Mortality in elderly Canadians with and without dementia - A 5-year follow-up

Objectives: Based on the national Canadian Study of Health and Aging (CSHA) , to compare 5-year overall mortality and causes of death in elderly with a nd without dementia. To determine how frequently dementia was mentioned on the death certificate. Methods: For people who underwent a clinical examina tion in 1991 (n = 2,923), overall and cause-specific mortality rate ratios were calculated by dementia status (AD; vascular dementia; other dementias/ other cognitive impairment; and normal cognition), age group (65 to 74, 75 to 84, 85+ years), and sex, using the Canadian general population as the re ference. Similar rate ratios were calculated for people in the community wh o screened negative for cognitive impairment and who did not undergo a clin ical examination (n = 7,340), Among elderly diagnosed as having AD or vascu lar dementia through the CSHA and who later died, it was determined how fre quently dementia was recorded on the death certificate. Results: The subgro up without cognitive dysfunction had a survival rate similar to that of the overall Canadian population except in the oldest age group, where the surv ival rate was better than that of the general population, which includes pe ople with dementia. People in the three groups with cognitive impairment ha d a poorer survival in all age/sex groups than those without cognitive impa irment and the general Canadian population. The most common causes of death in all groups were from vascular diseases. People with vascular dementia h ad the highest relative mortality rates for heart and cerebrovascular disea se. Most of the AD groups also had high relative vascular system mortality rates. Among patients clinically diagnosed with AD, only 14.3% had any deme nting illness recorded as the underlying cause of death; 41.8% had any deme nting illness recorded anywhere on the death certificate. For vascular deme ntia, the corresponding numbers were 5.8% and 23.3%. Conclusions: Elderly w ith dementia have clearly increased mortality rates relative to elderly wit hout cognitive impairment in all age/sex categories. People with vascular d ementia have a particularly poor prognosis. Studies of AD and vascular deme ntia using death certificate data will grossly underestimate the proportion s of elderly with these diseases.