E. Pucci et al., Information and competency for consent to pharmacologic clinical trials inAlzheimer disease: An empirical analysis in patients and family caregivers, ALZ DIS A D, 15(3), 2001, pp. 146-154
This study was undertaken to evaluate (1) what information normal and Alzhe
imer disease (AD) participants are able to manage; (2) the correlation betw
een the degree of competency and age, education and dementia scores, and th
e ability of dementia scores to predict incompetence; and (3) the capacity
to retain consent-related information. To fulfil these aims, a four-point c
ompetency rating scale (1 = incompetent, 2 = marginally competent, 3 = suff
iciently competent, and 4 = completely competent) was used in 70 patients (
Mini-Mental State Examination [MMSE] score >9; Global Deterioration Scale s
core <6) and in 40 cognitively normal caregivers. Patients Were divided int
o two subgroup., (competency ratings 1 and 2 versus 3 and 4) to calculate p
ositive and negative predictive values of MMSE and Alzheimer Disease Assess
ment Scale-cognitive (ADAScog) for absent/marginal competence. Main results
Were as follows: (1) 32.9% of AD patient, were "incompetent" (no caregiver
s), 37.1% were "marginally competent" (20% caregivers), 18.6% were "suffici
ently competent" (50%, caregivers), and 11.4% were "completely competent" (
30% caregiverss). (2) Competency ratings and age did not correlate in AD, w
hereas a negative correlation was significant in caregivers; competency rat
ings positively correlated to education in caregivers. (3) ADAScog and MMSE
were the tests most significantly correlated to competency; MMSE score bel
ow 18 had a positive predictive value of 95% and a negative predictive valu
e of 63.3%. The fact that 95% of patients with MMSE scores below 18 are inc
ompetent or marginally competent points to an urgent need for ethical proce
dures capable of creating a balance between difficulties in obtaining valid
consent and a patient's fight to benefit from advances in clinical researc
h.