Table 2.
Multivariable negative binomial regression assessing the association between patient characteristics and number of surveys completed.
| IRR | 95% CI | p-value | Predicted Number of Surveys | |
|---|---|---|---|---|
| Characteristic | ||||
| Age (per 10 years) | 0.93 | 0.90, 0.95 | <0.001 | 45-year-old: 5.9 65-year-old: 5.1 |
| Race | <0.001 | |||
| Non-white minority | — | — | 4.7 | |
| White, non-Hispanic | 1.17 | 1.09, 1.25 | 5.5 | |
| Education | <0.001 | |||
| High school or less | — | — | 4.2 | |
| College/Vocational school | 1.49 | 1.34, 1.65 | 6.2 | |
| Graduate/Professional School | 1.31 | 1.19, 1.45 | 5.5 | |
| Unknown | 1.05 | 0.94, 1.17 | 4.4 | |
| Work status | 0.001 | |||
| Employed full-time | — | — | 5.5 | |
| Not employed full-time | 0.94 | 0.88, 1.01 | 5.2 | |
| Unknown | 0.84 | 0.76, 0.92 | 4.6 | |
| Treatment group | <0.001 | |||
| Partial-breast irradiation | — | — | 5.3 | |
| Whole-breast irradiation (WBI) | 1.03 | 0.95, 1.13 | 5.5 | |
| WBI with regional nodal irradiation (RNI) | 0.79 | 0.70, 0.91 | 4.2 | |
| Post-mastectomy | 0.95 | 0.85, 1.07 | 5.1 | |
| Chemotherapy | 0.002 | |||
| No | — | — | 5.5 | |
| Yes | 1.11 | 1.04, 1.18 | 6.1 | |
| Clinic Setting | 0.6 | |||
| Regional | — | — | 5.5 | |
| Main | 1.02 | 0.95, 1.09 | 5.6 | |
| Distance to clinic (per 50 miles) | 1.01 | 1.01, 1.02 | <0.001 | 5 miles: 5.5 100 miles: 5.6 |
| SES (ADI, per 10 units) | 1.02 | 1.00, 1.03 | 0.007 | 5 units: 5.4 20 units: 5.6 |
The IRR is the incidence rate ratio and corresponds to the ratio of the number of surveys completed. For illustrative purposes, we show the predicted num ber of surveys for different groups holding other predictors at the mean.