Table 1.
Baseline characteristics of the study population across quartiles of FEV1% predicted
| Quartiles of FEV1% predicted | |||||
|---|---|---|---|---|---|
| Characteristics | Q1 (lowest) | Q2 | Q3 | Q4 (highest) | Total |
| Age, yrs | 62.8 (9.9) | 59.2 (9.5) | 57.9 (9.2) | 57.9 (9.2) | 59.4 (9.7) |
| Males, % | 2540 (57.5) | 2267 (51.3) | 1911 (43.2) | 1373 (31.1) | 8091 (45.8) |
| White participants, % | 3589 (81.2) | 3448 (78.0) | 3534 (79.9) | 3532 (79.9) | 14,103 (79.8) |
| Education levels, % | |||||
| Low | 1498 (33.9) | 1210 (27.4) | 970 (21.9) | 871 (19.7) | 4549 (25.7) |
| Intermediate | 1896 (42.9) | 1876 (42.4) | 1985 (44.9) | 1940 (43.9) | 7697 (43.5) |
| High | 1026 (23.2) | 1335 (30.2) | 1466 (33.2) | 1610 (36.4) | 5437 (30.8) |
| Smoking status, % | |||||
| Never | 1064 (24.1) | 1678 (38.0) | 2082 (47.1) | 2520 (57.0) | 7344 (41.5) |
| Former | 1736 (39.3) | 1574 (35.6) | 1527 (34.5) | 1395 (31.6) | 6232 (35.2) |
| Current | 1620 (36.7) | 1169 (26.4) | 812 (18.4) | 506 (11.5) | 4107 (23.2) |
| Alcohol use, % | 2376 (54.8) | 2416 (54.7) | 2483 (56.2) | 2424 (54.8) | 9699 (54.9) |
| Body mass index, kg/m2 | 27.4 (5.3) | 27.8 (5.3) | 27.6 (5.1) | 27.2 (4.8) | 27.5 (5.1) |
| Systolic blood pressure, mmHg | 131.6 (21.9) | 127.3 (20.7) | 124.5 (19.8) | 123.0 (19.3) | 126.6 (20.7) |
| Diastolic blood pressure, mmHg | 72.8 (12.1) | 73.4 (11.6) | 73.1 (11.2) | 72.6 (10.7) | 73.0 (10.7) |
| Clinical history, % | |||||
| Hypertension | 2013 (45.5) | 1788 (40.4) | 1619 (36.6) | 1406 (31.8) | 6826 (38.6) |
| Diabetes mellitus | 774 (17.5) | 709 (16.0) | 539 (12.2) | 417 (9.4) | 2439 (13.8) |
| Coronary heart disease | 699 (15.8) | 450 (10.2) | 301 (6.8) | 207 (4.7) | 1657 (9.4) |
| Chronic heart failure | 379 (8.6) | 229 (5.2) | 172 (3.9) | 116 (2.6) | 896 (5.1) |
| Laboratory findings | |||||
| Total cholesterol, mmol/L | 5.5 (1.1) | 5.5 (1.1) | 5.6 (1.1) | 5.6 (1.1) | 5.6 (1.1) |
| LDL-cholestrol, mmol/L | 3.4 (1.1) | 3.5 (1.1) | 3.6 (1.0) | 3.6 (1.1) | 3.5 (1.1) |
| HDL-cholestrol, mmol/L | 1.3 (0.4) | 1.3 (0.4) | 1.3 (0.4) | 1.4 (0.4) | 1.3 (0.4) |
| Triglycerides, mmol/L | 1.6 (1.1) | 1.6 (1.0) | 1.5 (1.0) | 1.4 (0.9) | 1.6 (1.0) |
| Fasting blood glucose, mmol/L | 6.4 (2.5) | 6.2 (2.3) | 6.1 (2.2) | 5.9 (1.9) | 6.1 (2.3) |
| Electrographic findings | |||||
| Resting hear rate, bpm | 67.2 (11.0) | 66.1 (10.5) | 65.9 (9.9) | 66.1 (10.0) | 66.3 (10.4) |
| QTc, ms | 421.1 (46.5) | 417.5 (44.8) | 415.6 (49.1) | 416.3 (46.2) | 417.6 (46.7) |
| Left ventricular hypertrophy, % | 185 (4.2) | 137 (3.1) | 98 (2.2) | 79 (1.8) | 499 (2.8) |
| Spirometry | |||||
| FEV1% predicted | 64.7 (13.7) | 86.1 (3.5) | 97.4 (3.1) | 112.2 (8.3) | 90.1 (19.3) |
| FVC% predicted | 78.6 (13.5) | 93.3 (8.8) | 102.4 (8.5) | 115.0 (10.6) | 97.3 (16.9) |
| FEV1/FVC% predicted | 84.9 (17.0) | 96.1 (10.9) | 98.6 (9.4) | 101.0 (9.2) | 95.1 (13.6) |
| FEV1, L | 1.9 (0.6) | 2.5 (0.6) | 2.8 (0.7) | 3.1 (0.8) | 2.6 (0.8) |
| FVC, L | 3.0 (0.9) | 3.5 (0.9) | 3.8 (1.0) | 4.0 (1.0) | 3.6 (1.0) |
| FEV1/ FVC, % | 64.7 (11.9) | 73.4 (6.6) | 75.9 (5.5) | 77.8 (5.2) | 73.0 (9.3) |
| Self-reported symptoms, % | |||||
| Cough | 1061 (24.0) | 579 (13.1) | 435 (9.8) | 338 (7.7) | 2413 (13.7) |
| Phlegm | 1137 (25.7) | 615 (13.9) | 477 (10.8) | 402 (9.1) | 2631 (14.9) |
| Dyspnea | 1285 (29.1) | 703 (15.9) | 554 (12.5) | 436 (9.9) | 2978 (16.8) |
| Self-reported diagnosis, % | |||||
| Bronchitis | 964 (21.8) | 549 (12.4) | 447 (10.1) | 382 (8.6) | 2342 (13.2) |
| Asthma | 459 (10.4) | 258 (5.8) | 171 (3.9) | 148 (3.4) | 1036 (5.9) |
| Emphysema | 341 (7.7) | 71 (1.6) | 47 (1.1) | 23 (0.5) | 482 (2.7) |
| Cardiac medication, % | |||||
| Calcium antagonist | 403 (9.1) | 270 (6.1) | 223 (5.0) | 189 (4.3) | 1085 (6.1) |
| Digoxin | 291 (6.6) | 153 (3.5) | 109 (2.5) | 99 (2.2) | 652 (3.7) |
| β-Blocker | 474 (10.7) | 375 (8.5) | 305 (6.9) | 244 (5.5) | 1398 (7.9) |
Abbreviations: LDL Low-density lipoprotein, HDL High-density lipoprotein, FEV1 Forced expiratory volume in 1 s, FVC Forced vital capacity
Values are mean ± SD or number (percentage) of subjects