Table 3.
Multivariable Cox regression models
| Variables | P value | HR | 95% CI |
|---|---|---|---|
| Valproic acid model | |||
| RTOG RPA class | <.001 | 1.49 | 1.37–1.61 |
| Concurrent TMZ | .373 | 0.9 | 0.68–1.12 |
| Seizure history | .136 | 1.17 | 0.96–1.38 |
| Concurrent valproic acid (n=29) | .047 | 0.67 | 0.27–1.07 |
| Phenytoin model | |||
| RTOG RPA class | <.001 | 1.46 | 1.35–1.57 |
| Concurrent TMZ | .04 | 0.81 | 0.63–1.01 |
| Seizure history | .244 | 1.11 | 0.93–1.29 |
| Concurrent phenytoin (n=234) | .267 | 1.11 | 0.93–1.29 |
| Levetiracetam model | |||
| RTOG RPA class | <.001 | 1.53 | 1.42–1.65 |
| Concurrent TMZ | .22 | 0.86 | 0.63–1.10 |
| Seizure history | .543 | 1.06 | 0.87–1.25 |
| Concurrent levetiracetam (n=92) | .549 | 0.92 | 0.65–1.19 |
| Carbamazepine model | |||
| RTOG RPA class | <.001 | 1.46 | 1.35–1.56 |
| Concurrent TMZ | .021 | 0.8 | 0.61–0.99 |
| Seizure history | .225 | 1.12 | 0.94–1.30 |
| Concurrent carbamazepine (n=28) | .757 | 1.07 | 0.66–1.47 |
| Phenobarbital model | |||
| RTOG RPA class | <.001 | 1.45 | 1.34–1.56 |
| Concurrent TMZ | .011 | 0.78 | 0.59–0.97 |
| Seizure history | .192 | 1.13 | 0.95–1.31 |
| Concurrent phenobarbital (n=27) | .26 | 0.79 | 0.37–1.20 |
Abbreviations: CI = confidence interval; HR = hazard ratio; RTOG RPA = Radiation Therapy Oncology Group; TMZ = temozolomide.