Ross 14et al. [] mean (r=0.82) | p-value | Ross 14et al. [] (r=0.59) | p-value | Miyamoto 16et al. [] (r=0.68) | p-value | Zapico 17et al. [] (R^{2}=0.48) | p-value | New model (R^{2}=0.48) | p-value | |

Observations n | 1038 | 1083 | 27 | 82 | 194 | |||||

Intercept | 4.948 | 4.682 | 4.213 | −21.626 | 1.83 | 0.248 | ||||

6MWD, m | 0.023 | 0.025 | 0.026 | 0.026 | <0.001 | 0.031 | <0.001 | |||

Sex | 4.103 | 0.002 | ||||||||

Height, cm | 0.174 | 0.043 | ||||||||

Weight, kg | −0.071 | 0.02 | −0.023 | 0.22 | ||||||

HRR, bpm | −0.015 | 0.047 | ||||||||

Applied to testing dataset | | | | | | | ||||

SEE, mL/min/kg | 3.03 | 3.22 | 4.36 | 3.08 | ||||||

SEE% mean | 19% | 20% | 27% | 19% | ||||||

Ability to classify to low risk (V′_{O2}_{max} >15 mL/min/kg) | | | | | | | ||||

Sensitivity | 0.96 | 0.96 | 0.91 | 0.69 | ||||||

Specificity | 0.23 | 0.23 | 0.22 | 0.78 | ||||||

PPV | 0.63 | 0.63 | 0.63 | 0.82 | ||||||

NPV | 0.80 | 0.80 | 0.64 | 0.64 |

r from correlation between maxima oxygen uptake (*V*′_{O2}_{max}) and 6-min walk distance (6MWD); R^{2} from linear regression of *V*′_{O2}_{max} against 6MWD. HRR: heart rate response in 6-min walk test (heart rate at maximal exercise – heart rate at rest); NPV: negative predictive value; PPV: positive predictive value; SEE: standard error of the estimate; SEE% mean: SEE as percentage of mean peak oxygen uptake. All coefficients, p-values and R^{2} for Ross *et al*. [14], Miyamoto *et al*. [16] and Zapico *et al*. [17] are copied from the original publications.