P-value a | ||||
|---|---|---|---|---|---|---|---|
Quintile 1 (n = 720) | Quintile 2 (n = 817) | Quintile 3 (n = 773) | Quintile 4 (n = 737) | Quintile 5 (n = 740) | |||
APDQS, mean ± SD | 63.5 ± 13.1 | 45.9 ± 4.5 | 55.5 ± 2.3 | 62.9 ± 2 | 70.6 ± 2.5 | 83.2 ± 5.8 |  |
Age Y0, mean ± SD, y | 25.1 ± 3.6 | 23.2 ± 3.7 | 24.6 ± 3.7 | 25.3 ± 3.6 | 25.7 ± 3.2 | 26.5 ± 2.9 |  < 0.001 |
Female, no (%) | 2150 (56.8) | 378 (52.5) | 432 (52.9) | 426 (55.1) | 404 (54.8) | 510 (68.9) |  < 0.001 |
Self-identified race, no (%) | |||||||
 Black | 1792 (47.3) | 558 (77.5) | 538 (65.9) | 386 (49.9) | 227 (30.8) | 83 (11.2) |  < 0.001 |
 White | 1995 (52.7) | 162 (22.5) | 279 (34.2) | 387 (50.1) | 510 (69.2) | 657 (88.8) |  |
Maximal educational attainment, mean ± SD, grades b | 15.7 ± 2.6 | 14.6 ± 2.4 | 15 ± 2.5 | 15.6 ± 2.6 | 16.4 ± 2.5 | 17.1 ± 2.2 |  < 0.001 |
Study center, no (%) | |||||||
 Birmingham, AL | 882 (23.3) | 253 (35.1) | 249 (30.5) | 185 (23.9) | 127 (17.2) | 68 (9.2) |  < 0.001 |
 Chicago, IL | 836 (22.1) | 163 (22.6) | 178 (21.8) | 158 (20.4) | 168 (22.8) | 169 (22.8) |  |
 Minneapolis, MN | 975 (25.8) | 155 (21.5) | 192 (23.5) | 203 (26.3) | 214 (29.0) | 211 (28.5) |  |
 Oakland, CA | 1094 (28.9) | 149 (20.7) | 198 (24.2) | 227 (29.4) | 228 (30.9) | 292 (39.5) |  |
Height, mean ± SD, cm | 170.3 ± 9.5 | 169.9 ± 10 | 170.3 ± 9.9 | 170.4 ± 9.3 | 170.9 ± 9.5 | 169.7 ± 8.7 | 0.16 |
BMI, mean ± SD, kg/m2 | 24.5 ± 4.9 | 24.9 ± 5.8 | 24.9 ± 5.3 | 24.9 ± 5.1 | 24.2 ± 4.4 | 23.5 ± 3.6 |  < 0.001 |
Smoking, no (%) | |||||||
 Never | 2247 (59.7) | 463 (64.9) | 477 (58.7) | 455 (59.2) | 435 (59.5) | 417 (56.7) |  < 0.001 |
 Former | 521 (13.9) | 50 (7) | 79 (9.7) | 99 (12.9) | 117 (16.0) | 176 (23.9) |  |
 Current | 994 (26.4) | 201 (28.2) | 256 (31.5) | 215 (28) | 179 (24.5) | 143 (19.4) |  |
Pack-years smoking at Y0, mean ± SD, pack-years | 2.1 ± 4.3 | 1.9 ± 4.5 | 2.3 ± 4.3 | 2.2 ± 4.5 | 2 ± 4.3 | 1.9 ± 3.9 | 0.26 |
Pack-years smoking through Y20, mean ± SD, pack-years | 5.1 ± 9.4 | 5.4 ± 10 | 6.2 ± 10.4 | 5.5 ± 10.1 | 4.6 ± 8.4 | 3.5 ± 7.1 |  < 0.001 |
Total energy intake, mean ± SD, kcal | 2738 ± 1269 | 3050 ± 1351 | 2841 ± 1387 | 2785 ± 1334 | 2588 ± 1153 | 2420 ± 968 |  < 0.001 |
Physical activity, mean ± SD, EUc | 415.5 ± 292.9 | 349.7 ± 275.5 | 369.6 ± 289.6 | 406.5 ± 286.2 | 433.8 ± 272.5 | 521.6 ± 308.9 |  < 0.001 |
Cardiorespiratory fitness, mean ± SD, treadmill time, second | 591.5 ± 170.9 | 560.2 ± 168.5 | 558.1 ± 172 | 576.5 ± 171.1 | 616 ± 164.2 | 649.4 ± 159.7 |  < 0.001 |
History of asthma, no (%) | 179 (4.7) | 32 (4.5) | 39 (4.8) | 32 (4.2) | 34 (4.6) | 42 (5.7) | 0.77 |
FEV1, median (IQR), ml | 3470 (2950–4100) | 3280 (2810–3950) | 3350 (2850–4040) | 3480 (2980–4110) | 3640 (3080–4260) | 3540 (3130–4170) |  < 0.001 |
FVC, median (IQR), ml | 4170 (3530–5040) | 3960 (3280–4780) | 4020 (3370–4880) | 4190 (3520–5105) | 4370 (3670–5330) | 4250 (3780–5130) |  < 0.001 |
Ratio FEV/FVC, median (IQR), ml | 0.835 (0.792–0.873) | 0.843 (0.797–0.885) | 0.838 (0.796–0.878) | 0.835 (0.793–0.872) | 0.829 (0.784–0.863) | 0.833 (0.788–0.865) |  < 0.001 |
Ratio FEV1/FVC < 0.7 (Obstructive lung disease), no (%) | 125 (3.5) | 22 (3.3) | 22 (2.9) | 34 (4.6) | 26 (3.6) | 21 (2.9) | 0.39 |