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Kaspar Rufibach Profile picture
Kaspar Rufibach
@numbersman77
Family & sports person. Biostatistician for @roche in @BaselStadt. @numbersman77@mstdn.science
Jan 26, 2023 • 10 tweets • 4 min read
Ever planned RCT w/ PFS and OS as formal endpoints?

Ever simulated PFS and OS for same set of patients?

In both cases: How did you model the fact that PFS and OS are highly dependent? E.g. we know that PFS <= OS and P(PFS = OS) > 0.

A (long) thread - but it' s worth it!

1/n We are very used to model dependency of an endpoint over time (= group-sequential designs) or over nested populations (= enrichment designs), b/c then it's not difficult to write down correlation between test statistics.

However, typically in trial planning PFS and OS...

2/n
Mar 10, 2021 • 12 tweets • 5 min read
1/n

Stop the abuse: plea for more principled approach to analysis of AEs.

A (long) thread. Please RT.

@tim_friede @ADAlthousePhD @VR_Cornelius @RachPips @statsepi

How are AEs typically reported in an RCT? Along the lines of the table below.

From: nejm.org/doi/full/10.10… 2/n

So what is the purpose of such tables? I see two:

1) "Signal detection" --> find AEs that differ between arms.

2) Estimate true probability of an AE of interest, P(AE).

I will focus on 2) below.
Mar 10, 2021 • 4 tweets • 2 min read
1/n

Clinical trials in patients with hematological malignancies often present unique challenges for trial design due to complexity of tmt options and existence of potential curative but highly risky procedures, for example, SCT or tmt sequence across different phases. 2/n

I am very happy to see our paper

Estimands in hematologic oncology trials

now online at Pharm Stat: doi.org/10.1002/pst.21…

The paper illustrates how to apply the estimand framework in hematological clinical trials and how the estimand framework can address...
Nov 11, 2020 • 20 tweets • 6 min read
1) Why do we run group-sequential trials in drug development?

2) How does the effect we power at relate to the effect(s) needed to stop?

3) Is stopping such a trial early (like the one for the Pfizer vaccine) "cheating"? 4) If stopping early the effect estimate may be biased. Is this an issue?

5) What happens operationally if a trial stops early?
Nov 9, 2020 • 11 tweets • 4 min read
1/n I was asked to give an industry statistician's view on A) below. Disclaimer: I do not know about the exact regulations (which might also be region-specific). What I offer is a 1st hand experience of what happens around a trial stopping early. A thread. 2/n @ADAlthousePhD @MaartenvSmeden @KertViele @raj_mehta @doublerobust