| Group mean (SD) (n = 221) | Regression-coefficient (95% CI) (model r2 = 0.55) | p Value | |
| Constant | – | 814.40 (644.70 to 984.10) | <0.001 |
| Age (years) | 63 (10) | −1.24 (−2.52 to 0.47) | 0.059 |
| Sex (F/M) | – | −36.74 (−66.96 to −6.52) | 0.017 |
| BMI (kg/m2) | 24.9 (3.9) | −6.20 (−9.27 to −3.13) | <0.001 |
| FEV1 % predicted (%) | 47.1 (16.8) | −0.77 (−1.84 to 0.30) | 0.160 |
| TLCO % predicted (%) | 50.5 (17.7) | 0.30 (−0.49 to 1.09) | 0.453 |
| RV/TLC ratio (%) | 55.0 (10.0) | −2.12 (−3.75 to −0.49) | 0.011 |
| Resting PaO2 (kPa) | 9.43 (1.36) | 1.45 (−6.99 to 9.89) | 0.735 |
| Wpeak % predicted (%) | 75.8(31.2) | 1.58 (0.91 to 2.26) | <0.001 |
| MRC dyspnoea scale (1–5) | 3(2–4)* | −19.20 (−31.92 to −6.45) | 0.003 |
| SGRQact score (aU) | 65.6(19.6) | −1.04 (1.76 to −0.32) | 0.005 |
| QMVC (kg) | 31.6(9.9) | 2.26 (0.78 to 3.73) | 0.003 |
| Smoke exposure (ex-current) | – | −23.63 (−45.57 to −1.69) | 0.035 |
Multiple linear regression coefficients with accompanying p values, describe the change in SMWT distance (in metres) per unit change in the group/covariable. Significant p values shown in bold. Descriptive variables shown for reference as mean (SD). *Indicates median (interquartile range). BMI, body mass index; QMVC, maximal isometric voluntary contraction strength; SGRQ, St George’s respiratory questionnaire; SMWT, 6-minute walking test; Wpeak, peak incremental cycle exercise capacity.