Evaluation of the validity and reliability of the alzheimer disease-related quality of life assessment instrument

The Alzheimer Disease-related Quality of Life (ADRQL) instrument was developed to assess health-related quality of life in people with AD using assessments from family caregivers or professional staff. Validity and reliability of the ADRQL in its original form and a revised version are assessed in a sample consisting of persons in 3 residential settings (community, assisted living, nursing home). The ADRQL exhibits good item-internal consistency (67.5% of items met 0.40 standard); high correlation of items to hypothesized scales (85% of items met criteria for 4 of 5 subscales and the overall instrument); a good range of scores (21.6 to 100 for total sample revised instrument); very low missing data; and internal-consistency reliability coefficients exceeding the minimum reliability standard for group comparisons (0.86 for total scores; range of 0.56 to 0.83 for subscales). In a community sample, the ADRQL discriminates between groups and is responsive over time in hypothesized directions. Characteristics of caregiver raters (community sample) including demographics and self-rated health were largely unrelated to scores. The results support the use of the ADRQL to evaluate health-related quality of life in persons with AD across various care settings and various stages of the disease. Modest correlations with cognitive and functional disability levels suggest that the ADRQL provides insight into other important dimensions of life experience in persons with dementia. The revised version has improved measurement properties and is recommended for use over the original.