Table 1.
Baseline characteristics of the population (N = 63) and quartiles of 6MWD normalized by squared height (m/m2)
| Characteristics | Population, N = 63 | 22–111 m/m2, n = 16 | 112–145 m/m2, n = 16 | 146–165 m/m2, n = 16 | 166–215 m/m2, n = 15 | P-value |
|---|---|---|---|---|---|---|
| Age | 71 (8) | 73.9 (6.9) | 71.6 (8.6) | 70.2 (6.8) | 68.2 (8.5) | 0.22 |
| Sex (M) | 38 (60.3) | 12 (75) | 11 (69) | 9 (56) | 6 (40) | 0.21 |
| Body mass index (kg/m2) | 28.1 (5.9) | 30.2 (7.1) | 31.1 (6.3) | 25.2 (2.8) | 25.8 (4.5) | 0.004 |
| mMRC | ||||||
| 0–1 | 43 (68) | 6 (37) | 13 (81) | 12 (75) | 12 (80) | 0.01 |
| ≥2 | 20 (32) | 10 (63) | 3 (19) | 4 (25) | 3 (20) | 0.01 |
| Exacerbation/year | ||||||
| 0–1 | 48 (76) | 13 (81) | 10 (63) | 12 (75) | 13 (87) | 0.46 |
| ≥2 | 15 (24) | 3 (19) | 6 (37) | 4 (25) | 2 (13) | 0.46 |
| Smoking habit | ||||||
| Current smokers | 25 (39.7) | 5 (31) | 7 (44) | 8 (50) | 5 (33) | 0.6 |
| Former smokers | 32 (50.8) | 9 (56) | 9 (56) | 7 (43) | 7 (47) | 0.6 |
| Pack/year | 35.1 (26.6) | 41.2 (30) | 40.9 (26.7) | 26.4 (18) | 31.7 (28) | 0.32 |
| GOLD classification 2014 | ||||||
| GOLD A | 35 (55.6) | 4 (25) | 9 (56) | 11 (69) | 11 (73) | 0.01 |
| GOLD B | 9 (14.5) | 5 (31) | 0 (0) | 2 (13) | 2 (13) | 0.01 |
| GOLD C | 8 (12.4) | 1 (6) | 3 (19) | 2 (13) | 2 (13) | 0.01 |
| GOLD D | 11 (17.5) | 6 (38) | 4 (25) | 1 (6) | 0 (0) | 0.01 |
| BODE index | 1 (0–3) | 3 (2–5) | 1 (0–3) | 0 (0–1) | 0 (0–1) | <0.001 |
| Spirometry | ||||||
| FEV1/FVC | 63.2 (9.6) | 61.5 (12.6) | 61.5 (9.2) | 65 (8.4) | 65 (7.3) | 0.55 |
| FEV1 (cm3) | 1.7 (0.7) | 1.5 (0.6) | 1.7 (0.5) | 2 (1) | 1.8 (0.5) | 0.2 |
| FEV1% | 69.6 (22.3) | 57.9 (22) | 64.6 (20.7) | 78.6 (27) | 77.7 (9.4) | 0.02 |
| FVC (cm3) | 2.8 (1) | 2.5 (1.1) | 2.7 (0.6) | 3.1 (1.4) | 2.8 (0.9) | 0.45 |
| FVC% | 86.3 (22.6) | 72.4 (21.5) | 82.3 (23.1) | 94.7 (25.2) | 96.3 (9.8) | 0.006 |
| TLC (cm3) | 5.9 (1.6) | 5.9 (1.5) | 5.8 (1.2) | 6.6 (2.1) | 5.3 (1.4) | 0.17 |
| TLC% | 100.9 (24.7) | 97.2 (40.7) | 92.4 (13.7) | 114.1 (15) | 100.2 (17) | 0.1 |
| RV/TLC (cm3) | 52.5 (11.5) | 57.5 (10.9) | 49.4 (15.4) | 52 (9.5) | 51.5 (8.5) | 0.29 |
| RV/TLC% | 126.5 (26.5) | 132.4 (29.8) | 124.7 (31) | 125.4 (22) | 123.9 (23) | 0.84 |
| Arterial gas analysis | ||||||
| pH | 7.41 (0.03) | 7.41 (0.02) | 7.42 (0.03) | 7.42 (0.03) | 7.42 (0.04) | 0.13 |
| pO2 (mmHg) | 77.6 (10.7) | 74.4 (11.4) | 74.5 (9.9) | 77.8 (11) | 84 (8.5) | 0.04 |
| pCO2 (mmHg) | 39.3 (5) | 41 (6.3) | 40.2 (3) | 39.2 (5.5) | 36.5 (4) | 0.08 |
| SO2 | 95.1 (1.7) | 94.5 (1.7) | 94.7 (1.7) | 95.2 (1.8) | 96.1 (0.9) | 0.04 |
| Multidimensional assessment | ||||||
| CIRS comorbidity index | 0 (0–1) | 0 (0–1) | 1 (0–2) | 0 (0–1) | 0 (0–1) | 0.2 |
| CIRS severity index | 0.7 (0.4) | 0.7 (0.4) | 0.8 (0.3) | 0.5 (0.2) | 0.7 (0.4) | 0.16 |
| MMSE | 27.9 (2.9) | 27.5 (2.4) | 28.9 (1.7) | 27.4 (3.5) | 27.7 (3.7) | 0.4 |
| Clock test | 11 (2.8) | 11.2 (2.8) | 11.2 (2) | 10.8 (3.5) | 10.9 (2.9) | 0.95 |
| ADL | 5.8 (0.5) | 5.8 (0.4) | 5.6 (0.8) | 5.9 (0.2) | 5.8 (0.4) | 0.4 |
| IADL | 7.7 (1) | 7.4 (1.5) | 7.6 (1) | 7.9 (0.5) | 7.9 (0.3) | 0.34 |
| GDS | 1.8 (2.7) | 2 (3.6) | 2.6 (3.2) | 1 (1.7) | 1.7 (1.6) | 0.4 |
| Blood analysis | ||||||
| WBC count (×103/µL) | 7.1 (1.7) | 7.5 (1.5) | 6.8 (1.7) | 6.9 (1.9) | 7 (1.5) | 0.68 |
| Hb (g/dL) | 14.2 (1.4) | 13.9 (1.9) | 14.4 (1.4) | 14.3 (1) | 14.3 (1.5) | 0.81 |
| ESR (mm/h) | 25.9 (23.7) | 35.6 (36.1) | 22.8 (15.9) | 20.9 (18.7) | 25.9 (20.9) | 0.42 |
| CRP (mg/L) | 3.2 (5.1) | 3.7 (4) | 1.4 (2.4) | 4.9 (7.9) | 2.3 (3.2) | 0.32 |
| Creatinine (mg/dL) | 1 (0.3) | 1.1 (0.3) | 0.9 (0.3) | 0.8 (0.2) | 0.9 (0.3) | 0.06 |
| eGFR(CKD-EPI) | 74.2 (19.5) | 64.2 (18) | 76.3 (21) | 80.6 (18.3) | 74.4 (18.9) | 0.15 |
| Vitamin D (ng/mL) | 20.9 (10.6) | 23.9 (12.3) | 20.5 (8.1) | 18.8 (7.8) | 20.5 (14) | 0.67 |
| Vitamin B12 (pg/mL) | 368.1 (204.7) | 338.8 (122.2) | 272.5 (122) | 449.1 (304) | 383.7 (150) | 0.2 |
| Folic acid (ng/mL) | 7.5 (7.2) | 5.5 (3.1) | 5.7 (2.5) | 9.9 (11.1) | 8.3 (6.7) | 0.38 |
| Bioimpedance analysis | ||||||
| Total body water % | 52.1 (6) | 51.4 (6.7) | 50.9 (5.4) | 54.5 (6.4) | 51.7 (5.3) | 0.31 |
| Fat mass % | 30.1 (8.4) | 32.1 (9.3) | 32.9 (6.4) | 25.8 (8.8) | 29.7 (7.3) | 0.07 |
| Fat-free mass % | 69.9 (8.4) | 67.9 (9.3) | 67.1 (6.4) | 74.2 (8.8) | 70.3 (7.3) | 0.06 |
Note: Continuous variables are shown as mean (standard deviation) or median (interquartile range), as appropriate, while categorical variables are shown as n (%).
Abbreviations: 6MWD, 6-minute walking test distance; ADL, activities of daily living; BODE, body mass index, obstruction, dyspnea and exercise; CIRS, Cumulative Illness Rating Scale; CRP, C-reactive protein; eGFR(CKD-EPI), estimated glomerular filtration rate (Chronic Kidney Disease Epidemiology Collaboration); ESR, erythrocyte sedimentation rate; FEV1, forced expiratory volume in the first second; FVC, forced vital capacity; GDS, Geriatric Depression Scale; GOLD, Global Initiative for Chronic Obstructive Lung Disease; Hb, hemoglobin; IADL, instrumental activities of daily living; mMRC, modified Medical Research Council; MMSE, mini-mental state examination; RV, residual volume; TLC, total leukocyte count; WBC, white blood cell.