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. 2021 Nov 8;126(2):204–210. doi: 10.1038/s41416-021-01613-5

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© The Author(s) 2021

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Fig. 1 — Illustration of the three different approaches, dots represent enrolled participants; green periods represent when the arm is open, red when the endpoint is being followed-up and blue the time it takes to conduct the interim analysis. For the colour figure, please see the online version.