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How to assess a patient’s mental capacity

By Dr Clare Sweeney - 02nd Sep 2022

mental capacity

Dr Clare Sweeney, Medico-legal Adviser with the Medical Defence Union, explains that assessing a patient’s capacity is an essential part of getting consent if their mental ability to make a decision is in question.

How to assess a patient’s mental capacity 

Dr Clare Sweeney, Medico-legal Adviser with the Medical Defence Union, explains that assessing a patient’s capacity is an essential part of getting consent if their mental ability to make a decision is in question 

The assessment of a patient’s mental capacity is a routine part of medical practice but can be a source of anxiety. This is especially the case if the assessment is particularly complex, or if the outcome is finely balanced. Fortunately, your medical defence organisation can talk you through the process and below we explain some of the legal and ethical considerations to bear in mind. 

What is capacity and who has it? 

Capacity is the ability to make a decision or take an action that impacts on a person’s life; it indicates that a person is able to make a decision about their own care and treatment. 

A clinician caring for a person who may lack capacity to consent or decline a treatment or proposed course of action needs to assess the patient’s capacity in the first instance. 

As most doctors will be aware, all adults should be considered to have capacity to make decisions about their treatment unless they are shown not to have the capacity to do so. This includes decisions to refuse treatment, even when the involved healthcare professionals believe that (in their eyes) the benefits of the treatment would greatly outweigh the risks. A patient does not need to justify or explain their decision, or even need to have any particular reason for their decision, so long as they have the capacity to make it. 

Capacity depends on the patient and the decision 

Most patients do not simply ‘have’ or ‘lack’ mental capacity – it is time-specific and decision-specific. In addition, a patient’s capacity may fluctuate, either due to their medical condition or for unrelated reasons. A patient who cannot make complex decisions may easily be able to make simpler decisions. Maximising the patient’s ability to exercise their capacity might therefore require a doctor to break down more complex decisions into a series of simpler ones in order to ascertain the patient’s wishes. The fact that a patient currently lacks the capacity to make a particular decision does not mean that they could not make it at some time in the future. Doctors might therefore need to consider, wherever possible, delaying decisions about treatment until the patient has recovered capacity, if this is at all foreseeable. 

Using the four-stage test to assess capacity 

The Assisted Decision-Making (Capacity) Act (ADMA) 2015 is expected to come into force this year. The Act is intended to support and enhance patients’ ability to make decisions, including decisions about their own health and social care. It provides a new legal framework for maximising patients’ ability to have a say in their own healthcare. 

The Act formalises the four-stage test, which will be familiar to most doctors, and which is required to determine whether a patient has capacity to make a specific decision. It says that a patient will lack the capacity to make the decision if they are unable to: 

  • Understand all of the information relevant to the decision; 
  • Retain the information for long enough to help them make the decision; 
  • Use or weigh up that information when making their decision; 
  • Communicate their decision (by any means, such as by assistive technology). 

In cases where a patient lacks capacity to make a particular decision, doctors will still be required to treat the patient in accordance with their ‘will and preferences’ where these can be reasonably ascertained. Doctors should therefore explore these during their discussions with the patient and their family and carers about the proposed treatment. 

Decision Support Service 

The Act has led directly to the establishment of the Decision Support Service (DSS), which will support patients who might otherwise have difficulty exercising their capacity and making decisions. The service should become fully operational later this year. Among the aims of the DSS is the raising of public awareness of issues related to mental capacity. 

Where patients do not have the capacity to do so, the Medical Council says that doctors should still listen to their views and involve them, as far as they are able, in all decisions about their healthcare 

The DSS will maintain a searchable register of patients who have decision support arrangements in place, and who is involved in these. This means that doctors should be able to establish more easily whether they should be speaking with a specific person when making decisions about a patient’s treatment. 

In some cases, these will be court-appointed representatives; in others the person named in the arrangement will be a person selected by the patient themselves because they know and trust them. There will be five different levels of support arrangements depending on how much assistance that particular patient needs with decision-making. 

The DSS will also maintain a register of, and monitor the actions of ‘designated healthcare representatives’, who can be named by patients making advance healthcare directives, in which they set out their wishes for future treatment. 

Your ethical duties 

The Medical Council has issued detailed guidance about mental capacity to the profession in its Guide to Professional Conduct and Ethics. For many years the guidance required doctors to help patients to make decisions about their own treatment. Where patients do not have the capacity to do so, the Medical Council says that doctors should still listen to their views and involve them, as far as they are able, in all decisions about their healthcare. 

The guidance goes on to say that if a patient lacks capacity the doctor must establish whether there is anyone with the legal authority to be able to make decisions on the patient’s behalf. If nobody has this authority then the doctor must make decisions in the patient’s best interests, taking account of their previously and currently expressed wishes, and the views of those close to the patient. The guidance says that doctors must also discuss their decisions with other involved healthcare professionals. 

In conclusion 

Doctors’ approach to the issue of mental capacity and its impact on patient consent has undergone a sea change within the last generation. Gone are the days of medical paternalism, when ‘doctor knows best’. It has taken many years for these gradual changes to become embedded in doctors’ routine practice, and for decision-making to become more patient-centred. 

The imminent commencement of the new Act will require further change in doctors’ approach to assessing capacity. Your medical defence organisation can help to guide you on this complex area. 

Medical Defence Union membership is open to consultants and hospital doctors not currently in training posts working in public hospitals. To find out more see or follow us on Twitter @the_mdu. 

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