Table 1.
Clinical and experimental cohort characteristics
| Characteristics | Controls | Diff | COPDN | Diff | COPDL | Diff | p-value |
|---|---|---|---|---|---|---|---|
| Male/female | 8/2 | A | 8/2 | A | 8/2 | A | ns |
| Age (years) | 68.3±4.4 | 68.9±4.6 | 66.7±5.9 | ns | |||
| Height (m) | 1.74±0.08 | A | 1.70±0.09 | A | 1.67±0.08 | A | ns |
| Weight (kg) | 89.93±15.63 | A | 76.1±12.65 | A | 51.71±5.71 | B | 0.0001 |
| BMI (kg·m−2) | 30.6±6.9 | A | 26.0±2.2 | A | 18.9±1.9 | B | <0.0001 |
| FFM (kg) | 62.55±11.35 | A | 54.13±10.13 | A | 43±5.69 | B | <0.005 |
| FFMI (kg·m−2) | 20.4±2.7 | A | 18.6±1.4 | A | 15.3±0.7 | B | <0.0001 |
| Active/ex-smokers | 2/8 | A | 2/8 | A | 2/8 | A | ns |
| Number of cigarettes (pack-years) | 31.9±15.8 | A | 48.7±21 | A | 64.3±39.8 | A | ns |
| Average smoking cessation (years) | 23.2±17.3 | A | 8.4±7 | B | 5.4±7.4 | B | <0.01 |
| Age at smoking cessation (years) | 45.1±15.5 | A | 60.5±7.6 | B | 61.3±7.8 | B | <0.01 |
| mMRC | 2.9±1.3 | 4.1±1.1 | ns | ||||
| FEV1 (L) | 2.8±0.6 | A | 1.2±0.5 | B | 0.9±0.4 | B | <0.0001 |
| FEV1 (% predicted) | 94.4±12.6 | A | 44.1±18.3 | B | 33.2±13.7 | B | <0.0001 |
| FVC (L) | 3.9±0.7 | A | 2.7±1.1 | B | 2.6±1 | B | <0.01 |
| FVC (% predicted) | 103.7±10.1 | A | 87.8±28.5 | AB | 76.5±18.2 | B | <0.05 |
| FEV1/FVC | 0.7±0 | A | 0.4±0.1 | B | 0.3±0.1 | B | <0.0001 |
| PaO2 (mmHg) | 73.1±5.4 | A | 70.2±9.8 | 75.2±13.1 | ns | ||
| PaCO2 (mmHg) | 41.8±1.7 | A | 41±3.4 | 43.1±5.2 | ns | ||
| Physical activity (V) | 11.0±4.6 | A | 7.2±6 | B | 1.1±1 | C | <0.0001 |
| Physical activity (L) | 30±15.8 | 43.5±10.4 | ns | ||||
| QMVC (N) | 366.6±84.8 | A | 323.3±81 | A | 202.2±51.8 | B | <0.005 |
| 6MWD (m) | 523.8±120.1 | A | 411±158.4 | B | 327±134.1 | B | <0.01 |
| Exacerbation | 1.8±1.5 | A | 4±2.2 | B | <0.05 | ||
| BODE index | 4±2.7 | A | 6.2±2.3 | A | ns | ||
| SGRQ symptoms | 60.1±13.4 | A | 78.3±15.2 | B | <0.05 | ||
| SGRQ activity | 52.1±29.2 | A | 86.2±13.4 | B | <0.005 | ||
| SGRQ impact | 33±24.4 | A | 59.5±20.8 | B | <0.05 | ||
| SGRQ total | 43.5±21.7 | A | 70.7±16.4 | B | <0.01 | ||
| Type I fiber (%) | 38.5±11 | A | 23.9±9.3 | B | 24.7±13.5 | B | <0.05 |
| Type II area (μ2) | 2,564±783.8 | AB | 2,978±785.9 | A | 2,034±498.8 | B | <0.05 |
Notes: Physical activity (V): Voorrips questionnaire; physical activity (L): London Chest Activity of Daily Living Scale. Comparisons among groups were performed using ANOVA and Student–Newman–Keuls as a post hoc test. Diff among the three different groups are stated using letters A, B and C, where sharing a letter implies no differences between these groups and having a different letter implies a statistical difference in the post hoc test.
Abbreviations: 6MWD, 6-minute walking distance; ANOVA, analysis of variance; BMI, body mass index; BODE index, Body-mass index, airflow Obstruction, Dyspnea, and Exercise; COPDL, COPD patients with low FFMI; COPDN, COPD patients with normal FFMI; Diff, differences; FEV1, forced expiratory volume in 1 second; FFM, fat-free mass; FFMI, fat-free mass index; FVC, forced vital capacity; mMRC, modified Medical Research Council; ns, not significant; PaCO2, arterial carbon dioxide partial pressure; PaO2, arterial oxygen partial pressure; QMVC, quadriceps maximal voluntary contraction; SGRQ, St George’s Respiratory Questionnaire.