Alzheimer's disease is a common cause of death among older adults. Being able to predict survival would help caregivers plan for long-term patient care needs. Characteristics that have been associated with higher mortality rates include male sex, initial dementia severity, presence of behavioral disturbances, wandering and falling, comorbid conditions, and presence of extrapyramidal signs. Larson and associates used a prospective observational study to look at the natural history of Alzheimer's disease in 521 recently diagnosed (less than one year) patients.
The medical records of patients receiving care at clinics associated with a large health maintenance organization who had memory loss, confusion, or wandering were examined for evidence of dementia by diagnostic test or prior diagnosis. Primary care physicians also could refer new patients suspected to have dementia. Patients who were determined to have newly recognized dementia were invited to participate in the study. Standardized examination and diagnostic testing were performed on all patients who agreed to participate in the study. Only patients with a probable or possible diagnosis of Alzheimer's disease were included. Mean follow-up time was 5.2 years.
Life expectancy was significantly lower in patients with Alzheimer's disease than in the general population. Younger patients and women had higher survival rates. Patients 85 years and older with gait disturbance, wandering, comorbid diabetes, and congestive heart failure had the lowest survival rate. Other characteristics that predicted shortened survival included male sex, a lower score on the Mini-Mental State Examination (MMSE), presence of extrapyramidal signs, history of falls, presence of urinary incontinence, history of ischemic cardiac disease, and history of stroke. An early decline in MMSE score (at least a 5-point decline in the first year) also was associated with a decreased survival rate.
The authors conclude that the most powerful predictors of decreased survival among patients with Alzheimer's disease were a poor score on the MMSE and increased Alzheimer's disease–related functional impairment. Patients who have a more rapid decline in cognitive performance during the first year also have a poorer prognosis. These factors, discovered by a thorough evaluation, can have prognostic value in following patients with Alzheimer's disease and planning long-term care.
In an editorial in the same journal, Covinsky and Yaffe agree that prognosis has important care implications for patients with Alzheimer's disease. Planning is appropriate to help both the patient and the caregiver, because the diagnosis of dementia is a sentinel event that heralds future deterioration. Planning for palliative care is aided by thinking of dementia as a progressive disorder.