I had the pleasure today to participate in a PSI event on non-proportional hazards and applications in immuno-oncology. Non-proportional hazards are increasingly encountered in clinical trials, and there remain important questions about how to analyse trials when non-proportional hazards could occur. These include questions about how to formulate an appropriate hypothesis test for assessing evidence of benefit of the new treatment over the control and how to best quantify the treatment effect. The talks were really very interesting, and lead me to believe there is still lots of important work to be done in this area.

Here are the slides of my talk in case they are of interest, where I discuss some of the subtleties involved in interpreting changes in hazards and hazard ratios over time, which are complicated by the ubiquitous presence of frailty effects. I’ve posted on this topic previously quite a lot – for those interested see the related posts below.

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- What can we infer from proportional hazards?
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- Testing equality of two survival distributions: log-rank/Cox versus RMST
- Using hazard ratios to estimate causal effects in RCTs
- Interpreting changes in hazard and hazard ratios