Self-Rated and Caregiver-Rated Quality of Life in Alzheimer Disease with a Focus on Evolving Patient Ability to Respond to Questionnaires: 5-Year Prospective ALSOVA Cohort Study

Objective: To examine and compare self-rated and caregiver-rated measures of quality of life (QoL) in relation to disease progression in patients with very mild or mild Alzheimer disease (AD) and at what disease stage patient's ability to respond to QoL questionnaires with or without assistance begins to diminish. Methods: 236 patients with very mild or mild AD and their family caregivers from three Finnish hospital districts participated in this prospective, longitudinal study with 5 years of follow-up. Three patient-reported instruments were used to assess QoL (the generic 15D, the Quality of Life in Alzheimer Disease [QoL-AD] questionnaire, and a visual analogue scale) as well as one caregiver-rated assessment of patient QoL (QoL-AD). AD severity was evaluated with the Clinical Dementia Rating Scale - Sum of Boxes (CDR-SOB). Results: All self-and caregiver-rated QoL estimates correlated with AD severity. The self-and caregiver-rated QoL scores began to diverge even with very mild cognitive impairment after CDR-SOB reached 4, the value that corresponds with a Mini-Mental State Examination (MMSE) score of 25-30. Patients also began to need assistance in responding to questionnaires at very early stages of AD (CDR-SOB score: 4-6). Furthermore, their ability to respond to QoL questionnaires with or without assistance declined after CDR-SOB reached 11 points, a value that correlates with an early moderate stage of AD and MMSE score of 11-20. Conclusions: AD patients' self-rated QoL ratings are much more insensitive to disease progression than caregiver ratings.