Assessment of competence to complete advance directives: validation of a patient centred approach.(Statistical Data Included)

Abstract

Objective To develop a patient centred approach for the assessment of competence to complete advance directives ("living wills") of elderly people with cognitive impairment.

Design Semistructured interviews.

Setting Oxfordshire.

Subjects 50 elderly volunteers living in the community, and 50 patients with dementia on first referral from primary care.

Main outcome measures Psychometric properties of competence assessment.

Results This patient centred approach for assessing competence to complete advance directives can discriminate between elderly persons living in the community and elderly patients with dementia. The procedure has good interrater (r=0.95) and test-retest (r=0.97) reliability. Validity was examined by relating this approach with a global assessment of competence to complete an advance directive made by two of us (both specialising in old age psychiatry). The data were also used to determine the best threshold score for discriminating between those competent and those incompetent to complete an advance directive.

Conclusion A patient centred approach to assess competence to complete advance directives can be reliably and validly used in routine clinical practice.

Introduction

Advance directives ("living wills") for medical care have been widely advocated as a means of extending the autonomy of patients to situations when they are incompetent. However, their impact has been surprisingly small. Despite legislation in the United States aimed at encouraging the completion of advance directives, less than 10% of healthy Americans have completed one.[1] The question remains as to how advance directives can be developed and effectively implemented in clinical practice. A pressing ethical problem in their use is that competent people may not always be well placed to make decisions concerning their future incompetent selves.[2] It is difficult for healthy people to imagine the whole range of situations that might befall them. It seems more worthwhile for advance directives to be completed at a time when people already have some disease or disability, enabling doctors to give realistic guidance about possible future situations.

A number of commentators, including the British Medical Association, have argued that dementia is one clinical situation for which an advance directive could potentially be useful.[3 4] An important question, therefore, is whether individuals with dementia are competent to complete an advance directive.

Silberfeld has suggested criteria to test the capacity to complete an advance directive.[5] These criteria examine general competence to complete a directive in a way analogous to the assessment of testamentary capacity.[6] They focus on whether the individual understands the nature and purpose of an advance directive; but they do not assess whether an individual is capable of understanding actual possible future clinical situations. Such understanding is critical to competently completing an advance directive. The Hopkins competency assessment test, which has also been used to test the competence of elderly patients to write advance directives, has similar limitations.[7]

There is, therefore, a need for a method to assess the competence of patients with dementia to complete an advance directive. Our aim was to develop a patient centred approach to enable those with cognitive impairment to complete an advance directive, and to assess the validity of the procedure. In doing this we have taken account of the importance of properly understanding the future imagined clinical situation. We report the development and psychometric properties of such a procedure.

Subjects and methods

Instrument design

Competence is specific, not global--that is, an …