Table 1.

Detailed programme theories

Programme theory (PT) label	Programme theory detail	Subgroups most relevant to
PT1. Uncertainty about symptoms causing anxiety	When there is uncertainty surrounding symptoms (M) either because they do not fit with people's expectations or prior experience (eg last longer, are more severe, unfamiliar or do not respond to self‐care in the expected timescale) (C/M), this increases the perceived risk that the problem may be serious (M) and an immediate need to establish what is wrong and obtain reassurance (M). This concern prompts the use of the ED (O), where it is perceived the most appropriate resources and expertise required to establish cause can be accessed quickly (C), often in the context of timely or satisfactory answers not having been received from primary care services (C).
PT2. Heightened awareness of risk as a result of experience or knowledge of traumatic health events leading to anxiety	When people have experience of previous traumatic health incidents (eg delayed help‐seeking leading to serious consequences), or awareness of such incidents experienced by others or in the media (C), they have increased anxiety and awareness of danger (C/M) and reduced confidence in their own judgement (M). They are therefore unwilling to take risks when a health problem arises (M), leading them to seek immediate help and advice from an expert in the form of emergency care including ambulance services and EDs (O).
PT3. Fear of consequences when responsible for others	When people are in a position of responsibility for others they are less willing to take risks with someone else's health than with their own and fear the consequences (eg distress/guilt, dismissal, litigation) (M) of not doing ‘the right thing’. This leads them to seek or to recommend seeking urgent care, particularly the ED (O).	Parents of a child, carers of vulnerable elderly people, people with chronic conditions, health services or other service professionals, for example teachers
PT4. Inability to get on with daily life	When people are prevented them from undertaking their normal lives, roles or responsibilities (eg paid work, childcare) (C) this creates a need to get back to normal quickly (M), to get on with their lives and discharge their responsibilities. This prompts use of urgent care (O) because it can resolve a problem quickly by being both more accessible and efficient than alternatives (C).	parents of young children, people working in jobs where they cannot afford to take time off or it is difficult to take time off
PT5. Need for immediate pain relief	When people are in pain or discomfort which they find intolerable (C/M), and they believe or experience that no primary care appointments are available within an acceptable time period (C), they seek care from a more urgent service—usually the ED (O)—because of a need to obtain prompt relief from their distress (M).
PT6. Waited long enough for things to improve	When people delay seeking primary care treatment (for various reasons including deliberation and indecision, cost of treatment, lack of transport, complex living situations, mistrust of health services and work responsibilities) (C) they wait, often using self‐help measures, and hope the situation will improve or go away (C). The condition reaches a ‘tipping point’ where either it is no longer tolerable (M) or other circumstances force a decision (M), and people feel they cannot wait any longer (M). At this point, if a primary care service is unavailable to them (C), they feel they have no choice but to use an emergency service (O).
PT7. Stressful lives/ can't cope	When people are already experiencing significant stresses which impact on the internal and external resources available to them (money, time) (C) they have less capacity to cope with the additional challenge of a new or changed health problem. Symptoms are therefore likely to trigger emotional distress, including feelings of loss of control and helplessness (M), leading them to use emergency services because this is less burdensome than making an appointment with a GP. This is more likely to occur when people cannot easily or quickly access a primary care service (C).	low socio‐economic status, parents of a child, isolation, demanding work, mental health problems
PT8. Following advice of trusted others	When people are anxious or concerned about a health problem and have sought the advice of trusted others (C)—either in their social network (eg family) or health professionals (particularly primary care staff)—and have been advised to seek urgent care, particularly the ED (M), they are likely to then use those emergency services (O).
PT9. Perceptions or prior experiences of services	When people have individual experience or knowledge, or cultural beliefs, about the differing quality or availability of primary and emergency services (eg primary care offering inadequate diagnosis and care or discrimination (US context only), or EDs having better resources, expertise or more thorough care (C), they are likely to choose emergency care, particularly the ED (O) in which they have more trust and confidence (M).	people previously referred to emergency services by primary care staff, parents with young children, chronic conditions
PT10. Poor access to a GP	When people are unable to obtain an appointment with a primary care practitioner (C/M) this can further exacerbate the feelings of anxiety and cause panic (M). Individuals can experience feelings of frustration (M), mistrust (M), and the perception of an uncaring service (M), feeling they have no other choice (M) but to contact an emergency service (O).