Dental teams are already seeing the impact on oral health and treatment planning decisions as older people are more likely to have medical co-morbidities and impairments. The causes of cognitive impairment can be multifactorial; medication side effects, metabolic and/or endocrine imbalances, delirium due to infections, depression and dementia. Currently, 850,000 people in UK are living with dementia which is projected to increase to over one million people by 2025 (Prince et al., 2014).

The process of obtaining consent

Dental professionals have a legal and ethical obligation to inform patients of the options, risks and benefits of the proposed dental treatment. Consent is given voluntarily, based on appropriate information that has been understood by a person who has capacity to make the decision in question.

Failure to gain consent could lead to a claim for compensation or even an accusation of battery or assault. If an adult has the capacity to make a voluntary and informed decision to consent to or refuse a particular treatment, their decision must be respected even if it is deemed unwise.

What is capacity?

Capacity is the ability of a person to make a specific decision at the time it needs to be made. Capacity and incapacity are not concepts with clear boundaries. They appear on a continuum which ranges from full capacity to full incapacity with degrees of capacity in between.

One of the really difficult and complex challenges is to decide the extent to which a person's capacity must be impaired before they lose their right to make a decision. The Mental Capacity Act (MCA) 2005 is a legal framework in England and Wales for decision making on behalf of adults who lack capacity to make decisions for themselves on healthcare, personal welfare and financial matters. Scotland is governed under the Adults with Incapacity Act 2000 and Northern Ireland is governed under the Mental Capacity Bill 2015.

The MCA asks if the individual has the capacity to make a decision at a specific time, not if they have the ability to make decisions generally. Capacity must be re-assessed at each visit, with recognition that people with an impairment or disturbance in the way their mind or brain works may be capable of making a particular decision at the time it needs to be made. Assumptions regarding capacity should be avoided based on the patient's age, diagnosis, behaviour or appearance.

Who can assess capacity?

The assessment of capacity may be carried out by anyone who requires a patient's consent should they be concerned about the patient's capacity. Within dentistry, the assessor will be the person who is deciding on treatment options for the individual at the time the decision needs to be made.

The assessor must understand MCA and its practical implementation. If there are doubts about capacity and the decision is a serious one, expert advice from a psychiatrist or psychologist with particular experience in assessing capacity can be sought. Overall, treatment decisions still rest with the health professional delivering care.

How to assess capacity

When proposing dental treatment, it is the clinician's responsibility to ensure the correct process is followed when assessing capacity by using a MCA assessment checklist.

The MCA details a two-stage test of capacity, and is underpinned by five main principles.

Two-stage test, part 1: the diagnostic test

Is there an impairment or a disturbance in the functioning in the mind or brain that is affecting the person's ability to make a decision?

For example: mental illness, dementia, learning disability, physical or medical conditions that cause confusion, drowsiness or loss of consciousness, delirium, concussion following a head injury etc.

Two-stage test, part 2: the functional test

A person is unable to make their own decision if they cannot do one or more of the following:

• understand the information
• retain that information
• use and weigh up the information as part of the decision making process
• communicate their decision.

The five principles of the MCA

• Capacity is assumed.
• People should be helped to be able to decide.
• People are allowed to make unwise choices.
• Treat people in their best interest.
• Use the least restrictive option.

Points to consider within dentistry

• There must be a comprehensive medical history. Information sharing is part of the provision of safe and effective care and it may be prudent to consider contacting the patient's general medical practitioner (GMP) to arrange further investigation of symptoms or enquire about diagnoses and co-morbidities.
• Have you presumed capacity, or do you have a clear reason to question it? Remember a diagnosis (ie, dementia) alone is not sufficient reason to assume a person does not have capacity for a decision.
• Have you been able to support the patient in making their decision? Can the decision wait? Is there a time of day that is better for the patient? Is it possible to see the patient at home in a familiar environment?
• Would it help to have another person present who knows the patient well to support decision making?
• Is the cognitive impairment temporary or permanent? It is important to consider that an older person can become confused from infections so might not be able to make informed decisions at that time. Does the decision need to be made now or can it be revisited at a later date?
• Does the patient require help to understand the information you are giving them - for example, supporting written information, pictures, more simple language or a hearing loop?
• Is there any reason to suggest the patient does not understand the information, is not able to answer questions appropriately or to ask relevant questions?
• Is the patient able to retain the information long enough to weigh up the options, risks and benefits to make a decision? Notebooks, for example, could be used to record information which may help a person to retain it.
• A second opinion may be beneficial from another colleague if there is doubt in assessing capacity.
• If your assessment concludes that the patient does not have capacity, is the dental treatment proposed in their best interest - who else should be involved in the decision?
• Emergency treatment can be provided that is immediately necessary to stabilise/prevent deterioration in the patient without consulting others (MCA, 2005).

There are some safeguards to be aware if a patient lacks capacity.

• Lasting power of attorney for health and welfare decisions. This appointed person should be part of the decision process on the patient's behalf.
• A valid advanced decision to refuse treatment, then this must be followed.
• Informal statements about future wishes are not legally binding, but considered in an assessment of best interest.
• A decision made on behalf of a patient who lacks capacity must be done in their best interests…
• …and in the least restrictive way.
• A best interest discussion/meeting may be required where there is conflict in decision making, assessment of capacity or when complex treatment is required; for example, multiple extractions, or treatment under conscious sedation or general anaesthetic (Kaul et al. 2010b).
• Those who lack capacity and have no relatives, friends or unpaid carers to act as advocates should have a best interest discussion. Independent mental capacity advocates are only involved with serious medical treatment.
• A record that mental capacity assessment has taken place should be in the patient's notes. What is reasonable to expect by way of documentation of the process will depend upon the reason why the assessment is being conducted. A restoration of a tooth with local anaesthesia will not demand the same level of detail as one for an examination under general anaesthetic. The more complicated or serious the decision, the greater the evidence of capacity required and the more detailed the assessment of capacity.

Other considerations

Advance care planning describes the exchange between a patient, friends, relatives and carers about their future wishes and priorities for care. If you find that a patient is in the early stages of a progressive cognitive illness then it may be appropriate to have a sensitive discussion with the patient about their wishes, needs and preferences for future dental care and record it whilst the patient has capacity.

There is a risk that patients who lack capacity merely comply with dental professionals when asked to consent to an intervention, and are recorded as having consented without a mental capacity assessment having been carried out. In other cases, patients' next of kin may be given a consent form to sign even though they may have no power to authorise treatment or care on the patient's behalf.