PhD defence J. (Jordi) de Winkel

Brief summary on the aim of the doctoral thesis:

Despite improvements in the outcomes of patients with aneurysmal subarachnoid hemorrhage (aSAH) about half of aSAH patient do not recover to functional independence. Much research has focused on finding effective therapies for all SAH patients, but less interest has been taken into personalizing treatment. There is a growing understanding that averaged expected outcomes or treatment effects do not apply to the individual patient. The overall hypothesis of this thesis was that we can improve outcomes of aSAH patients by understanding practice variability and using individualized estimates of outcome and treatment effect to shift from one-size-fits-all all policy to individualized decision-making. The specific aims were:

1. To characterize international variations in treatment and organizational aspects of care that could impact outcomes in patients with aSAH.

2. To optimize and individualize outcome prediction for patients with aSAH.
   • To systematically review and meta-analyze early predictors of functional outcome in poor-grade aSAH patients.
   • To externally validate the ARISE prediction models for predicting pre-interventional aneurysmal rerupture within 24 and 72 hours.
   • To illustrate the pitfalls of single-study external validation by conducting a large number of external validations of a prediction model for functional outcome in aSAH patients.

3. To optimize and individualize treatment in patients with aneurysmal subarachnoid hemorrhage.
   • To develop and internal-externally validate a prediction tool to predict benefit of endovascular coiling compared to neurosurgical clip-reconstruction.
   • To develop a decision model to investigate the optimal aneurysm treatment strategy for individual aSAH patients.