Is the degree of cognitive impairment in patients with Alzheimer's disease related to their capacity to appoint an enduring power of attorney?
1 Medical Student University of Birmingham Medical School, Edgbaston, Birmingham B15 2TT, UK
2 Senior Lecturer in Psychiatry Queen Elizabeth Psychiatric Hospital, Mindelsohn Way, Edgbaston, Birmingham B15 2QZ, UK
Address correspondence to: Rebecca Gregory. Email: rhg268{at}bham.ac.uk
Background Clinicians are often asked to retrospectively assess a patient's capacity to create an Enduring Power of Attorney (EPA). This study will investigate if capacity to create an EPA is significantly related to the degree of cognitive impairment in Alzheimer patients, and whether Mini Mental State Examination score (MMSE) is a good predictor of a patient's capacity. It also considers if socio-demographic factors are related to a patient's capacity to create an EPA.
Methods Participants with a DSM-IV diagnosis of Alzheimer's disease were recruited from the Old Age Psychiatric service at the Queen Elizabeth Psychiatric Hospital, Birmingham, UK. A cognitive assessment of each patient was performed using the MMSE, followed by two independent assessments of their capacity to create an EPA made using a semi-structured interview.
Results There was a significant association between level of cognitive impairment and capacity to create an EPA: 
2 = 35.15 (P<0.0001). MMSE score significantly predicted capacity status (OR=1.6, 95% CI 0.863–0.979). Optimal sensitivity (86.6%, CI 67.4–95.5%) and specificity (82.2% CI 67.4–91.5%) were obtained using a cutoff MMSE score of 18. Positive predictive value (PPV): 75.8% (95% CI 57–88%), negative predictive value (PNV): 90.2% (CI 76–97%). No socio-demographic factors were significantly associated with capacity to create an EPA.
Conclusions The MMSE could be used as a screening tool to help inform a clinical capacity assessment in patients with Alzheimer's disease. It is important that patients always undergo individual clinical assessments where possible, but in situations where direct assessment is not possible MMSE score could be used to aid retrospective assessments of capacity to create an EPA.
Keywords: capacity, enduring power of attorney, dementia, Alzheimer's disease, cognitive impairment, mini-mental state examination (MMSE)
Received 6 September 2006; accepted in revised form 3 May 2007.