Table 4.
Multivariable Cox Proportional Hazards Analysis for the Primary End Point of All‐Cause Mortality
| Variable | Hazard Ratio (CI) | Chi‐Square | P Value |
|---|---|---|---|
| Prior XRT exposure | 8.12 (4.26–15.64) | 44.7 | <0.001 |
| STS score (for every 1% increase) | 1.14 (1.03–1.26) | 7.0 | 0.008 |
| Abnormal vs normal LV‐SVI | 1.33 (0.86–2.04) | 1.72 | 0.19 |
| FEV1 (for every unit decrease) | 1.01 (0.99–1.03) | 1.2 | 0.28 |
| Extent of cardiac surgery | |||
| Isolated AVR | Reference | ||
| AVR+CABG | 1.71 (0.94–3.11) | 3.2 | 0.07 |
| AVR+aorta | 1.13 (0.70–1.84) | 0.19 | 0.65 |
| Persistent postoperative atrial fibrillation | 1.22 (0.76–1.95) | 0.70 | 0.40 |
| Chi‐square for the overall model was 110 (P<0.001) | |||
The model does not account for matching. Please see text for results from the matched model. Predictors that constitute the Society of Thoracic Surgeons (STS) score were not individually entered into the analysis. When forced vital capacity (FVC) or forced expiratory volume at 1 second (FEV1)/FVC ratio were entered instead of FEV1, the results were similar. Due to collinearity between the Charlson comorbidity index and STS score, only the STS score was entered. Results were similar if the Charlson comorbidity index was entered instead of the STS score. AVR indicates aortic valve replacement; CABG, coronary artery bypass grafting; LV‐SVI, left ventricular stroke volume index; XRT, chest radiotherapy.