The aim of this thesis was to answer currently unanswered questions regarding health-related quality of life (HRQoL) in glioma patients by undertaking powerful detailed secondary analyses of... Show moreThe aim of this thesis was to answer currently unanswered questions regarding health-related quality of life (HRQoL) in glioma patients by undertaking powerful detailed secondary analyses of existing pooled individual HRQoL patient data, which was previously collected in 15 RCTs in glioma patients.In total, data of 6048 glioma patients was included in the CODAGLIO database and 5 manuscripts were written that provide relevant information both for clinical practice as well as for clinical trials. Results of these studies entailed information on the added prognostic value of HRQoL at baseline in predicting survival. Furthermore, symptom clusters were identified and their association with functioning was investigated, and the impact of both (progression of) the disease and treatment on HRQoL deterioration was studied. Moreover, the ‘net clinical benefit’, weighing HRQoL and survival was calculated and different analytical methods to calculate change in HRQoL were compared.The CODAGLIO project, the largest individual patient data (IPD) project in neuro-oncology research so far, showed to represent an unique opportunity for secondary hypothesis testing, to answer clinically relevant questions with respect to HRQoL. Show less