Psychiatric interview: objectives, structure, content, and process. Standardized assessment instruments in psychiatry

01Objectives

The psychiatric interview is where most psychiatric diagnoses are made: physical examination and tests play a smaller part than in other specialties, and the diagnosis rests on what the patient says, what the doctor observes, and the later course. It has several aims at once:

• To make a diagnosis, or a differential diagnosis, with the evidence for and against each possibility.
• To assess risk to the patient, to others and from others.
• To understand the person, their history, circumstances, strengths and own explanation, for the formulation.
• To begin the therapeutic alliance: a patient who feels heard is more likely to return, to tell the truth and to accept treatment.
• To agree a plan, explain it, and give information and hope.

02Structure

An assessment of an adult usually takes 45 to 90 minutes, and an emergency assessment is shorter and focused on the acute problem and risk, with the rest filled in later.

1. 1

   Prepare

   Read the referral and the notes, especially past violence and risk. Tell a colleague where and whom you are seeing, and know the alarm. Arrange an interpreter if needed.
2. 2

   Open

   Introduce yourself and your role, explain the purpose, the length and what you already know, and the limits of confidentiality. Ask whether the patient wants any companion present.
3. 3

   Patient-led history

   Open questions about what has been happening. Listen, let the patient talk, and note the mental state as you go.
4. 4

   Doctor-led history

   Clarify the symptoms (are these true hallucinations? does the mood vary through the day?) and screen the areas not yet mentioned: mood, anxiety, psychotic symptoms, substances, cognition, risk.
5. 5

   Background

   Complete the past, family, personal, forensic and social history and the premorbid personality.
6. 6

   Examine

   Complete the mental state examination, a cognitive test where indicated, and the physical examination.
7. 7

   Close

   Summarise back to the patient, ask what has been missed, give your understanding of the problem, agree the next steps and the next contact. Leave about a quarter of the time for this.

The assessment goes on afterwards, with a collateral history from relatives, the general practitioner and old records (with consent, unless risk overrides it), nurses' observations and review as the illness evolves: every psychiatric diagnosis is to some degree provisional.

03Content

The psychiatric history

A collateral history matters most where insight or memory is impaired, in psychosis, mania, delirium, dementia and intoxication, and where the patient's account and the referral differ.

The mental state examination

The mental state examination is the psychiatric equivalent of the physical examination: an ordered description of the patient's experience and behaviour at the time of the interview, recorded with examples in the patient's own words. Much of it is observed during the history.

The psychopathology behind each heading is described in the psychopathology topics, from consciousness and psychomotor activity to thought and perception and memory. Disagreeing with the doctor is not in itself lack of insight: a patient can understand an illness fully and still decline a treatment.

Risk, in brief

Risk is assessed in every patient and recorded as a heading of its own: risk to self (suicide, self-harm, self-neglect), to others (violence, and the safety of children and other dependants) and from others (exploitation, abuse), with risks such as driving where they apply. Thoughts of suicide are asked about in steps, from hopelessness and thoughts that life is not worth living to thoughts of ending it, plans, preparations and past attempts, together with what keeps the person going.

Risk scales predict poorly. UK guidance on self-harm advises not using risk assessment tools or scales, or a rating of low, medium or high risk, to predict suicide or to decide who is treated or discharged; the assessment instead looks at each person's needs and risks and leads to a safety plan. The full assessment and management are in suicidal and aggressive behaviour.

Cognitive testing

A cognitive examination is needed whenever an organic disorder is possible: in older patients, with confusion, memory complaints, a first psychosis or a change in personality. It covers the level of consciousness, orientation, attention (months of the year backwards, serial sevens, digit span), memory (registering and recalling a name and address, recent and remote events), language (naming, repetition, comprehension, writing), visuospatial function (copying a figure, drawing a clock) and executive function (verbal fluency, abstraction, alternating hand sequences). A standard instrument gives it a score (see below). Poor attention points to delirium, a gradual decline in memory with a clear consciousness to the dementias.

Physical examination and investigations

The physical examination is part of every full psychiatric assessment, because physical illness can cause or worsen mental symptoms, mental illness and its drugs cause physical harm, and a baseline is needed before treatment. It records weight, body mass index, pulse and blood pressure, and looks especially at the neurological examination (extrapyramidal signs, tremor, gait, focal signs), signs of self-harm, injecting, liver disease, thyroid disease and malnutrition.

Formulation

The case is summarised in a formulation: a short synopsis, the differential diagnosis with the working diagnosis, the causes in this patient, a management plan and the likely prognosis. The causes are set out in the biopsychosocial model, crossed with the four Ps.

The example is of a young man with a first psychosis. The plan follows the same grid: immediate, short-term and long-term measures, each biological, psychological and social, with the perpetuating factors as the main targets.

04Process

Setting and safety

• A quiet, private room, chairs of the same height at an angle rather than across a desk, an easy way out for both doctor and patient, the alarm at hand and nothing that could be used as a weapon.
• Violence is rare, and most risk is to the patients themselves, but it is thought about before every new interview; its best predictor is past violence.
• Interpreters: a professional interpreter, ideally sharing the patient's culture, even when the patient speaks some of the language. Relatives interpret only in an emergency, and children are never used as interpreters.
• Notes are made during or soon after the interview, dated and signed, with key symptoms in the patient's own words.

Interviewing skills

A delusion is neither argued with nor agreed with: the doctor acknowledges how real and distressing it is for the patient and explores it. Some patients need their own approach: the agitated (safety, a calm voice, a shorter interview), the mute (observe, offer writing, think of catatonia and physical causes), the intoxicated (reassess when sober unless there is an emergency), the manic and over-talkative (polite, firm interruption and closed questions) and the cognitively impaired (simple questions, hearing aids and glasses, an informant).

05Standardised assessment instruments

Instruments make assessment more reliable, help screening, measure severity and show change with treatment. They come in three kinds: structured diagnostic interviews, clinician-rated scales and self-report questionnaires. A fully structured interview asks fixed questions in a fixed order and can be used by trained lay interviewers; a semi-structured one leaves the clinician to probe and judge.

Diagnostic interviews

Rating scales