Box 3.

Facilitators and barriers of access to primary healthcare services mapped against the Theoretical Domains Framework

TDF domain	TDF descriptor	Subtheme	Facilitator	Barrier
Beliefs about capabilities	Acceptance of the truth, reality, or validity about an ability, talent, or facility that a person can put to constructive use	Patients’ perceived ability (or lack of) to find a healthcare provider	✓	✓
		Patients’ perceived ability (or lack of) to integrate with the norms and rules within mainstream services	✓	✓
Beliefs about consequences	Acceptance of the truth, reality, or validity about outcomes of a behaviour in a given situation	Patients’ beliefs about the consequences of not receiving health care	✓	✓
		Consequences of continuity of care (or lack of)	✓	✓
		Consequences of being discharged onto the streets with no primary care providers		✓
		Consequences of fragmented services on health		✓
Emotions	A complex reaction pattern, involving experiential, behavioural, and physiological elements by which the individual attempts to deal with a personally significant matter or event	Feelings of embarrassment when seeking health care		✓
Environmental context and resources	Any circumstance of a person’s situation or environment that discourages or encourages the development of skills and abilities, independence, social competence, and adaptive behaviour	Lack of patient ‘fixed abode’ and photographic ID		✓
		Signposting (or lack of) to appropriate services	✓	✓
		Patients’ lack of resources to pay for public transport or make calls for appointments		✓
		Patients’ lack of resources to search services in their local areas		✓
		Availability (or lack of) facilities to promote medication adherence	✓	✓
		Discharged from hospitals onto the streets		✓
		Unfavourable eligibility criteria for access to substance misuse and mental health services	✓
		Facilitated registration for primary care services through temporary shelters	✓
Goals and intentions	Mental representations of outcomes or end states that an individual wants to achieve	Patients’ intentions to seek health care	✓	✓
Knowledge	An awareness of the existence of something	Patients’ knowledge/lack of knowledge of mainstream services available in their area	✓	✓
		Patients’ knowledge/lack of knowledge of SPHCPH for people who are homeless available in their areas	✓	✓
		Patients’ lack of knowledge of the rules and policies of mainstream practices	✓	✓
		Lack of knowledge among mainstream frontline staff about eligibility for registration of patients who are homeless		✓
		GPs’ knowledge/lack of knowledge of the complexity of patients’ health conditions	✓	✓
Memory, attention, and decision processes	The ability to retain information, focus selectively on aspects of the environment, and choose between ≥2 alternatives	Committing crime to go to prison to access health care		✓
Reinforcement	Increasing the probability of a response by arranging a dependent relationship, or contingency, between the response and a given stimulus	Proactive follow-up of patients at the SPHCHP	✓
Skills	An ability or proficiency acquired through practice	Patients’ lack of skills in completing paperwork and navigating through the system		✓
Social influences	Those interpersonal processes that can cause individuals to change their thoughts, feelings, or behaviours	Support from friends and families in registration process	✓
		Social network to facilitate appointments and engagement	✓
		Perceived stigma and discrimination from other patients		✓
		Perceived stigma and discrimination from healthcare staff		✓
Social/professional role and identity	A coherent set of behaviours and displayed personal qualities of an individual in a social or work setting	Trust (or lack of) between healthcare staff and patients	✓	✓
		Self-identity as a person who is homeless		✓
		Poor handover of patient information across healthcare professionals and settings		✓

✓ TDF = Theoretical Domains Framework; TDF domains for optimism and behavioural regulations were not identified in the data. The domains for goals and intentions are presented together in the data, meaning that 12 TDF domains are presented in 11 rows. SPHCPH = Specialist Primary Healthcare Centre for People who are Homeless.