Clinical characteristics of study subjects
| Condition | Control | COPD | Significance of difference, p value |
|---|---|---|---|
| Number | 25 | 103 | |
| M (F) | 14 (11) | 67 (36) | 0.4888 (F) |
| Age | 67.04 (8.1) | 66.47 (8.4) | 0.757 (T) |
| Height (cm) | 168 (8.9) | 168 (8.6) | 0.886 (T) |
| Weight (kg)* | 69.1 (83.5, 62) | 68.8 (80.6, 59.5) | 0.359 (MW) |
| BMI (kg/m2)* | 24.8 (27.05, 24) | 24.1 (27, 21.4) | 0.134 (MW) |
| FFMI (kg/m2)* | 16.4 (19.8, 15.2) | 15.7 (17.2, 14.5) | 0.060 (MW) |
| Pack year smoking* | 0 (8.75, 0) | 45 (60.6, 34) | <0.001 (MW) |
| FEV1 (% pred)* | 110 (114, 101) | 42 (57, 27) | <0.001 (MW) |
| RV/TLC (%) | 37 (4.8) | 57 (9.2) | <0.001 (T) |
| TLCO (% pred) | 91 (14.2) | 43 (17.6) | <0.001 (T) |
| PaCO2 (kPa) | 5.28 (0.4) | 5.14 (0.6) | 0.337 (T) |
| PaO2 (kPa) | 11.0 (1.2) | 9.31 (1.3) | <0.001 (T) |
| 6MWD (m) | 614 (83) | 394 (120). | <0.001 (T) |
| SGRQ* | 2 (7.5, 0) | 54 (64, 43) | <0.001 (MW) |
| Best MVC (kg) | 35.8 (10.2) | 29.5 (10.2) | 0.006 (T) |
| Best TwQ (kg)* | 8.6 (11.4, 7.0) | 7.6 (9.2, 6) | 0.081 (MW) |
| MVC/wt (kg/kg)* | 0.49 (0.38, 0.57) | 0.41 (0.37, 0.51) | 0.014 (MW) |
| MHCI mRNA (AU)* | 32 (48, 20) | 7.3 (14.5, 4.6) | <0.001 (MW) |
| MHCIIa mRNA (AU)* | 1.6 (2.3, 0.9) | 2.5 (3.8, 1.5) | 0.045 (MW) |
| MHCIIx mRNA (AU)* | 5.2 (8.1, 4.2) | 11.4 (19.3,8.0) | <0.001 (MW) |
Values are mean (SD) for normally distributed data or median (75th, 25th percentile) for non-normally distributed data in patients with COPD or healthy controls (indicated by*). p Values were calculated by t test (normally distributed data, T), Mann–Whitney test (non-normally distributed data, MW) or Fischer's exact test (F) and are shown in bold when p<0.05. MHC RNAs were determined by quantitative PCR and normalised to the expression of RPLPO in the same samples as described in the online supplement.
6MWD, 6 min walk distance; BMI, body mass index; COPD, chronic obstructive pulmonary disease; CSA, cross-sectional area; FEV1, forced expiratory volume in 1 s; FFMI, fat-free mass index; MHC, myosin heavy chain; MVC, maximal voluntary contraction; PaCO2, arterial carbon dioxide tension; PaO2, arterial oxygen tension; pred, predicted; RV, residual volume; SGRQ, St George's Respiratory Questionnaire; TLC, total lung capacity; TLCO, transfer factor of the lung for carbon monoxide; TwQ, twitch force in the quadriceps.