The area of evidence is complex because the best evidence is always for the narrowest, best controllable programs, meaning there is much better evidence about patient outcomes for the treatment of individual diagnoses than for the effectiveness of comprehensive programs that treat many conditions and diagnoses. You cannot assess claims of evidence, no matter how rigorously derived, without a conversation about the larger context of care delivery in the real world.
For integrated primary care, the best “evidence factory” in the US is the University of Washington. Wayne Katon’s team published the watershed paper in integrated care for depression in the Journal of the American Medical Association in 1995. (Katon, W., von Korff, M., Lin, E., Walker, E., Simon, G., Bush, T., Robinson, P., Russo, J. (1995). Collaborative management to achieve treatment guidelines: Impact on depression in primary care. JAMA, 273, 1026-1031.)
The current program from U.W., refined and now being implemented in sites across the country, is the IMPACT program