Psych · Consultation-liaison — capacity and consent
Capacity and informed consent
Also known as Decision-making capacity · Informed consent · Competence to consent · MacCAT-T · Best interests · Substituted decision-making · Treatment refusal · Mental capacity assessment
Exam-exhaustive fellowship reference on decision-specific capacity and informed consent — four functional abilities (understand/appreciate/reason/communicate and MCA-style understand/retain/use-weigh/communicate), assessment method and teach-back, fluctuating capacity, valid consent elements, best interests and substitute decision principles, mental health law vs capacity law interface, CASC skills. Statutes are jurisdiction-specific; no invented section numbers. FRANZCP-primary, globally tagged.
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Red flags
- Equating disagreement or an unwise refusal with incapacity (outcome bias) — capable adults may refuse recommended treatment
- Global label 'lacks capacity' without naming the specific decision and time of assessment
- Skipping material information disclosure then concluding the person cannot understand
- Treating mental health detention as automatic authority for all medical procedures
- Ignoring fluctuating capacity (delirium, settling mania/psychosis) and failing to reassess or delay non-urgent decisions
- Using family preference as substitute authority without a lawful basis under local legislation
Meet the patient
A 71-year-old man on the surgical ward has a black, wet, foul-smelling forefoot and a rising white cell count. The vascular team want a below-knee amputation today. He says no. He says he has had this foot for seventy-one years and intends to keep it.[4][10]
The registrar's referral reads: Refusing life-saving surgery — please assess capacity. Note what that sentence has already assumed.[2][10]
Two questions are now live and you must answer both. Can he do the four things? And have we actually told him what we are asking him to decide? Most failed capacity assessments fail on the second question, not the first.[2][10]
References16ShowHide
- [1]Appelbaum PS, Grisso T Assessing patients' capacities to consent to treatment N Engl J Med, 1988.PMID 3200278
- [2]Appelbaum PS Clinical practice. Assessment of patients' competence to consent to treatment N Engl J Med, 2007.PMID 17978292
- [3]Grisso T, Appelbaum PS, Hill-Fotouhi C The MacCAT-T: a clinical tool to assess patients' capacities to make treatment decisions Psychiatr Serv, 1997.PMID 9355168
- [4]Raymont V, Bingley W, Buchanan A, et al. Prevalence of mental incapacity in medical inpatients and associated risk factors: cross-sectional study Lancet, 2004.PMID 15488217
- [5]Cairns R, Maddock C, Buchanan A, et al. Prevalence and predictors of mental incapacity in psychiatric in-patients Br J Psychiatry, 2005.PMID 16199799
- [6]Cairns R, Maddock C, Buchanan A, et al. Reliability of mental capacity assessments in psychiatric in-patients Br J Psychiatry, 2005.PMID 16199798
- [7]Okai D, Owen G, McGuire H, et al. Mental capacity in psychiatric patients: Systematic review Br J Psychiatry, 2007.PMID 17906238
- [8]Owen GS, David AS, Richardson G, et al. Mental capacity, diagnosis and insight in psychiatric in-patients: a cross-sectional study Psychol Med, 2009.PMID 18940026
- [9]Hindmarch T, Hotopf M, Owen GS Depression and decision-making capacity for treatment or research: a systematic review BMC Med Ethics, 2013.PMID 24330745
- [10]Sessums LL, Zembrzuska H, Jackson JL Does this patient have medical decision-making capacity? JAMA, 2011.PMID 21791691
- [11]Buchanan A Mental capacity, legal competence and consent to treatment J R Soc Med, 2004.PMID 15340019
- [12]Palmer BW, Harmell AL Assessment of Healthcare Decision-making Capacity Arch Clin Neuropsychol, 2016.PMID 27551024
- [13]Marcó-García S, Ariyo K, Owen GS, et al. Decision making capacity for treatment in psychiatric inpatients: a systematic review and meta-analysis Psychol Med, 2024.PMID 38433596
- [14]Kim SY, Karlawish JH, Caine ED Current state of research on decision-making competence of cognitively impaired elderly persons Am J Geriatr Psychiatry, 2002.PMID 11925276
- [15]Karlawish JH, Casarett DJ, James BD, et al. The ability of persons with Alzheimer disease (AD) to make a decision about taking an AD treatment Neurology, 2005.PMID 15883310
- [16]Palmer BW, Jeste DV Relationship of individual cognitive abilities to specific components of decisional capacity among middle-aged and older patients with schizophrenia Schizophr Bull, 2006.PMID 16192412