TABLE IV.
Multivariable Cox Regression Hazards Model Evaluating the Association Between Covariates and the Risk of Overall Mortality in Patients Who Traveled a Short Distance to a Low-Volume Facility or a Long Distance to a High-Volume Facility
| Covariate | Adjusted HR* | P Value |
|---|---|---|
| Age | ||
| <18 years | Reference | |
| ≥18 years | 1.91 (1.53 to 2.38) | <0.001 |
| Sex | ||
| Male | Reference | |
| Female | 0.93 (0.82 to 1.05) | 0.251 |
| Race | ||
| White | Reference | |
| Hispanic | 0.67 (0.53 to 0.86) | 0.001 |
| Black | 0.60 (0.45 to 0.79) | <0.001 |
| Asian | 0.61 (0.38 to 0.96) | 0.034 |
| Other | 0.67 (0.41 to 1.12) | 0.127 |
| Modified Charlson-Deyo Comorbidity Index score | ||
| 0 | Reference | |
| ≥1 | 1.26 (1.08 to 1.45) | 0.002 |
| Stage | ||
| I | Reference | |
| II | 2.28 (1.91 to 2.72) | <0.001 |
| III | 2.49 (1.68 to 3.69) | <0.001 |
| IV | 6.71 (5.63 to 8.01) | <0.001 |
| Diagnosis | ||
| Osteosarcoma | Reference | |
| Ewing sarcoma or primitive neuroectodermal tumor | 0.91 (0.74 to 1.13) | 0.389 |
| Chondrosarcoma | 0.68 (0.57 to 0.82) | <0.001 |
| Others | 0.79 (0.66 to 0.94) | 0.009 |
| Insurance status | ||
| Private | Reference | |
| Medicare | 2.69 (2.31 to 3.13) | <0.001 |
| Medicaid | 1.25 (1.02 to 1.54) | 0.031 |
| Other government | 1.32 (0.84 to 2.06) | 0.227 |
| Uninsured | 0.92 (0.64 to 1.32) | 0.647 |
| ZIP Code-level income | ||
| >$63,000 | Reference | |
| $48,000 to $63,000 | 0.83 (0.68 to 1.01) | 0.061 |
| $38,000 to $47,999 | 0.84 (0.68 to 1.04) | 0.101 |
| <$38,000 | 0.90 (0.70 to 1.15) | 0.406 |
| ZIP Code-level lack of high-school education | ||
| <7% | Reference | |
| 7.0% to 12.9% | 1.02 (0.85 to 1.23) | 0.795 |
| 13.0% to 20.9% | 1.11 (0.89 to 1.38) | 0.361 |
| ≥21% | 1.06 (0.81 to 1.38) | 0.665 |
| Rurality | ||
| Rural | Reference | |
| Suburban | 1.04 (0.86 to 1.25) | 0.681 |
| Metropolitan | 0.91 (0.55 to 1.50) | 0.714 |
| Facility location | ||
| Pacific | Reference | |
| Mountain | 0.97 (0.72 to 1.32) | 0.861 |
| West North Central | 1.06 (0.84 to 1.36) | 0.615 |
| East North Central | 0.92 (0.73 to 1.15) | 0.450 |
| Middle Atlantic | 0.85 (0.67 to 1.08) | 0.191 |
| New England | 1.21 (0.89 to 1.64) | 0.232 |
| West South Central | 1.08 (0.77 to 1.52) | 0.655 |
| East South Central | 0.89 (0.69 to 1.16) | 0.395 |
| South Atlantic | 0.88 (0.71 to 1.10) | 0.252 |
| Travel distance per facility volume | ||
| Short distance and low volume | Reference | |
| Long distance and high volume | 0.65 (0.56 to 0.77) | <0.001 |
*
The values are given as the adjusted HR, with the 95% CI in parentheses.