Medical data Patients' demographics and information regarding their diagnosis and treatment, such as primary conditions, pre-existing co-morbidity, disease severity, sepsis, (re)admission, length of mechanical ventilation, length of ICU stay, delirium (CAM-ICU), pain (CPOT), expected mortality (based on the APACHE II, SAPS II, MPM II and APACHE III-IV models and medication, will be extracted from their medical record and the Dutch National Intensive Care Evaluation (NICE) registry.