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An improvement in the method used to assess discriminatory ability when predicting the chances of a live birth after one or more complete cycles of in vitro fertilisation

BMJ 2018; 362 doi: https://doi.org/10.1136/bmj.k3598 (Published 05 September 2018) Cite this as: BMJ 2018;362:k3598
  1. David J McLernon, research fellow in medical statistics1,
  2. Ewout W Steyerberg, professor of medical decision making2,
  3. Egbert R te Velde, emeritus professor of reproductive medicine2,
  4. Amanda J Lee, professor of medical statistics3,
  5. Siladitya Bhattacharya, professor of reproductive medicine and director3
  1. 1Medical Statistics Team, Institute of Applied Health Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
  2. 2Department of Public Health, Erasmus MC-University Medical Centre Rotterdam, 3000 CA Rotterdam, The Netherlands
  3. 3Institute of Applied Health Sciences, Polwarth Building, University of Aberdeen, Aberdeen, AB25 2ZD, UK
  1. d.mclernon{at}abdn.ac.uk

Summary

Our paper presents two clinical prediction models that estimate the chance of having a baby over multiple complete cycles of in vitro fertilisation (IVF)—that is, cumulative live birth.1 The pretreatment model predicts the chance of cumulative live birth before treatment starts, and the post-treatment model predicts the chance of cumulative live birth just after the first embryo transfer. Through a collaboration with researchers from the University of Utrecht, who have externally validated these models, we have decided to revise the method used to assess the discriminatory ability of our models in the original study. In time to event models, such as ours, discrimination indicates the proportion of all pairs of women who can be ordered such that the woman with the lower predicted chance of live birth is the one who either did not have a live birth or had more complete cycles of IVF to have a live …

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