It is time to recognise shared decision-making as a complex intervention

Shared decision-making (SDM) is a core component of personalised health care. Populations continue to diversify in their health and social care needs. We argue that established SDM models (focusing on the interaction between patient and practitioner) do not reflect the complexity of patient presentations nor the wider influences on patients' health and health care encounters. The route from SDM to positive health and health service outcomes are currently obscured. For SDM to be utilised without limit, and for SDM to impact health care policy, it is best understood as a complex intervention.

SDM as a complex intervention is characterised by multiple interacting components, influenced by agents acting at several levels of a socioecological model (personal-, interpersonal-, organisational-, societal-, policy- level). The components have non-linear pathways (from cause to effect) existing within and interacting with the context in which SDM is implemented. SDM components are tailorable: Tailoring can enable personalised care for individuals and effect changes in desired outcomes for specific populations and settings. The development of programme theory, for example utilising logic modelling, will be essential for articulating and planning the evaluation of these complex pathways. A standardised framework of SDM outcomes, spanning the socioecological model, would guide the assessment of SDM process and effect. Programme theory, logic modelling, and consistent assessment will together reveal the route to positive outcomes for patients, carers, practitioners and health services and, in turn, will impact policy.

It is time to recognise SDM as a complex intervention. Simplistic definitions should no longer be attempted. SDM should be conceptualised as being wider than the consultation itself with components that are defined by and tailored to the context of its adoption, implementation and sustainability, considering influences that span the socioecological model of the health care system.