Table 3. Multivariable Logistic Regression Predicting the Administration of Adjuvant Radiation Therapy.
| Covariate | OR (95% CI) | P value |
|---|---|---|
| Age at diagnosis, y | 0.98 (0.98-0.98) | <.001 |
| Race | ||
| White | 1 [Reference] | |
| Black | 1.11 (1.04-1.18) | .001 |
| Other | 1.11 (1.01-1.23) | .04 |
| Charlson-Deyo Comorbidity Index score | ||
| 0 | 1 [Reference] | |
| 1 | 0.87 (0.82-0.92) | <.001 |
| 2 | 0.90 (0.78-1.03) | .11 |
| ≥3 | 0.96 (0.76-1.23) | .78 |
| Facility type | ||
| Community cancer program | 1 [Reference] | |
| Comprehensive community cancer program | 0.82 (0.75-0.90) | <.001 |
| Academic or research program | 0.57 (0.52-0.62) | <.001 |
| Integrated network cancer program | 0.63 (0.57-0.69) | <.001 |
| Primary payer | ||
| Not insured | 1 [Reference] | |
| Private insurance or managed care | 0.76 (0.65-0.88) | <.001 |
| Medicaid | 1.02 (0.85-1.22) | .84 |
| Medicare | 0.76 (0.65-0.88) | <.001 |
| Other government | 1.09 (0.89-1.33) | .40 |
| Annual median income quartiles in 2000, $US | ||
| <30 000 | 1 [Reference] | |
| 30 000-34 999 | 1.00 (0.92-1.09) | .96 |
| 35 000-45 999 | 1.01 (0.93-1.10) | .80 |
| ≥46 000 | 1.06 (0.97-1.16) | .21 |
| Individuals in the area with no high school degree in 2000, quartiles, % | ||
| ≥29 | 1 [Reference] | |
| 20-28.9 | 1.07 (0.99-1.15) | .11 |
| 14-19.9 | 0.99 (0.91-1.08) | .81 |
| <14 | 0.96 (0.88-1.04) | .32 |
| Distance from facility, miles | 1.00 (1.00-1.00) | <.001 |
| Year of diagnosis | 0.98 (0.97-1.00) | .01 |
| Tumor category | ||
| T2 | 1 [Reference] | |
| T3 | 2.64 (2.38-2.93) | <.001 |
| T4 | 7.01 (6.29-7.82) | <.001 |
| Gleason score | ||
| ≤6 | 1 [Reference] | |
| 7 | 6.36 (6.04-6.71) | <.001 |
| 8-10 | 6.54 (5.25-8.14) | <.001 |
| Lymph node invasion | ||
| Absent | 1 [Reference] | |
| Present | 1.83 (1.72-1.96) | <.001 |
| Surgical margins status | ||
| Negative | 1 [Reference] | |
| Positive | 3.79 (3.63-3.96) | <.001 |
Abbreviation: OR, odds ratio.