“…Studies targeting specific vulnerable or special-service populations-namely, homeless young adults, young veterans, and chronic illness or disability groups-were excluded due to their different treatment needs (37,38). Consistent with existing research (39,40), mental health services were broadly defined as community mental health services, counseling services, or services provided in hospital departments, with treatment delivered by trained mental health professionals (that is, general practitioners, nurses, psychiatrists, psychologists, psychotherapists, counselors, or social workers), regardless of duration of service use or data collection method (that is, prospectively via self-report or retrospectively via medical records). Eligible studies were published in English in a peer-reviewed journal between January 1990 and June 2015.…”