Table 3.
Comparison between current or former smoker subjects according to the lung diffusing capacity*
| Reduced DLCO (n=34) |
Normal DLCO (n=138) |
P value | |
| Females, n (%) | 21 (61.8) | 68 (49.3) | 0.133 |
| Age, years | 54 (48–64) | 60 (54–67) | 0.028 |
| BMI, kg/m2 | 26.7 (21.6–29.1) | 27.1 (24.4–30.0) | 0.237 |
| Level of studies | 0.070 | ||
| No studies | 1 (2.9) | 0 | |
| Primary education | 7 (20.6) | 24 (17.4) | |
| Secondary education | 6 (17.6) | 31 (22.5) | |
| University | 19 (55.9) | 83 (60.1) | |
| Lives alone | 5 (14.7) | 31 (22.5) | 0.227 |
| Pack-years | 25 (20–39) | 30 (20–40) | 0.529 |
| Fagerström test | 4 (3–6) | 4 (2–5) | 0.682 |
| Charlson Comorbidity Index | 0.4±0.8 | 0.4±1.0 | 0.861 |
| COTE index | 1.9±2.7 | 0.9±2.0 | 0.066 |
| CAT total score | 5.0 (4.5–15.5) | 4 (2-8) | 0.531 |
| mMRC dyspnoea level | 0.037 | ||
| 0 | 23 (67.6) | 105 (76.1) | |
| 1 | 8 (23.5) | 30 (21.7) | |
| 2 | 1 (2.9) | 3 (2.2) | |
| 3 | 2 (5.9) | 0 | |
| Chronic cough, n (%) | 8 (24.2) | 31 (22.6) | 0.503 |
| Chronic bronchitis, n (%) | 2 (6.9) | 11 (8.5) | 0.565 |
| Chronic expectoration, n (%) | 7 (20.6) | 28 (20.6) | 0.604 |
| Wheezing, n (%) | 15 (44.1) | 54 (39.4) | 0.378 |
| Baseline oxygen saturation, % | 97 (96–97) | 96 (96–97) | 0.863 |
| Exhaled CO, ppm | 31 (29–32) | 12 (2–31) | 0.006 |
| Prebronchodilator FVC, z-score | −0.43 (−1.00 to 0.40) | 0.36 (−0.29 to 0.95) | <0.001 |
| Prebronchodilator FEV1, z-score | −0.44 (−1.32 to −0.10) | 0.03 (−0.54 to 0.91) | 0.001 |
| Prebronchodilator FEV1/FVC, z-score | −0.48 (−0.85 to −0.06) | −0.34 (−0.99 to 0.28) | 0.501 |
| Reduced VA, n (%) | 3 (8.8) | 2 (1.4) | 0.053 |
| 6MWD, m | 465 (450–480) | 555 (533–605) | 0.047 |
| Haemoglobin, g/L | 147 (144–149) | 153 (148–170) | 0.821 |
| Eosinophils, % | 0.1 (0.1–0.1) | 0.2 (0.1–1.9) | 0.435 |
| Fibrinogen, mg/dL | 4.4 (3.9–4.9) | 3.5 (2.9–4.1) | 0.698 |
| C reactive protein, mg/L | 0.7 (0.2–1.3) | 0.4 (0.1–3.5) | 0.404 |
| Albumin | 4.2 (4.2–4.3) | 4.7 (4.6–39.6) | <0.001 |
| BODE index | 0.006 | ||
| 0–2 points (survival: 80%) | 30 (88.2) | 137 (99.3) | |
| 3–4 (survival: 67%) | 4 (11.8) | 1 (0.7) | |
| Physical activity summary | 29 (24–62) | 53 (34–69) | 0.048 |
| Total emphysema volume, % | 0.69 (0.18–2.80) | 0.34 (0.17–2.79) | 0.261 |
| Low density volume, % | 53 (34–63) | 48 (24–54) | 0.210 |
| P15, HU | −911 (−917 to −886) | −905 (−930 to −889) | 0.127 |
| Secondary bronchi WA, % | 25.8 (22.8–27.5) | 25.3 (20.2–29.8) | 0.928 |
| Pulmonary artery diameter, mm | 25 (24–27) | 23 (21–24) | 0.002 |
| Pulmonary artery:aorta ratio | 0.77 (0.72–0.79) | 0.70 (0.65–0.71) | 0.578 |
| Pulmonary artery enlargement | 8 (26.7%) | 16 (13.4%) | 0.095 |
Comparisons were performed by Student’s t-test, Mann-Whitney U or χ2 tests.
Bold values highlight significant differences.
*Data are mean±SD, median (IQR) or number (frequency) according to their type and distribution.
BMI, body mass index; BODE, body obstructive dyspnoea exercise; CAT, chronic obstructive pulmonary disease assessment test; CO, carbon monoxide; DLCO, lung diffusing capacity for carbon monoxide; FEV1, forced expiratory volume at 1 s; FVC, forced vital capacity; LLN, lower limit of normal; mMRC, modified Medical Research Council; 6MWD, 6 min walk distance; P15, 15th percentile; VA, alveolar volume; WA, wall airway.