To examine the evolution of health care integration strategies and associated conceptualization and practice through a review and synthesis of over 25 years of international academic research and literature.

A search of the health sciences literature was conducted using PubMed and EMBASE. A total of 114 articles were identified for inclusion and thematically analyzed using a strategy content model for systems-level integration.

Six major, inter-related shifts in integration strategies were identified: (1) from a focus on horizontal integration to an emphasis on vertical integration; (2) from acute care and institution-centered models of integration to a broader focus on community-based health and social services; (3) from economic arguments for integration to an emphasis on improving quality of care and creating value; (4) from evaluations of integration using an organizational perspective to an emerging interest in patient-centered measures; (5) from a focus on modifying organizational and environmental structures to an emphasis on changing ways of working and influencing underlying cultural attitudes and norms; and (6) from integration for all patients within defined regions to a strategic focus on integrating care for specific populations. We propose that underlying many of these shifts is a growing recognition of the value of understanding health care delivery and integration as processes situated in Complex-Adaptive Systems (CAS).

This review builds a descriptive framework against which to assess, compare, and track integration strategies over time.