Sophie Bots: In Situations Where RCTs and Observational Studies Do Not Align, Who Is ‘Right’?
Sophie Bots, Assistant Professor in Pharmacoepidemiology Method at Utrecht University, shared a post on LinkedIn:
“In situations where RCTs and observational studies do not align, who is ‘right’?
This is one of the key challenges of observational epidemiology, which resurfaced when direct oral anticoagulants (DOACs) seemed less effective in observational studies than the RCTs suggested.
In these situations, channelling bias might be at play, where the new medication is prescribed to a (in this case) high-risk subset of patients.
For his MSc thesis, the stellar Raoul van den Hemel visualised patient characteristics of DOAC users and the comparative effectiveness and safety versus warfarin over time to disentangle preferential prescribing effects from those of the medication in the CPRD dataset.
We saw that over time, as DOAC and warfarin users became more similar, the medication’s effects approached RCT findings. So in the end, both were ‘right’.
Interested in the details?
Many thanks to my co-lead Lourens Bloem and co-authors Magdalena Gamba, Patrick Souverein, Olaf Klungel and Aernoud Fiolet for their valuable input and support.”
Title: Comparative treatment effects of direct oral anticoagulants versus warfarin for nonvalvular atrial fibrillation in clinical practice vary over time due to channelling
Authors: Raoul B. L. J. van den Hemel, Aernoud T. L. Fiolet, Magdalena A. Gamba, Patrick C. Souverein, Olaf H. Klungel, Lourens T. Bloem, Sophie H. Bots
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