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Harvard University Biostatistics Working Paper Series

Non-proportional hazards

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Full-Text Articles in Biostatistics

On Assessing Survival Benefit Of Immunotherapy Using Long-Term Restricted Mean Survival Time, Miki Horiguchi, Lu Tian, Hajime Uno Jan 2022

On Assessing Survival Benefit Of Immunotherapy Using Long-Term Restricted Mean Survival Time, Miki Horiguchi, Lu Tian, Hajime Uno

Harvard University Biostatistics Working Paper Series

The pattern of the difference between two survival curves we often observe in randomized clinical trials for evaluating immunotherapy is not proportional hazards; the treatment effect typically appears several months after the initiation of the treatment (i.e., delayed difference pattern). The commonly used logrank test and hazard ratio estimation approach will be suboptimal concerning testing and estimation for those trials. The long-term restricted mean survival time (LT-RMST) approach is a promising alternative for detecting the treatment effect that potentially appears later in the study. A challenge in employing the LT-RMST approach is that it must specify a lower end of …


Ratio And Difference Of Average Hazard With Survival Weight: New Measures To Quantify Survival Benefit Of New Therapy, Hajime Uno, Miki Horiguchi Sep 2021

Ratio And Difference Of Average Hazard With Survival Weight: New Measures To Quantify Survival Benefit Of New Therapy, Hajime Uno, Miki Horiguchi

Harvard University Biostatistics Working Paper Series

The hazard ratio (HR) has been the most popular measure to quantify the magnitude of treatment effect on time-to-event outcomes in clinical research. However, the HR estimated by Cox's method has several drawbacks. One major issue is that there is no clear interpretation when the proportional hazards (PH) assumption does not hold, because it is affected by study-specific censoring time distribution in non-PH cases. Another major issue is that the lack of a group-specific absolute hazard value in each group obscures the clinical significance of the magnitude of the treatment effect. Given these, we propose average hazard with survival weight …