Table 1.
Baseline Characteristics according to Presence of Early COPD among Individuals under 50 Years of Age with 10 Pack-Years or Greater of Tobacco Consumption in the Copenhagen General Population Study
| No COPD (n = 6,889) | Early COPD (n = 1,175) | |
|---|---|---|
| General characteristics | ||
| Age, yr | 45.0 (42.0–47.6) | 45.9 (42.8–48.1)* |
| Sex, M, no. (%) | 3,181 (46) | 490 (42)* |
| BMI, kg/m2 | 25.7 (23.4–28.7) | 24.6 (22.5–27.3)* |
| FEV1 predicted, % | 97 (88–105) | 83 (74–92)* |
| FVC predicted, % | 99 (90–107) | 101 (90–111)* |
| FEV1/FVC | 0.79 (0.76–0.83) | 0.68 (0.65–0.70)* |
| Current smokers, no. (%) | 3,167 (46) | 678 (58)* |
| Tobacco consumption, pack-years | 18.8 (13.5–26.0) | 22.5 (15.0–30.0)* |
| Age at smoking initiation, yr | 15.0 (14.0–17.0) | 15.0 (14.0–17.0)* |
| Poor socioeconomic status, no. (%) | 1,123 (16) | 233 (20)* |
| Clinical characteristics, no. (%) | ||
| FEV1 < LLN of predicted | 638 (9) | 492 (42)* |
| FEV1 < 80% of predicted | 596 (9) | 471 (40)* |
| FEV1 < 50% of predicted | 2 (<1) | 32 (3)* |
| FEV1/FVC < 0.70 | 2 (<1) | 879 (75)* |
| Chronic mucus hypersecretion | 722 (10) | 234 (20)* |
| Dyspnea | 2,307 (33) | 538 (46)* |
| mMRC ≥2 | 454 (7) | 124 (11)* |
| Night-time dyspnea | 293 (4) | 108 (9)* |
| Wheezing | 1,867 (27) | 543 (46)* |
| Cough | 1,339 (19) | 378 (32)* |
| First-degree relative with asthma | 1,347 (20) | 336 (29)* |
| Childhood asthma/allergy | 1,259 (18) | 280 (24)* |
| Asthma | 354 (5) | 180 (15)* |
| Treatment with airway medication | 245 (4) | 155 (13)* |
| Physically inactive | 763 (11) | 162 (14)* |
| Bronchitis/pneumonia episodes in the last 10 yr | 1,868 (27) | 414 (35)* |
| General practitioner visits in the last 12 mo | 5,280 (77) | 947 (81)* |
| Alpha-1 antitrypsin < 1 g/L | 648 (9) | 107 (9) |
| Blood eosinophils ≥ 300 cells/μl | 1,304 (19) | 254 (22)* |
Definition of abbreviations: BMI = body mass index; COPD = chronic obstructive pulmonary disease; LLN = lower limit of normal; mMRC = modified Medical Research Council dyspnea scale.
Data presented as median (25th–75th percentiles) or number (%). Early COPD was defined as FEV1/FVC less than LLN.
*
P < 0.05 for comparison with individuals without COPD, obtained from Wilcoxon’s rank-sum, Pearson’s χ2 tests, or Fischer’s exact test.