Stratification with predictive factors for clinical trials with time-to-event endpoint

Music City Center 

In clinical trials setting, stratified randomization is frequently employed to mitigate imbalances between treatment groups related to specific factors. Such stratification variables are applied in the analyses to enhance analytical efficiency. For time-to-event endpoints, stratified Cox model is often used for analysis, which assumes a uniform treatment effect across all strata. However, the presence of predictive factors in stratified randomization and analysis, a situation that is not uncommon in real-world settings, can violate this assumption. To evaluate the impact of incorporating predictive factors in stratified analysis, the power of stratified analyses and unstratified analyses are compared. Furthermore, different methods of strata combination for stratified analysis in the context of including predictive factors are also explored and compared to address scenarios where certain strata exhibit very small event counts.

Stratification

Stratified analysis

Predictive factors

Time-to-event 

Biopharmaceutical Section