Tertiary mental health services: II. Subpopulations and best practices for service delivery.

Tertiary care subpopulations are characterized by having more than one significant condition, each of which has been traditionally dealt with by different systems of care. They experience severe and persistent mental illness and one or more of the following: age-related physical or medical conditions, substance use disorders, developmental handicaps, and acquired brain injury. This paper provides estimates of prevalence for each of these subgroups and discusses best practices which have developed in response to their special needs.