Findings from the literature review propose a general model based on four categories of determinants 1) patient characteristics: medical history, healthcare knowledge, family support, religion, age/sex/gender/race, residence, type of procedure and severity of disease; 2) clinical caregiver characteristics: culture, specialty, training, team, quality of care and physician choice of prescribed medications; 3) characteristics of the social or family environment: school, peers, political systems, economics and community and 4) characteristics or properties of the healthcare system: admitting service (surgical vs. medical), structure of services, types of services and available technology, palliative care, insurance, long term care, access, setting occupancy, transfers between hospital and care settings venue (emergency vs. non emergency department) and geographic location (urban vs. rural).