Table 1.
Baseline characteristics of subjects
| Demographic characteristics | All subjects | Completed 3 months of PR
|
Groups according to 6MWDi and ∆6MWD
|
P-value | |||||
|---|---|---|---|---|---|---|---|---|---|
| Yes | No | P-value | 6MWDi ≥350 m
|
6MWDi <350 m
|
|||||
| ∆≥30 m; Group 1 | ∆<30 m; Group 2 | ∆≥30 m; Group 3 | ∆<30 m; Group 4 | ||||||
| Number of patients | 423 | 333 | 90 | 125 | 144 | 74 | 80 | ||
| Age (years) | 65±8 | 66±8 | 65±8 | 0.7118 | 65±8 | 65±8 | 67±8 | 67±8 | 0.2380 |
| Male sex, n (%) | 335 (79) | 265 (80) | 70 (78) | 0.7087 | 97 (77) | 115 (80) | 60 (81) | 63 (79) | 0.9400 |
| BMI (kg·m−2) | 25±6 | 25±5 | 25±7 | 0.7913 | 26±5 | 26±5 | 24±6 | 25±6 | 0.5474 |
| Lung function | |||||||||
| FEV1 (% predicted) | 43±16 | 43±15 | 44±19 | 0.8367 | 46±16 | 47±16 | 37±12*,† | 37±16*,† | <0.0001 |
| FEV1/FVC (%) | 41±12 | 40±11 | 43±15 | 0.1643 | 42±11 | 42±11 | 37±11*,† | 39±15 | 0.0066 |
| FRC (% predicted) | 154±37 | 154±37 | 152±38 | 0.5906 | 152±35 | 150±34 | 166±40*,† | 153±39 | 0.0275 |
| DLCO (% predicted) | 48±17 | 48±18 | 48±18 | 0.8556 | 53±17 | 52±17 | 41±13*,† | 40±17*,† | <0.0001 |
| Peripheral muscle force | |||||||||
| QF (Nm) | 100±38 | 102±37 | 92±38 | 0.0232 | 113±35 | 110±35 | 79±30*,† | 80±35*,† | <0.0001 |
| QF (% predicted) | 69±26 | 69±23 | 66±36 | 0.4644 | 75±21 | 78±28 | 57±23*,† | 58±25*,† | <0.0001 |
| Exercise capacity | |||||||||
| Oxygen uptake (% predicted) | 48±19 | 49±19 | 44±18 | 0.0245 | 53±18 | 51±18 | 40±18*,† | 42±21*,† | <0.0001 |
| Oxygen uptake (mL·kg·min−1) | 14±4 | 14±4 | 13±4* | 0.0038 | 16±4 | 15±5 | 12±4*,† | 11±3*,† | <0.0001 |
| Max workload (% predicted) | 48±20 | 49±19 | 45±20 | 0.0892 | 55±19 | 53±18 | 37±18*,† | 37±16*,† | <0.0001 |
| 6MWD (m) | 381±134 | 395±129 | 328±138 | <0.0001 | 458±65 | 469±74 | 234±78*,† | 230±84*,† | <0.0001 |
| 6MWD (% predicted) | 59±21 | 61±20 | 52±22 | <0.0001 | 71±10 | 73±11 | 37±13*,† | 37±14*,† | <0.0001 |
| Health-related quality of life | |||||||||
| CRDQ dyspnea (points) | 15±5 | 16±5 | 15±5 | 0.4908 | 16±5 | 16±5 | 14±5* | 15±5 | 0.0161 |
| CRDQ total score | 78±17 | 78±17 | 76±17 | 0.1916 | 81±16 | 79±17 | 74±17* | 73±16* | 0.0026 |
| Comorbidities | |||||||||
| Cardiovascular (n, %) | 313 (74) | 246 (74) | 67 (75) | 0.8535 | 68 (85) | 59 (79) | 94 (66) | 92 (74) | 0.0124 |
| Metabolic (n, %) | 62 (15) | 42 (13) | 20 (23) | 0.0209 | 12 (10) | 17 (12) | 14 (19) | 19 (24) | 0.0225 |
| Musculoskeletal (n, %) | 87 (21) | 71 (22) | 16 (18) | 0.4730 | 23 (19) | 17 (12) | 26 (35) | 21 (26) | 0.0005 |
| Mental health (n, %) | 125 (30) | 94 (28) | 31 (35) | 0.2387 | 35 (28) | 34 (24) | 27 (36) | 29 (36) | 0.1299 |
| Hospital admissions in the first year | |||||||||
| Time to first respiratory hospitalization (days) | 129±97 | 99±88 | 138±99 | 0.0280 | 176±97 | 122±103 | 128±89 | 103±90* | 0.0129 |
| Hospitalizations within PR (n, %) | 72 (17) | 49 (14) | 23 (25) | 0.0152 | 8 (6) | 24 (17) | 16 (22) | 24 (30) | 0.0001 |
| Hospitalizations in the first year (n, %) | 161 (38) | 121 (36) | 40 (44) | 0.1598 | 32 (25) | 48 (33) | 36 (48) | 45 (56) | <0.0001 |
Notes: Data shown as mean ± SD, n (%), or P-value. Group 1: 6MWDi ≥350 m and Δ6MWD ≥30 m; Group 2: 6MWDi ≥350 m and Δ6MWD <30 m; Group 3: 6MWDi <350 m and Δ6MWD ≥30 m; and Group 4: 6MWDi <350 m and Δ6MWD <30 m. P-values of the four groups refer to one-way analysis of variance or Kruskal–Wallis test;
P<0.05 in post hoc test versus 1;
P<0.05 in post hoc test versus 2. Bold font denotes statistical significance (P<0.05).
Abbreviations: 6MWD, 6-minute walk distance; 6MWDi, initial 6MWD; BMI, body mass index; CRDQ, chronic respiratory disease questionnaire; DLco, diffusion capacity for carbon monoxide; FEV1, forced expiratory volume in the first second; FRC, functional residual capacity; FVC, forced vital capacity; max, maximum; PR, pulmonary rehabilitation; QF, quadriceps force; SD, standard deviation.