Table 3. Univariate and multivariate analysis of factors predictive of overall survival.
| Characteristic | Univariate analysis | Multivariate analysis | |||||
|---|---|---|---|---|---|---|---|
| Hazard ratio | 95% confidence interval | P value | Hazard ratio | 95% confidence interval | P value | ||
| Treatment group | |||||||
| IMRT | 1 (reference) | – | – | – | – | – | |
| 3DCRT | 1.050 | 0.937–1.774 | 0.402 | – | – | – | |
| Age (years) | |||||||
| <55 | 1 (reference) | – | – | 1 (reference) | – | – | |
| 55–64 | 1.041 | 0.929–1.166 | 0.490 | 1.130 | 1.007–1.267 | 0.028 | |
| 65+ | 1.916 | 1.731–2.120 | <0.001 | 1.717 | 1.502–1.963 | <0.001 | |
| Sex | |||||||
| Male | 1 (reference) | – | – | 1 (reference) | – | – | |
| Female | 0.638 | 0.585–0.695 | <0.001 | 0.642 | 0.588–0.702 | <0.001 | |
| Race | |||||||
| White | 1 (reference) | – | – | 1 (reference) | – | – | |
| African American | 1.149 | 0.994–1.327 | 0.059 | 0.979 | 0.842–1.138 | 0.787 | |
| Hispanic | 0.641 | 0.499–0.824 | 0.001 | 0.567 | 0.440–0.731 | <0.001 | |
| Other/not recorded | 0.683 | 0.476–0.980 | 0.039 | 0.700 | 0.487–1.004 | 0.053 | |
| T stage | |||||||
| T1 | 1 (reference) | – | – | 1 (reference) | – | – | |
| T2 | 1.749 | 1.522–2.010 | <0.001 | 1.663 | 1.447–1.912 | <0.001 | |
| T3 | 2.908 | 2.513–3.365 | <0.001 | 2.374 | 2.044–2.758 | <0.001 | |
| T4 | 3.410 | 2.869–4.052 | <0.001 | 3.084 | 2.581–3.683 | <0.001 | |
| N stage | |||||||
| N0 | 1 (reference) | – | – | 1 (reference) | – | – | |
| N+ | 1.647 | 1.513–1.792 | <0.001 | 1.501 | 1.373–1.640 | <0.001 | |
| Charlson Deyo score | |||||||
| 0 | 1 (reference) | – | – | 1 (reference) | – | – | |
| 1 | 1.596 | 1.422–1.793 | <0.001 | 1.437 | 1.279–1.615 | <0.001 | |
| 2 | 2.353 | 1.944–2.847 | <0.001 | 2.029 | 1.673–2.460 | <0.001 | |
| ≥3 | 2.053 | 1.712–2.461 | <0.001 | 1.815 | 1.498–2.200 | <0.001 | |
| Facility type | |||||||
| Non-academic | 1 (reference) | – | – | 1 (reference) | – | – | |
| Academic | 0.898 | 0.820–0.983 | 0.020 | 0.868 | 0.791–0.953 | 0.003 | |
| Income | |||||||
| ≤$62,999 | 1 (reference) | – | – | 1 (reference) | – | – | |
| $63,000+ | 0.756 | 0.687–0.833 | <0.001 | 0.886 | 0.801–0.981 | 0.019 | |
| Not recorded | 2.295 | 1.460–3.608 | <0.001 | 2.734 | 1.627–4.594 | <0.001 | |
| Residence | |||||||
| Urban | 1 (reference) | – | – | 1 (reference) | – | – | |
| Metropolitan | 1.079 | 0.958–1.214 | 0.211 | 1.008 | 0.892–1.139 | 0.901 | |
| Rural | 1.350 | 1.004–1.814 | 0.047 | 1.173 | 0.870–1.581 | 0.296 | |
| Other/not recorded | 1.029 | 0.763–1.388 | 0.851 | 0.822 | 0.583–1.157 | 0.261 | |
| Insurance | |||||||
| Medicaid | 1 (reference) | – | – | 1 (reference) | – | – | |
| Medicare | 1.179 | 1.019–1.364 | 0.027 | 0.914 | 0.772–1.083 | 0.300 | |
| Private | 0.498 | 0.427–0.580 | <0.001 | 0.583 | 0.498–0.682 | <0.001 | |
| Uninsured | 0.930 | 0.749–1.155 | 0.513 | 0.891 | 0.717–1.108 | 0.300 | |
| Government/other | 0.666 | 0.503–0.884 | 0.005 | 0.640 | 0.481–0.852 | 0.002 | |
IMRT, intensity-modulated radiotherapy; 3DCRT, three-dimensional conformal radiotherapy.