Table 4. Multivariable Analysis of Risk Factors for Disease-Specific Mortality.
| Variable | Hazard Ratio (95% CI) | P Value |
|---|---|---|
| Older age, per decade | 1.36 (1.17-1.59) | <.001 |
| Socioeconomic status | ||
| Lowest | 1 [Reference] | NA |
| Lower middle to middle | 1.20 (0.61-2.34) | .60 |
| Higher middle to highest | 0.51 (0.25-1.05) | .07 |
| Charlson Comorbidity Index ≥1 vs 0 | 1.55 (0.96-2.48) | .07 |
| Hospital type | ||
| Private | 1 [Reference] | NA |
| Public | 0.86 (0.33-2.28) | .77 |
| Academic | 0.66 (0.33-1.33) | .25 |
| Health maintenance organization | 1.77 (1.04-3.03) | .04 |
| Tumor size, cm | ||
| 0 to 1 | 1 [Reference] | NA |
| >1 to 2 | 1.84 (0.61-5.53) | .28 |
| >2 to 4 | 2.83 (1.08-7.44) | .03 |
| >4 | 2.89 (1.09-7.71) | .03 |
| Lymph nodes examined, No. | 0.98 (0.97-1.00) | .01 |
| Radiotherapy | ||
| None | 1 [Reference] | NA |
| External beam radiotherapy | 2.14 (1.23-3.71) | .007 |
| Radioactive iodine | 1.34 (0.41-4.39) | .63 |
| Other | 3.95 (1.22-12.85) | .02 |
| Stage | ||
| Localized | 1 [Reference] | NA |
| Regional | 4.77 (2.29-9.94) | <.001 |
| Metastatic | 21.08 (9.90-44.89) | <.001 |
Abbreviation: NA, not applicable.