[Predictors of long-term institutionalization in patients with Alzheimer's disease: role of caregiver burden]

The decision of long-term institutionalization of patients with Alzheimer's disease (AD) is based on multiple patients' and caregivers' characteristics. It is very important to find out factors associated with institutionalization for the timely institutionalization, i.e. for the prevention of premature institutionalization. Among those factors, caregiver burden is reportedly one of the most important factors in Europe and North America. However, no studies have been carried out in Japan. In order to address this issue, we studied outcome of patients with AD.Subjects were 211 patients who fulfilled the criteria of the National Institute of Neurological Disease and Stroke/Alzheimer's Disease and Related Disorders Association for probable AD. Diagnosis of AD was made through extensive examinations including MRI and PET/SPECT of the brain. The patients included 149 women and 62 men; the mean age was 73.1 +/- 8.0 (SD) years. The Japanese version of Zarit Caregiver Burden Interview (ZBI), which is a validated tool for assessment of the burden of caregivers for dementia patients, was used to evaluate caregivers' burden through the interview of a principal caregiver by trained nurses. Cognitive, functional, and neuropsychiatric impairments were assessed with standardized instruments of the Mini-Mental State Examination (MMSE), Hyogo Activities of Daily Living Scale (HADLS), Neuropsychiatric Inventory (NPI), respectively. We annually sent a questionnaire to the caregivers to collect information on the patients' status. It included questions whether and when they died or were institutionalized and whether they had used formal social supports such as home care, day care, and respite care services.Time to death or institutionalization.One-hundred and fifty subjects were followed for at least one year and 51 of them met either end point. The Cox proportional hazard model demonstrated that the baseline caregiver burden was a significant predictor of the end point even after controlling possible confounders. Among these, the use of day care and home care services during the course were significant protective factors. The baseline cognitive and functional disturbances but not neuropsychiatric manifestations were significantly associated with the end point.The caregiver burden is a significant predictor for the death or institutionalization of the patients with AD. The caregiver education which decrease the caregiver burden and prompt the usage of the social care services are necessary to protect premature institutionalization.