Table 1 Independent variables

– Primary diagnosis for admission to the hospital

– Patient history

– Patient age (in years); year of birth

– Gender

– Number of prescribed drugs before hospital admission

– Admission day and time to ICU

– ICU admission source (location/ providers of care)

– Length of total hospital stay (prior to ICU admission) (LOS) (in days)

– Length of ICU stay (in days)

– Outcome in the ICU (discharge, mortality)

– Acute Physiology and Chronic Health Evaluation (APACHE) II

Patient complexity and mortality risk are defined according to the All Patient Refined Diagnosis Related Groups, which is calculated based on patient diagnosis, procedure, and age using a scale of 1 (least complex/lowest risk) to 4 (most complex/highest risk).

– Quality and completeness of the medical records

– Time measures screening process