Hazard ratio | |||

Regression 1^{#} | Regression 2^{¶} | Regression 3^{+} | |

Age at diagnosis per decade increase | 1.22 (1.11–1.35) | 1.19 (1.08–1.31) | 1.18 (1.07–1.30) |

Connective tissue disease aetiology | 1.70 (1.29–2.24) | 1.66 (1.25–2.20) | 1.64 (1.23–2.18) |

Functional class per 1-class increase | 1.43 (1.20–1.72) | 1.60 (1.34–1.92) | 1.42 (1.17–1.71) |

Right atrial pressure per 5-mmHg increase | 1.30 (1.18–1.44) | ||

Mean pulmonary arterial pressure per
5-mmHg increase | 1.02 (0.97–1.08) | ||

Cardiac index per 1-L·min^{−1}·m^{−2} increase | 0.79 (0.65–0.96) |

Data are presented with 95% confidence intervals in parentheses. Likelihood ratio (LR) analysis was performed

*versus*the model with age, connective tissue disease aetiology and functional class alone. The model with age, connective tissue disease aetiology, functional class and right atrial pressure is the best model. Adding cardiac index does not help discriminate further (LR test for model 1 with cardiac index*versus*model 1 without cardiac index: p = 0.47).^{#}: independent variables: age at diagnosis, connective tissue disease aetiology of PAH, functional class and right atrial pressure (p<0.0001 on LR analysis);^{¶}: independent variables: age at diagnosis, connective tissue disease aetiology of PAH, functional class and mean pulmonary arterial pressure (p = 0.35 on LR analysis);^{+}: independent variables: age at diagnosis, connective tissue disease aetiology of PAH, functional class and cardiac index (p = 0.013 on LR analysis).