Aim: To adapt the Quality of Life in Alzheimer's Disease (QOL-AD) scale to Spanish, as well as to evaluate its reliability and validity in Mexico.
Subjects and methods: The study involved a sample of 114 patients diagnosed with Alzheimer, vascular and mixed-type dementia, according to the criteria of the National Institute for Neurological and Communicative Disorders/Stroke-Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA), the National Institute of Neurological Disorders and Stroke/Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN) and the Alzheimer's Disease Diagnostic and Treatment Centers (ADDTC), respectively. Their primary caregivers (n = 114) and a control group (n = 30) of persons aged 60 or over without dementia and their closest relatives were also evaluated.
Results: The total group with dementia obtained a mean age and a standard deviation of 80.15 +/- 7.13. The Folstein minimental test was 18.55 +/- 4.99. We obtained a Cronbach's alpha of 0.88 for the patient version of the QOL-AD (QOL-ADp) and 0.82 for the caregiver version of the QOL-AD (QOL-ADc). The test-retest yielded an intraclass correlation coefficient of 0.9 (p < 0.001; 95% confidence interval, CI 95% = 0.58-0.91) for the QOL-ADp and 0.81 (p < 0.001; CI 95% = 0.78-0.95) for the QOL-ADc. Moreover, the QOL-ADp showed a significant correlation with the geriatric depression scale (r = -0.73; p < 0.001) and with the neuropsychiatric inventory (r = -0.44; p < 0.001). With the QOL-ADc, these correlations were r = -0.5 (p < 0.001) and r = -0.3 (p < 0.001), respectively. Both versions of the QOL-AD were able to distinguish between the group of subjects with dementia and the control group.
Conclusions: The QOL-AD yielded satisfactory results in terms of internal and external reliability, validity between measurements and between known groups. Thus, we can recommend its use to evaluate the quality of life of patients with dementia.