Table 2.
Characteristics of patients in the study group compared with excluded patients.
| Group of patients | Study group | Excluded | P level |
|---|---|---|---|
| N | 423 | 73 | — |
| Females, % | 61.0 | 70.0 | 0.15 |
| Age, years | 68.9 (9.3) | 70.5 (10.2) | 0.18 |
| Pack years | 40.6 (20.8) | 44.7 (23.3) | 0.13 |
| Current smoking, % | 26.8 | 20.5 | 0.26 |
| Heart disease, % | 46.8 | 45.2 | 0.80 |
| Education, years | 8.8 (2.5) | 9.2 (2.7) | 0.25 |
| Lived alone, % | 54.3 | 60.3 | 0.34 |
| Examined in the winter period, % | 75.1 | 77.0 | 0.76 |
| FEV1, % predicted | 37.7 (13.8) | 38.9 (14.9) | 0.55 |
| Prednisolone treatment, % | 3.1 | 6.8 | 0.11 |
| Long-term oxygen therapy, % | 5.0 | 6.8 | 0.51 |
| Oxygen saturation at rest, % | 94.5 (2.1) | 94.4 (2.0) | 0.64 |
| Oxygen desaturation during SWT > 4%, % | 218 (51.5) | 32 (43.8) | 0.22 |
| SWT, metre | 184.5 (95.7) | 180.5 (92.9) | 0.74 |
| MRC dyspnoea score | 4.0 (0.9) | 3.8 (1.0) | 0.05 |
| BMI, kg/m2 | 26.0 (6.0) | 26.0 (6.5) | 0.99 |
| Admissions to hospital the previous year1,2,3 | 0 (0, 1) | 0 (0, 2.25) | 0.79 |
| Bed days the previous days1,2,3 | 0 (0, 5.25) | 0 (0, 0) | 0.23 |
| i-BODE index, points | 6 (3) | 5.5 (2.2) | 0.26 |
| Vitamin D, nmol/L2 | 51 (29, 70) | — | — |
| CRP, mg/L2 | 6 (4, 10) | — | — |
| Leukocytes, 109/L2 | 8.7 (7.3, 10.5) | — | — |
1Due to exacerbation of COPD.
2Mean (25, 75) percentiles.
3Mann-Whitney U test.
SWT: Shuttle walking test.
MRC: Medical Research Council.
BMI: body mass index.