Table 3.

Descriptions of key mechanisms in the Revised Program Theory

Mechanism Category	Detailed CMOs
Anxiety	Facilitation of SDM: 1. If a patient faces a moderately difficult decision regarding their treatment, then they may experience a moderate increase in their anxiety fostering a drive to engage within SDM.Moderate difficulty of decision (C) + Moderate anxiety (M) ➔ Patient engages in SDM (O) 2. If a HCP has received system support to gain skills in SDM, then they may have reduced anxiety about using it within their consultation, increasing their engagement in SDMSystem support for SDM (C) + Reduced anxiety (M) ➔ HCP engagement in SDM (O) Hindering of SDM: 1. If a physician perceives high patient anxiety, then they may unilaterally decide it is inappropriate to engage in SDMPatient displaying high anxiety characteristics (C) + HCP perception of patient anxiety (M) ➔Low engagement in SDM by the HCP (O) 2. If a patient has a difficult decision regarding their treatment, then they may experience a debilitating increase in anxiety resulting in low patient engagement in SDMHigh difficulty of decision (C) + High patient anxiety (M) ➔ Low patient engagement in SDM (O)
Perception of capacity to access external support	Facilitation of SDM: 1. If a HCP perceives that the system offers supports to aid in the decisional process, then they are more like to engage in SDM.Perception of System support (C) + Perception of capacity to access external support (M) ➔ high engagement in SDM (O) 2. If a patient believes that they have supports beyond the HCP, then they are likely to experience reduced anxiety and increased self-efficacy, resulting in high SDM engagementPerception of capacity to access external support (C) + Reduced anxiety (M) + Increased self-efficacy (M) ➔ High SDM engagement (O) Hindering of SDM: 1. If the HCP is dealing with a complex diagnosis and does not perceive that they are able to access external support such as journal articles, then they are likely to experience low self-efficacy in SDM and have reduced SDM engagement Complex diagnosis (C) + Perception of capacity to access external support (M) + Low self-efficacy ➔ Low SDM engagement (O)
Perception of other party’s capacity	Facilitation of SDM: 1. If HCPs have received the appropriate training through their system, then they are able to adjust their SDM approach based on their perception of patient capacity, increasing HCP engagement and improving the patient’s ability to engage in SDM. System support (C) + Accurate perception of patient capacity (M) ➔ High patient and HCP engagement in SDM (O) Hindering of SDM: 1. If a patient is displaying high levels of anxiety, then the HCP may perceive that they do not have the capacity to participate in decision-making, resulting in a low HCP engagement in SDMHCP perception of patient anxiety (C) + HCP perception of patient capacity (M) ➔ Low HCP engagement in HCP (O)
Perception of time	Facilitation of SDM: 1. If the HCP perceives they have system support to give patients as much time as they require for decision-making, then the HCP and patient will have a higher level of engagement in SDMSystem support (C) + Perception of time (M) ➔ High engagement for HCP and patient in SDM process (O) Hindering of SDM: 1. If a system is set for a fee-for-service schedule – which does not incorporate consultation time appropriately into the schedule – and the HCP perceives that SDM increases appointment times, the HCP may elect to reduce their time spent with the patient, negatively impacting the HCPs level of engagement. Negative system support for SDM (C) + Perception of inadequate time to conduct SDM (M) ➔ Low HCP engagement in SDM (O) 2. If a HCP perceives that a decision must be made immediately, they may not engage the patient as they do not perceive the time to incorporate their opinions. As an example, if an individual comes in with a life-threatening emergency, the HCP is more likely to act without patient consultation.High complexity of diagnosis (C) + Perception of limited time to make a decision (M) ➔ Low engagement of SDM by the HCP, limiting patient engagement (O) 3. If a HCP believes that they do not have the flexibility within their schedule (e.g., case load, system support to appropriately consult, etc.), they may elect to not involve, or inadequately involve, the patient in the decision process. Low system support (C) + Perception of inadequate time available (M) ➔ Low SDM engagement (O)
Self-efficacy	Facilitation of SDM: 1. When the patient is able to express their preferences and values through the implementation of SDM, then they experience higher confidence in their ability to participate in SDM, resulting in higher levels of SDM engagement. System support for SDM use (C) + Increased patient self-efficacy (M) ➔ High engagement in SDM (O) Hindering of SDM: 1. If an individual (HCP or patient) does not believe they are capable of participating in SDM, then they will avoid attempting engagement.Unidentified context + Low self-efficacy (M) ➔ Low engagement in SDM (O)
Trust	Facilitation of SDM: 1. If a patient trusts the HCP (or a HCP trusts the patient), then they will engage in SDM. Pre-existing relationship (C) + trust (M) ➔ high engagement in SDM (O) 2. If the HCP perceives that the patient trusts them, then the HCP will engage in SDM. Unidentified context + perceived trust (M) ➔ high engagement in SDM (O) Hindering of SDM: 1. If a patient does not trust the HCP (or a HCP does not trusts the patient), then they will not engage in SDM. Pre-existing relationship (C) + Lack of trust (M) ➔ Low engagement in SDM (O)
World view	Facilitation of SDM: 1. If a HCP is willing to incorporate the patient’s world view of the biomedical model into the treatment options, then the patient more likely to engage in SDM. For example, patients may not wish to explore certain treatment options (such as blood transfusions) based on their world view. HCP acceptance of world viewa (C) + World view (M) ➔ High SDM engagement (O) Hindering of SDM: 1. If a HCP is not willing to incorporate the patient’s world view of the biomedical model into the treatment options, then the patient unlikely to engage in SDM.HCP un-accepting of world viewa (C) + World view (M) ➔ Low SDM engagement (O)
Recognition of decision	Facilitation of SDM: 1. If a diagnosis is complex and requires a lot of information exchange, then HCPs are more likely to recognize that the patient must be involved in the decision and SDM engagement increases.Complex diagnosis (C) + Recognition of decision (M) ➔ SDM engagement (O) Hindering of SDM: 1. If a HCP recognizes that a decision is required to be made, then SDM engagement will occur.Unidentified context (C) + Recognition of decision requirement (M) ➔ SDM engagement (O)

This table presents the CMOs for each mechanism set identified within the program theory. ^aitalics represent hypothesized contexts