Brennan Kahan's Avatar

Brennan Kahan

@brennankahan

Principal Research Fellow in Medical Statistics at MRC Clinical Trials Unit at UCL. Clinical trials, estimands, estimation. https://scholar.google.co.uk/citations?user=Lf0jsXAAAAAJ&hl=en&oi=sra

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11.10.2023
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Latest posts by Brennan Kahan @brennankahan

The epistemological trap from the real-world evidence concept. ‘Real-world’ evidence (RWE) and related terms are gaining popularity in scientific literature, usually in reference to evidence collected outside of traditional randomized controlled trials (RCT). How...

The epistemological trap from the real-world evidence concept. - Journal of Clinical Epidemiology www.jclinepi.com/article/S089...

22.02.2026 12:47 👍 7 🔁 3 💬 0 📌 1

*Using Simulation Studies to Evaluate Statistical Methods* by @matteoq21.bsky.social & Tra My Pham (@mrcctu.bsky.social).

🗓️ 19 – 20 & 26 – 27 November 2026
🏢 Online
🌐 t1p.de/simulation_s...

02.03.2026 11:22 👍 2 🔁 2 💬 1 📌 0

As a known HR hater, it brings me no joy to post this but I do think some papers are a bit sloppy with their criticisms of the HR (as highlighted by this nice paper)

Some say the overall HR is not causal. But I don't think this is the case for reasons provided here

11.02.2026 14:39 👍 5 🔁 2 💬 3 📌 0

"An online sample size calculator for designing partially clustered trials" (@klange-au.bsky.social et al) has now been published in Clinical Trials!
doi.org/10.1177/1740...

This free and user-friendly online calculator makes it easier to ensure a trial is appropriately powered ✅

04.02.2026 03:01 👍 5 🔁 3 💬 0 📌 1
Banner for blog post, showing the title and part of the image in the post (with its own alt text in the post).

Banner for blog post, showing the title and part of the image in the post (with its own alt text in the post).

New post on a topic you might have struggled with if you do simulation studies. For a given data-generating mechanism, you might wonder “What is the true value of my estimand?”

This post describes four ways to learn it.
tpmorris.substack.com/p/learning-t...

09.01.2026 13:44 👍 13 🔁 2 💬 2 📌 0
The words 'JOB VACANCY' on the left hand side, and the OCTRU logo on the right hand side, on a white background showing graphs

The words 'JOB VACANCY' on the left hand side, and the OCTRU logo on the right hand side, on a white background showing graphs

New Year, New Job? 📆

If you'd like to contribute to the design, conduct & analysis of research projects (and more!), we are looking for a Medical Statistician to join our team!

Apply by 2nd Feb, 12 noon.

Find out more, and see all of OCTRU's vacancies here: www.ndorms.ox.ac.uk/octru/about-...

05.01.2026 12:41 👍 0 🔁 4 💬 0 📌 1
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Causal inference is hard, and advanced statistical analysis is not enough Health researchers need to fully understand the underlying assumptions to uncover cause and effect. Timothy Feeney and Paul Zivich explain Physicians ask, answer, and interpret myriad causal question...

As an editor I often see authors fall into a trap of stressing some fancy statistical technique for estimating causal effects. Often neglected are the necessary assumptions to map the data to the estimand. @pausalz.bsky.social and I wrote about it here www.bmj.com/content/391/...
#EpiSky

19.12.2025 14:12 👍 15 🔁 6 💬 1 📌 0
Estimands: what they are and why we should use them In clinical trials, postrandomization events, such as treatment discontinuation or the use of rescue medication, can complicate the interpretation of results. An estimand is a precise description of t...

New paper in @jclinepi.bsky.social: **Estimands: what they are and why we should use them**

We provide simple explanations of:
-estimands and intercurrent events
-how these relate to familliar concepts like ITT
-how to write estimands for protocols
-and more

www.jclinepi.com/article/S089...

05.12.2025 13:29 👍 11 🔁 5 💬 0 📌 0
Home - Irish Reproducibility Network My WordPress Blog

Just a reminder about the new all-island Irish Reproducibility Network. There are already lots of great people involved. You can sign up and find local site leads with the link, and if you are based in Cork feel free to reach out to me directly.

irishrn.org

05.12.2025 10:54 👍 9 🔁 6 💬 0 📌 0
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NEW PAPER: "Reporting guidelines for studies involving generative artificial intelligence applications: what do I use, and when?"

--> www.nature.com/articles/s41...

#HealthTech #ClinicalAI #MachineLearning #MedAI #AIinMedicine #TransparentAI #HealthInnovation #GenAI

07.11.2025 12:44 👍 13 🔁 8 💬 0 📌 0

The term #estimand is now part of the technical language of trials - but it remains a concept that many find hard to understand. Recent work has aimed to make the term more accessible to researchers, patients & public 1/8
#MethodologyMonday #127

03.11.2025 07:44 👍 17 🔁 8 💬 1 📌 1
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NEW paper "Clinical prediction models using machine learning in oncology: challenges and recommendations"

--> tinyurl.com/2h2mcy5h

#machinelearning #prediction #statssky #MLsky #methodsmatter

30.10.2025 08:38 👍 8 🔁 2 💬 0 📌 0
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Supporting public involvement in defining estimands: a practical tool accessibly explaining the five key attributes of an estimand - Trials Background An estimand is a precise description of the treatment effect a trial is aiming to find out. We previously identified that public partners (defined as patients and/or members of the public w...

📢 New publication in #Trials led by @suziecro.bsky.social with the HEALTHY STATS public involvement group: Supporting public involvement in defining estimands: a practical tool accessibly explaining the five key attributes of an estimand trialsjournal.biomedcentral.com/articles/10....

28.10.2025 12:36 👍 4 🔁 3 💬 0 📌 0
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Sage Journals: Discover world-class research Subscription and open access journals from Sage, the world's leading independent academic publisher.

We're excited to share our latest work on estimands in clinical trials!

📄 Estimating treatment effects in trials with outcome data truncated by death: A case study on aligning estimators with estimands.

🔗 Read the full paper: journals.sagepub.com/doi/10.1177/...

27.10.2025 14:42 👍 3 🔁 3 💬 1 📌 0

Want to come work on SNAP, BALANCE+, and STRAP? And change how we treat and manage bloodstream infections? See below. #IDSky

27.10.2025 09:28 👍 9 🔁 5 💬 0 📌 0
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Current Opportunities We have an iCASE studentship available to start for the 2025/2026 academic year, and applications to our fifth round of recruitment to our DTP to start in October 2026 are now also open. Please see…

📢 Interested in a PhD in clinical trials methodology? The Trials Methodology Research Partnership are advertising projects for PhDs starting Oct 2026, in statistics, health economics, epidemiology, social science, and more, hosted at one of 12 UK partner institutions.
mrctmrpdtp.com/current-oppo...

24.10.2025 08:58 👍 12 🔁 13 💬 0 📌 1

📢 As one of the next round of TRMP PhD students (below) you could join me, Clare Robinson, @averoniki.bsky.social and @marionkcampbell.bsky.social to work on developing a typology of research outputs in trials methodology, based at @wiphcem.bsky.social. Details here: www.findaphd.com/phds/project...

24.10.2025 09:03 👍 8 🔁 9 💬 1 📌 0
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Current Opportunities We have an iCASE studentship available to start for the 2025/2026 academic year, and applications to our fifth round of recruitment to our DTP to start in October 2026 are now also open. Please see…

🎓 Thinking about a PhD in clinical trial #methodology?

We have two funded PhD opportunities for students passionate about trial design and statistical methods:

• One in estimands
• One in non-inferiority trials

🔗 More info and how to apply here: buff.ly/lCpqcF6

@mrcnihrtmrp.bsky.social

23.10.2025 09:02 👍 3 🔁 5 💬 0 📌 1
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Optimising the choice of estimand in randomised trials: developing guidance on balancing statistical and clinical considerations to ensure results matter to stakeholders at University College London o... PhD Project - Optimising the choice of estimand in randomised trials: developing guidance on balancing statistical and clinical considerations to ensure results matter to stakeholders at University Co...

New PhD position available at @mrcctu.bsky.social to develop guidance on balancing statistical and clinical considerations when choosing an estimand in RCTs.

www.findaphd.com/phds/project...

22.10.2025 10:45 👍 7 🔁 10 💬 0 📌 0
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The recording of this webinar is now available on the @nihr-rss.bsky.social YouTube channel: www.youtube.com/watch?v=4cNz...

21.10.2025 13:32 👍 11 🔁 11 💬 0 📌 4

Lots of feedback and engagement after this session. Some gentle push-back still: "But what if there's even just a *perception* from sites that a stepped wedge is preferable?" 🧵

21.10.2025 15:39 👍 9 🔁 4 💬 1 📌 0
A scoping review identified additional considerations for defining estimands in cluster randomised trials An estimand is a clear description of the treatment effect a study aims to quantify. The ICH E9(R1) addendum lists five attributes that should be described when defining an estimand. However, the adde...

A scoping review identified additional considerations for defining estimands in cluster randomised trials - Journal of Clinical Epidemiology www.jclinepi.com/article/S089...

19.10.2025 14:33 👍 4 🔁 5 💬 0 📌 0
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Introduction to INSPECT-SR Training Workshop November An introductory 2-hour online workshop will introduce participants to the INSPECT-SR tool for assessing trustworthiness of randomised controlled...

Introductory online INSPECT-SR workshop. November 6th, 12-2pm UK-time. Free, places limited. BOOK: www.trybooking.com/uk/events/la...

03.10.2025 11:08 👍 8 🔁 7 💬 1 📌 1
The number needed to treat: It is time to bow out gracefully The number needed to treat (NNT) has statistical and methodological limitations that make it unhelpful in the context of developing clinical practice guidelines and policy decisions.It is not unusual ...

The number needed to treat: It is time to bow out gracefully - Journal of Clinical Epidemiology www.jclinepi.com/article/S089...

20.08.2025 13:54 👍 5 🔁 5 💬 0 📌 0

There has been a lot of debate recently about the promise of real world data - the routine (observational) data collected on patients eg  treatments received, clinical outcomes etc – for estimating treatment effects. But can they deliver? 1/9
#MethodologyMonday #123

18.08.2025 06:35 👍 28 🔁 16 💬 2 📌 2
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Grand rounds in methodology: improving the design of staggered implementation cluster randomised trials The stepped-wedge cluster randomised trial is a popular design in implementation and health services research. All clusters, such as clinics or hospitals, start in the control state, and gradually swi...

Improving the design of staggered implementation cluster randomised trials qualitysafety.bmj.com/content/earl...

05.08.2025 12:20 👍 3 🔁 3 💬 0 📌 0

We often now hear the term “Bayesian borrowing” in trials. But what is Bayesian borrowing and what are the pros and cons around its use? 1/6
#MethodologyMonday #122

21.07.2025 07:10 👍 20 🔁 11 💬 1 📌 0
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NEW PAPER in @bmj.com "Dealing with continuous variables and modelling non-linear associations in healthcare data: practical guide"

--> www.bmj.com/content/390/...

#methodologymatters #StatsSky #EpiSky

16.07.2025 11:59 👍 51 🔁 17 💬 1 📌 4

If outcome = "no. of antibiotic prescriptions" and more people in one arm get LT antibiotics (which presumably precludes further prescriptions?), this does seem like a challenge.

Could of course be good reasons for it - does highlight importance of estimands (along with justifications for choice)!

15.07.2025 20:17 👍 0 🔁 0 💬 0 📌 0

Think they've used a treatment policy strategy (ie were interested in the effect of Hiprex vs placebo whether or not people started on suppressive antibiotics later).

I don't know enough about the area to say if this is sensible, but if suppressive antibiotics are part of usual care, it may be?

15.07.2025 14:53 👍 0 🔁 0 💬 1 📌 0