Independent variables | Dependent variables | ||||||||
Modified Borg Dyspnoea Scale | mMRC Dyspnoea Scale | FAMRI SHS Questionnaire | |||||||
Dyspnoea score ≥either leg fatigue or tiredness score | Having mMRC ≥1 | Having any respiratory symptoms | |||||||
N | OR ±SEM (95% CI) | P value | N | OR ±SEM (95% CI) | P value | N | OR ±SEM (95% CI) | P value | |
Exercise capacity | |||||||||
VO2Peak | 236 | 1.284±0.543 (0.562 to 2.977) | 0.554 | 245 | 0.078±0.072 (0.011 to 0.438) | 0.005 | 245 | 0.475±0.204 (0.200 to 1.084) | 0.082 |
WattPeak | 236 | 1.003±0.004 (0.995 to 1.012) | 0.472 | 245 | 0.975±0.008 (0.958 to 0.991) | 0.003 | 245 | 0.998±0.004 (0.989 to 1.006) | 0.618 |
WorkTotal | 235 | 1.001±0.001 (0.999 to 1.002) | 0.376 | 239 | 0.996±0.002 (0.993 to 0.999) | 0.014 | 239 | 0.999±0.001 (0.998 to 1.001) | 0.289 |
Cardiovascular outputs | |||||||||
Peaks | |||||||||
O2-PulsePeak | 236 | 0.992±0.066 (0.871 to 1.130) | 0.905 | 245 | 0.808±0.108 (0.614 to 1.039) | 0.110 | 245 | 0.929±0.061 (0.816 to 1.056) | 0.264 |
HRPeak | 236 | 1.008±0.008 (0.992 to 1.024) | 0.337 | 245 | 0.969±0.013 (0.943 to 0.995) | 0.021 | 245 | 0.990±0.008 (0.975 to 1.006) | 0.233 |
SBPPeak | 223 | 1.009±0.007 (0.994 to 1.023) | 0.251 | 226 | 1.015±0.013 (0.990 to 1.043) | 0.244 | 226 | 0.999±0.007 (0.984 to 1.013) | 0.851 |
DBPPeak | 223 | 1.030±0.015 (1.002 to 1.060) | 0.039 | 226 | 0.969±0.023 (0.925 to 1.015) | 0.181 | 226 | 0.987±0.014 (0.959 to 1.014) | 0.342 |
Slopes | |||||||||
O2-PulseSlope | 235 | 0.266±0.348 (0.02 to 3.423) | 0.311 | 238 | 2.777±5.966 (0.040 to 198.051) | 0.634 | 238 | 0.140±0.185 (0.010 to 1.835) | 0.136 |
HRSlope | 235 | 1.159±0.16 (0.886 to 1.526) | 0.284 | 238 | 1.165±0.279 (0.725 to 1.865) | 0.523 | 238 | 1.111±0.155 (0.845 to 1.463) | 0.451 |
SBPSlope | 224 | 1.068±0.114 (0.867 to 1.32) | 0.535 | 227 | 1.714±0.354 (1.149 to 2.599) | 0.009 | 227 | 1.103±0.118 (0.894 to 1.364) | 0.360 |
DBPSlope | 224 | 1.433±0.294 (0.962 to 2.161) | 0.079 | 227 | 1.539±0.547 (0.761 to 3.092) | 0.225 | 227 | 1.245±0.253 (0.836 to 1.865) | 0.281 |
Pulmonary outputs | |||||||||
RRPeak | 230 | 0.995±0.016 (0.965 to 1.026) | 0.751 | 235 | 0.931±0.030 (0.872 to 0.988) | 0.023 | 235 | 0.966±0.016 (0.934 to 0.996) | 0.031 |
VEPeak | 236 | 1.002±0.010 (0.983 to 1.021) | 0.854 | 245 | 0.931±0.020 (0.891 to 0.968) | <0.001 | 245 | 0.982±0.009 (0.964 to 1.001) | 0.060 |
VTPeak | 234 | 1.437±0.584 (0.651 to 3.225) | 0.371 | 239 | 0.887±0.585 (0.232 to 3.135) | 0.855 | 239 | 1.018±0.403 (0.466 to 2.219) | 0.964 |
VO2AT | 196 | 1.067±0.634 (0.331 to 3.439) | 0.912 | 202 | 0.027±0.033 (0.002 to 0.268) | 0.003 | 202 | 0.542±0.312 (0.172 to 1.667) | 0.287 |
VE/VCO2Peak | 236 | 0.953±0.038 (0.879 to 1.028) | 0.221 | 245 | 0.976±0.073 (0.836 to 1.118) | 0.740 | 245 | 0.939±0.038 (0.864 to 1.015) | 0.126 |
RV/TLC | 228 | 0.977±0.032 (0.915 to 1.042) | 0.478 | 235 | 1.102±0.061 (0.989 to 1.232) | 0.079 | 235 | 1.061±0.035 (0.996 to 1.134) | 0.069 |
FRC/TLC | 217 | 1.024±0.026 (0.974 to 1.078) | 0.364 | 220 | 1.136±0.052 (1.043 to 1.247) | 0.004 | 220 | 1.032±0.026 (0.983 to 1.085) | 0.212 |
SHS exposure | |||||||||
Airline SHS exposure (years) | 232 | 1.009±0.016 (0.978 to 1.042) | 0.560 | 241 | 0.982±0.026 (0.932 to 1.034) | 0.496 | 241 | 1.009±0.015 (0.979 to 1.040) | 0.556 |
Childhood home SHS exposure (Y/N) | 236 | 1.078±0.296 (0.628 to 1.85) | 0.784 | 245 | 1.660±0.777 (0.671 to 4.289) | 0.279 | 245 | 2.048±0.563 (1.201 to 3.530) | 0.009 |
Adult home SHS exposure (Y/N) | 236 | 1.156±0.379 (0.609 to 2.209) | 0.657 | 245 | 1.113±0.554 (0.401 to 2.882) | 0.828 | 245 | 2.048±0.660 (1.094 to 3.884) | 0.026 |
Associations of respiratory symptoms at rest (mMRC Dyspnoea Scale and FAMRI SHS Questionnaire) and during exercise (modified Borg Dyspnoea Scale) (dependent variables) with each of the cardiopulmonary exercise measures and SHS exposure (predictors) were assessed by univariate linear regression models with adjustment for age, sex, height, body mass index and corresponding baseline values (for slope predictors). Statistically significant values are shown in bold.
DBP, diastolic blood pressure; FRC, functional residual capacity; HR, heart rate; O2-PulsePeak, oxygen uptake per heartbeat at peak exercise; RRPeak, peak respiratory rate; RV, residual volume; SBP, systolic blood pressure; SHS, secondhand smoke; TLC, total lung capacity; VCO2Peak, peak carbon dioxide production; VEPeak, peak minute ventilation value; VO2AT, oxygen uptake at Anaerobic Threshold; VO2Peak, peak oxygen uptake; VTPeak, peak tidal volume.