Objective: To detect prognostic factors in very old demented subjects with Alzheimer's disease (AD), vascular dementia (VaD), and other types of dementia (OD).
Design: Follow-up clinical examinations of dementia patients from a population-based study after 3- and 7-year intervals.
Setting and participants: In an established population aged 75 years and older in Stockholm, Sweden, there were 133 cases of AD, 52 of VaD, and 38 of OD.
Main outcome measures: Predictors of survival at 3- and 7-year follow-up examinations were evaluated by Cox proportional hazard models. Progression was measured as the annual rate of change in Mini-Mental State Examination (MMSE) scores. Linear models were used to evaluate predictors of progression.
Results: Older age, male gender, low education, comorbidity, and functional disability predicted shorter 7-year survival in the 223 prevalent dementia cases. Other factors, including type of dementia, dementia severity, and duration of the disease were not significant. The average rate of cognitive decline in the 81 mild to moderate demented subjects who survived 3 years was 2.4 MMSE points per year. Type of dementia (AD vs OD), higher baseline cognitive function, and greater functional disability predicted faster decline. Despite similar survival probability, predictors of death varied as a function of dementia type: Older age (for AD and VaD), comorbidity (for AD and OD), and functional dependency (for VaD). In AD, prognostic factors were similar to those described for the combined dementia groups, with the exception of an accelerated cognitive decline among women.
Conclusions: Although methodological difficulties exist, it is possible to identify demented subjects with worse prognoses (shorter survival and faster cognitive decline) by using clinical and demographic data. Clinicians and healthcare planners should be aware of the potential usefulness of functional dependence as a prognostic indicator. Finally, the need for careful clinical examinations of demented subjects is stressed by the increased mortality found among those demented who are also affected by other chronic conditions.