Despite policy and practice support to develop and test interventions designed to increase access to quality care among high-need patients, many of these interventions fail to meet expectations once deployed in real-life clinical settings. One example is the Patient-Centered Medical Home (PCMH) model, designed to deliver coordinated care. A meta-analysis of PCMH initiatives found mixed evidence of impacts on service access, quality, and costs. Conceptualizing PCMH as a complex health intervention can generate insights into the mechanisms by which this model achieves its effects. It can also address heterogeneity by distinguishing PCMH core functions (the intervention's basic purposes) from forms (the strategies used to meet each function). We conducted a scoping review to identify core functions and forms documented in published PCMH models from 2007 to 2017. We analyzed and summarized the data to develop a PCMH Function and Form Matrix. The matrix contributes to the development of an explicit theory-based depiction of how an intervention achieves its effects, and can guide decision-support tools in the field. This innovative approach can support transformations of clinical settings and implementation efforts by building on a clear understanding of the intervention's standard core functions and the forms adapted to local contexts' characteristics.
Keywords: complex health interventions; core functions and forms; medical home; patient-centered care; primary care.