Finite-sample correction for the covariate-adjusted log-rank test
In small-sample settings, covariate-adjusted log-rank tests are prone to inflated Type I error rates due to treatment allocation imbalance or a relatively large number of covariates. To address this issue, this work proposes a finite-sample correction method that explicitly accounts for the loss of residual degrees of freedom and the uncertainty in regression coefficient estimation by adjusting the denominator of the test statistic. This approach introduces, for the first time in covariate-adjusted log-rank testing, a correction mechanism that jointly incorporates both degrees-of-freedom reduction and parameter estimation uncertainty. Monte Carlo simulations demonstrate that the proposed correction substantially reduces Type I error rates across a range of scenarios, thereby enhancing the reliability of hypothesis testing in small samples.