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Instruments for assessing medical decision-making capacity

Clinical Question:
Are there useful instruments for assessing medical decision-making capacity?

Bottom Line:
Cognitive assessment has been shown to be strongly related to medical decision-making capacity. The Mini-Mental State Exam (MMSE) is useful when the score is less than 20 or greater than 24. Other useful instruments include the Aid to Capacity Evaluation (ACE), the Hopkins Competency Assessment Test (HCAT), and the Understanding Treatment Disclosure (UTD). (LOE = 1a-)

Reference:
Sessums LL, Zembrzuska AH, Jackson JL. Does this patient have medical decision-making capacity? JAMA 2011;306(4):420-427.  [PMID:21791691]

Study Design:
Systematic review

Funding:
Unknown/not stated

Setting:
Various (meta-analysis)

Synopsis:
These investigators searched MEDLINE and EMBASE for English-language-only studies that evaluated the accuracy of available instruments to assess the medical decision-making capacity in the office setting. Only high-quality prospective studies (n = 43) with a level of evidence rating of at least 3 on a 5-point scale met eligibility requirements. The majority of studies assessed cognition, which has been shown to be strongly related to decision-making capacity. The gold standard was either a forensic psychiatrist or an expert competency panel. The majority of studies (n = 23) used the MMSE. MMSE scores of less than 20 significantly increased the likelihood of incapacity (positive likelihood ratio [LR+] = 12; 95% CI, 5.3-27). Scores greater than 24 significantly lowered the likelihood of incapacity (negative likelihood ratio [LR-] = 0.14; 0.06-0.34). MMSE scores of 20 to 24 were not effective in assessing decision-making capacity. Three other useful instruments included the ACE (LR+ = 8.5; 3.9-19; LR- = 0.21; 0.11-0.41), the HCAT (LR+ = 54; 3.5-846; LR- = 0.0; 0.0-0.52), and the UTD (LR+ = 6.0; 2.1-17; LR- = 0.16; 0.06-0.41). Although the numbers for the HCAT look great, the authors point out that there was only one small study of the HCAT, with a small sample size. The ACE uses scenarios specific to the patient?s condition. The authors provide a reference for free copies of each instrument. Physician judgment alone often failed to recognize incapacity (LR- = 0.61; 0.48-0.74), but when a physician suspected incapacity, he or she was usually correct (LR+ = 7.9, 2.7-13).

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