This research aims to establish the number of patients coming to Emergency Departments (EDs) with issues relating to mental health, alcohol or drugs, or in some form of psychological distress, including those for whom this was not the main reason for attending ED. We will collect anonymous information on age, gender, ethnicity, when and how they came to the ED, where and how they are cared for whilst in the ED, and what happens to them afterwards. With this information we hope to build a better picture of these patients so we can go on to design and test ways to improve their care in the future.

Those presenting to the Emergency Department with mental ill health, substance misuse or in crisis have a worse patient journey than those presenting with physical issues alone. They wait twice as long to be seen1 and have poorer experiences. Recognising this, the RCEM/James Lind Alliance Priority Setting Partnership has placed mental health at the top of the Emergency Medicine research agenda. The question asked is: "How can care for mental health patients be optimised, whether presenting with either/both physical and mental health needs; including appropriate space to see patients, staff training, early recognition of symptoms, prioritisation, and patient experience?" An explicit research agenda has yet to emerge from this very broad question. At the most basic level, the patient population needs to be defined, the scale of the problem quantified, and current practice patterns and variation described in detail.

It has been estimated that the proportion of ED attendances related to "mental health disorders" is 4%. However these estimates are derived from retrospective data and are dependent on accurate diagnosis coding. There is a lack of data on dual diagnoses, which Scotland's Mental Health strategy has outlined as a key area for action, recommending opportunities to "pilot improved arrangements for dual diagnosis for people with problem substance use and mental health diagnosis". A literature review aiming to build a 'Typology' of psychiatric emergency services in the UK emphasised wide variation in provision and heterogeneity of models. No prospective study has yet quantified this variation in terms of waiting times, types of assessment offered, disposition and outcomes. The success of other large observational studies on ED presentations such as syncope, acute aortic syndromes and frailty suggests that a similar methodology could be applied to mental health and related presentations.

Inclusion Criteria:

• Issues of mental health AND/OR
• Issues of substance use AND/OR
• Psychological distress (this refers to patients without an established mental health or substance use disorder who nonetheless present in a distressed state, where distress is not caused by a readily identifiable and treatable physical condition) AND/OR
• Where the treating ED team feel the patient would benefit from some form of mental health or addictions assessment or intervention, whether carried out by ED staff, specialist services or third sector agencies.

Exclusion Criteria:

1. Patients aged 10 and under.
2. Patients with distress caused by a physical condition, relieved by appropriate treatment.
3. Delirium, unless caused by a mental health- or substance-related disorder.
4. Patients with alcohol intoxication alone, without other evidence of harmful use of alcohol and without evidence of psychological distress.

Patients presenting to the Emergency Department (ED) with issues of mental health, substance use or psychological distress, whether or not this was the primary reason for presentation.