David Laursen

David Laursen

@davidlaursen.bsky.social

Clinical trial methodology, systematic reviews, placebo, blinding

196 Followers 996 Following 48 Posts Joined Jan 2024
1 week ago

Thomas Wakley, the original editor of @thelancet.com was indeed no friend of Dr John Snow.
In happier news, the journal published a 'corrected' obituary in 2013:
www.thelancet.com/journals/lan...

We're glad you had a refreshing visit to the John Snow pub @pwgtennant.bsky.social‬ 😊

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2 weeks ago
Preview
a cat wearing sunglasses and a chain around its neck is sitting on a blue couch . Alt: a cat wearing sunglasses and a shiny chain around its neck is sitting on a blue couch looking fabulous.

Typo in student paper: Single-bling randomized control trial

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1 month ago

@spacecowboybooks.bsky.social Thanks for a very useful feed! Only minor quibble: The feed seems to "refresh" every time I go away from it (to another feed) and back - losing my current "reading progress". Other similar feeds do not appear to refresh as often. Possible to reduce "refresh rate"?

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1 month ago

Thanks, I'll take a closer look!

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1 month ago

Casual causal?

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1 month ago

Causal inference coming to an unblinded trial near you!

Hoping to read it more carefully soon and understand how it relates to previous efforts in measuring and handling unblinding (e.g. blinding indices) and to choice of control (e.g. active placebo)

#Blinding #Masking #Unblinding #Unmasking

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1 month ago

... (in an estimation setting, this would probably be estimating differences in beliefs between arms, either with conventional 2x2 measures, or blinding indices). This appears to be a central discussion in many fields, so would appreciate your reflections.

Thanks in advance!

3/3

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1 month ago

I noticed your warning against conditioning on post-treatment belief (since it is a collider). Just wondering, does this reservation extend more generally to cautioning against testing for success of blinding at all, regardless of doing a stratified analysis of treatment effects by belief? ...

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1 month ago

(cross-posting from Disqus at MedRxiv now that I found this post: hope that's okay!)

Thanks for an interesting preprint, which I hope to read more carefully soon. I am not particularly well versed within causal inference so apologies if the question is unclear.

...

1/3

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2 months ago

Previous post about this study:
bsky.app/profile/davi...

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2 months ago

3 If feasible and meaningful, have another person check procedures that are not done in duplicate (e.g. trial overlap removal).

5/5

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2 months ago

Lessons learned:
1 Use automatic data checks (e.g., that all trials are included in analysis, and no more than once), and ensure that they are working as intended.
2 Add useful extra info the appendix for easy validation (e.g. forest plots for all main analyses with outcomes listed).

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2 months ago

Correcting these mistakes leads to small changes in estimates but does not change our overall conclusions (NB. two analyses of heterogeneity become statistically significant, but we interpret these with caution).

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2 months ago

Some details: One mistake related to incorrect exclusion of a few trials during removal of overlapping trials across meta-analyses). The other mistake was misclassifying a meta-analysis (about attrition but classified as co-intervention) which then entered the wrong analysis.

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2 months ago

Errare humanum est ...
(To err is human ...)

While preparing my PhD thesis, I discovered some (minor) errors in which trials and meta-analyses were included for analysis in our meta-epidemiological study.

1/5

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2 months ago

Sounds great! Would be interesting to compare # original posts across platforms

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2 months ago

Thanks for the status! Do you have separate numbers for original posts vs reposts and how these compare between Bluesky and X?

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3 months ago

Webinar - read more and sign up: www.cochrane.org/events/how-t...

On 17 February 2026, Andreas Lundh and AsbjΓΈrn Hrobjartsson will host a Cochrane Learning Live webinar about the TACIT tool.

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3 months ago

... IN MICE 🐭

jamesheathers.medium.com/in-mice-expl...

Vigtigt med retvisende overskrifter og passende forbehold for ekstrapolering til mennesker.

#JustSaysInMice #InMice #IMus

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4 months ago

Many seemingly overlapping terms: MCID, MID, minimally relevant different (MiReDif), smallest effect size of interest (SESOI), smallest worthwhile difference (SWD) ...

Different traditions? Would be nice with a good overview.

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4 months ago

Thanks, I'll check it out!

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4 months ago

Any specific critical literacy resources from philosophy you would recommend?

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4 months ago

Happening TODAY at 3pm GMT πŸ‘‡

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4 months ago
Preview
Introduction to INSPECT-SR Training Workshop December An introductory 2-hour online workshop will introduce participants to the INSPECT-SR tool for assessing trustworthiness of randomised controlled...

Have increased capacity for this December INSPECT-SR online training workshop following a successful 1st event today. Book here: www.trybooking.com/uk/FKHV

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4 months ago

Recent trial with potential data problems @bmj.com. Great with IPD available for checking.

Helpful/feasible with early standard checks in submission? E.g. onlinelibrary.wiley.com/doi/full/10....) or INSPECT-IPD (in development, www.sciencedirect.com/science/arti..., @jdwilko.bsky.social)

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4 months ago

In Danish, it is similar with the word for male cousin (perhaps more in humorous context). E.g., "I saw this weird cousin in the train today ..."

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4 months ago

@tweis.bsky.social

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4 months ago

Just to clarify our definition: active placebo = similarly looking control + imitating the perceptible side effects of the exp drug + not therapeutic. Agree that standard of care needs to be considered for both/control arm(s), e.g. therapeutically active control.

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4 months ago
Example of a trial sequential analysis plot. From: https://ctu.dk/tsa/

What: Webinar on trial sequential analysis (TSA) in meta-analyses
When: 28 Oct 2025 13:00 to 13:45 (CEST)
Where: syddanskuni.zoom.us/j/61110310530

Christian Gunge Riberholt, associate professor at the University of Copenhagen, will talk about TSA and the potential errors of using it.

#MetaAnalysis

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4 months ago

Ah, OK! Stopping rules are not my field so forgive me if mistaken. I think active placebos would likely not mask true disease progression itself, but potentially affect "subjective" assessments, e.g. chronic pain, depression, PTSD. (But ethics important re. imitated side effects' acceptability)

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