Table 1

Baseline characteristics of the study population across quintiles of FEV1s

Characteristic*Quintiles of FEV1 measure†Total
Q1 (lowest)Q2Q3Q4Q5 (highest)
No. of participants2941294229422942294114 708
Age, years56.6 (5.5)54.9 (5.6)53.8 (5.6)53.6 (5.8)52.5 (5.4)54.3 (5.8)
Males (%)440 (15.0)563 (19.1)958 (32.6)1923 (65.4)2825 (96.1)6709 (45.6)
White (%)1709 (58.1)2022 (68.7)2253 (76.6)2378 (80.8)2636 (89.6)10 998 (74.8)
Education (%)
 Less than high school1096 (37.3)880 (27.5)621 (21.1)582 (19.8)360 (12.3)3467 (23.6)
 High school1157 (39.4)1277 (43.5)1287 (43.8)1164 (39.6)1131 (38.5)6016 (41.0)
 College684 (23.3)853 (29.0)1029 (35.0)1193 (40.6)1446 (49.2)5205 (35.4)
Sitting height, cm84.6 (5.6)86.2 (4.6)88.0 (4. 6)90.4 (4.2)93.5 (4.2)88.6 (5.6)
Body mass index, kg/m2 28.7 (6.8)27.9 (5.8)27.3 (5.4)27.2 (4.7)27.3 (3.8)27.7 (5.4)
Systolic blood pressure, mm Hg126.5 (20.9)121.9 (19.7)119.8 (18.3)119.8 (18.3)118.3 (15.5)121.2 (18.9)
Diastolic blood pressure, mm Hg73.6 (12.2)72.8 (11.4)73.2 (11.0)74.0 (11.4)74.4 (10.3)73.6 (11.3)
Smoking status (%)
 Never1138 (18.8)1357 (22.5)1312 (21.7)1160 (19.2)1072 (17.8)6039 (41.1)
 Former647 (13.5)745 (15.6)910 (19.0)1118 (23.4)1367 (28.6)4787 (32.6)
 Current1156 (29.8)840 (21.6)720 (18.6)664 (17.1)502 (12.9)3882 (26.4)
Pack-years33.1 (11.2)29.4 (12.0)27.2 (12.3)26.7 (12.1)22.7 (11.3)27.8 (12.3)
Clinical history (%)
 Hypertension1425 (48.5)1107 (37.6)990 (33.7)907 (30.8)705 (24.0)5134 (34.9)
 Diabetes mellitus560 (19.0)379 (12.9)297 (10.1)301 (10.2)236 (8.0)1773 (12.1)
 Coronary heart disease160 (5.4)119 (4.0)143 (4.9)172 (5.9)129 (4.4)723 (4.9)
 Chronic heart failure312 (10.6)170 (5.8)118 (4.0)62 (2.1)47 (1.6)709 (4.8)
Total cholesterol, mg/dL221.0 (45.5)218.8 (43.3)214.9 (40.5)212.0 (40.3)209.3 (39.0)215.2 (42.0)
LDL-cholestrol, mg/dL140.1 (42.6)138.9 (40.3)136.0 (38.3)136.6 (38.2)138.2 (36.4)137.9 (39.2)
HDL-cholestrol, mg/dL53.9 (17.4)54.3 (17.2)54.2 (17.8)49.6 (17.1)44.8 (13.3)51.3 (17.0)
Triglycerides, mg/dL137.0 (91.0)132.5 (92.4)126.4 (86.9)132.0 (92.5)135.9 (91.4)132.7 (90.9)
 Fasting blood glucose, mg/dL114.8 (55.6)108.8 (44.1)106.0 (39.8)106.8 (35.2)105.0 (27.5)108.3 (41.6)
Markers of inflammation
 White cell count, ×103/mm3 6.4 (2.4)6.1 (2.1)5.9 (2.0)6.0 (2.0)5.9 (2.1)6.1 (2.1)
 Fibrinogen, mg/dL326.4 (80.9)308.4 (67.4)299.4 (65.0)294.9 (64.6)282.6 (58.0)302.2 (69.1)
 Albumin, g/dL3.8 (0.3)3.8 (0.3)3.9 (0.3)3.9 (0.3)4.0 (0.2)3.9 (0.3)
 Von Willebrand’s factor, %128.8 (56.4)121.7 (50.2)115.9 (47.5)113.7 (44.8)109.9 (43.5)118.0 (49.1)
Electrographic findings
 Resting hear rate, bpm68.9 (11.1)67.2 (10.3)66.2 (9.9)65.3 (9.8)63.9 (9.8)66.3 (10.3)
 QTc, ms421.6 (22.0)419.3 (23.2)417.2 (18.8)413.7 (17.4)410.0 (17.7)416.4 (20.4)
 Left ventricular hypertrophy (%)114 (3.9)83 (2.8)57 (1.9)38 (1.3)27 (0.9)319 (2.2)
Spirometry
 FEV1, L1.8 (0.3)2.4 (0.1)2.7 (0.1)3.2 (0.2)4.0 (0.4)2.8 (0.8)
 FVC, L2.7 (0.5)3.2 (0.4)3.7 (0.4)4.2 (0.4)5.2 (0.6)3.8 (1.0)
 FEV1/FVC61.9 (7.5)71.7 (1.4)75.5 (1.0)78.7 (0.9)83.5 (2.9)74.3 (8.2)
 FEV1/FVC ratio <70% (%)1287 (43.8)642 (21.8)554 (18.8)514 (17.5)341 (11.6)3338 (22.7)
 FEV1%, predicted75.1 (17.7)91.7 (13.8)97.0 (14.7)97.8 (14.0)103.9 (10.4)93.1 (17.3)
 FVC%, predicted86.9 (15.0)99.3 (13.2)103.7 (14.0)103.9 (14.0)108.1 (11.0)100.4 (11.0)
Self-reported diagnosis (%)
 Bronchitis‡530 (18.0)309 (10.5)219 (7.4)178 (6.1)123 (4.2)1359 (9.2)
 Asthma371 (12.6)171 (5.8)151 (5.1)151 (5.1)127 (4.3)971 (6.6)
 Emphysema156 (5.3)37 (1.3)20 (0.7)32 (1.1)25 (0.9)270 (1.8)
Medications (%)
 Anticholinergics15 (0.5)0 (0)1 (0)1 (0)0 (0)17 (0.1)
 Beta-agonists148 (5.0)33 (1.1)11 (0.4)13 (0.4)13 (0.4)218 (1.5)
 Xanthines158 (5.4)40 (1.4)12 (0.4)20 (0.7)14 (0.5)244 (1.7)
 Inhaled corticosteroids24 (0.8)20 (0.7)8 (0.3)11 (0.4)11 (0.4)74 (0.5)
  • *Expressed as mean and SD or percentages.

  • †FEV1 measured using standardised spirometry at study baseline.

  • ‡Chronic bronchitis was defined as productive cough for at least 3 months in two contiguous years.

  • HDL, high-density lipoprotein; LDL, low-density lipoprotein.