Assessment of Patients' Competence to Consent to Treatment

clinical pr acticehavioral Research, 2 and in the judgment of manyexperts, it reflects how courts actually deal withthese cases.Approaches to AssessmentGiven the requirement of competence for validinformed consent, the assessment of the patient’scapacity to make decisions is an intrinsic aspectof every physician–patient interaction. Usually, theassessment will be implicit, since in the absenceof a reason to question a patient’s decision making,the presumption of competence will prevail. Whenan explicit competence evaluation is required, physiciansshould be aware of the relevant criteria andshould be encouraged to use a structured approachto assessment. In one set of studies, simply providingphysicians with specific legal standards toguide their judgments, similar to the criteria inTable 1, significantly increased interrater agreement(the kappa statistic for agreement increasedfrom 0.14 to 0.46). 30,37 Another research groupfound that asking physicians and nurses to use asystematic set of questions for competence assessmentled to a high rate of agreement with expertjudgments. 38 Published question sets with goodface validity are readily available, and they shouldbe used to guide clinical assessments. 31,38 Table1 includes sample questions.Any physician who is aware of the relevant criteriashould be able to assess a patient’s competence.Indeed, treating physicians may have theadvantage of greater familiarity with the patientand with available treatment options. Psychiatricconsultation may be helpful in particularly complexcases or when mental illness is present. Althougha simple instrument to screen patients forimpaired capacity would facilitate the identificationof patients who may require more detailedassessment, to date the quest for a brief neuropsychologicalscreening instrument has not yieldedconsistent findings. However, the Mini–MentalState Examination (MMSE) has been found to correlatewith clinical judgments of incapacity, 11 andit may have some use in identifying patients at thehigh and low ends of the range of capacity, especiallyamong elderly persons with some degree ofcognitive impairment. 39,40 MMSE scores rangefrom 0 to 30, with lower scores indicating decreasingcognitive function. No single cutoff scoreyields both high sensitivity and high specificity.MMSE scores of less than 19 are highly likely tobe associated with incompetence 39,40 ; studies varyin suggesting that scores of 23 to 26 or higherare strongly indicative of competence. 11,38-40In an effort to further standardize and henceincrease the reliability and validity of competenceevaluations, several more formal assessment instrumentshave been developed. Their characteristicsand psychometric properties have been describedelsewhere. 41,42 The most widely used ofthese instruments is the MacArthur CompetenceAssessment Tool for Treatment, a structured interviewthat, unlike many other assessment instruments,incorporates information specific to a givenpatient’s decision-making situation. 43 Quantitativescores are generated for all four criteria related todecision-making capacity, but evaluators must integratethe results with other data in order to reacha judgment about competence. The high interrateragreement on these scores that has been reportedby a number of research groups 11,41,44 is usuallygreater than that reported in studies of systematicclinical assessment.The MacArthur test takes approximately 20minutes to administer and score, assuming thatthe person who administers and scores the test hasexperience with the format and scoring criteria.Given the extra time associated with the use ofassessment instruments, they would appear tohave particular value when assessment is especiallydifficult or when a case is likely to be resolvedin court, where the availability of systematicdata collected in a standard format may beuseful to a nonmedical fact finder. However, evenif scores are not generated, the use of a structuredinstrument can help guide the clinical assessmentprocess.Whatever approach to assessment is used, examinersshould first ensure that patients have beengiven the information that is relevant to makingan informed decision about their treatment. Typically,such disclosure includes the nature of thepatient’s condition, the nature and purpose of theproposed treatment, and the risks and benefits ofthe proposed treatment and of alternative treatments,including the option of no treatment at all. 1Since such disclosure cannot be presumed, eitherthe evaluator should ask a physician responsiblefor the patient’s care to disclose the relevant informationagain in the evaluator’s presence or then engl j med 357;18 www.nejm.org november 1, 2007 1837Downloaded from www.nejm.org at CHILDRENS HOSPITAL-LIB FAGAN PLAZA on November 2, 2007 .Copyright © 2007 Massachusetts Medical Society. All rights reserved.