Addressing the bias problem in the assessment of the quality of life of patients with dementia: determinants of the accuracy and precision of the proxy ratings.
OBJECTIVE
We aimed to examine the discrepancy between patients and caregivers' ratings of quality of life in terms of accuracy and precision, and identify factors associated with it, in order to facilitate the use of this scale as dementia progresses.


METHODS
Cross-sectional analytic study.


METHODS
Day care centres.


METHODS
Community-living patients with Alzheimer's disease in early or moderate stage and their principal caregivers.


METHODS
PARTICIPANTS rated patients' quality of life using DEMQOL. The discrepancy was assessed using the individual difference score and the residuals for each domain of DEMQOL. The scores on Mini-Mental State Examination, Geriatric Depression Scale, Neuropsychiatric Inventory, Clinical Insight Rating Scale, Cumulative Illness Rating Scale, Health Utilities Index Mark 3 and Zarit Burden Interview were considered as possible predictors of the discrepancy.


RESULTS
A total of 276 subjects participated in the study (138 patients with Alzheimer's disease and their caregivers). Discrepancy measured by individual difference score was lower than that measured by the residuals. Burden and mood-related symptoms explained the positive differences and residuals, while pain, self-perceived depression and cognition determined the negative ones.


CONCLUSIONS
Differences exist between patients and caregivers' perceptions about subjective states. The evaluations of each informant seem to be influenced by their own emotional state and the inner experience of the effects of the disease. Caregivers' ratings on DEMQOL could be useful to monitor the efficacy of any treatment whenever burden is low and patients have no great physical or emotional suffering.
Maria Gomez-Gallego, Campus de Los Jerónimos, 30107 Murcia, Telephone: (+34) 968 27 88 00, Email: mgomezg@um.es.
M
M
Gomez-Gallego
J
J
Gomez-Garcia
E
E
Ato-Lozano
D000339:Affect; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications / Q000523:psychology*; D015982:Bias; D017028:Caregivers / Q000523:psychology*; D003071:Cognition; D003430:Cross-Sectional Studies; D003863:Depression / Q000150:complications / Q000175:diagnosis / Q000523:psychology; D018450:Disease Progression; D005260:Female; D015577:Geriatric Assessment / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010361:Patients / Q000523:psychology*; D011788:Quality of Life / Q000523:psychology*; D057566:Self Report