Mortality rates in community-dwelling Tanzanians with dementia and mild cognitive impairment: A 4-year follow-up study

Abstract

Background: we have previously conducted a community-based prevalence study of dementia in older adults living in the rural Hai district of Tanzania. The aim of this study was to record mortality rates at 4 years post-diagnosis, of those with dementia, mild cognitive impairment (MCI) and no cognitive impairment.Methods: during Phase I of the prevalence study, 1,198 people aged 70 years and over were screened, and a stratified sample of 296 was assessed for the presence of dementia or MCI in Phase II. Seventy-eight people had dementia and 46 had MCI. Four years after diagnosis, we attempted to follow-up all those seen in Phase II and record all deaths.Results: of the 296, follow-up data were available for 287 (97.0%), including 77 with dementia and 45 with MCI. Of the 172 with no cognitive impairment, 165 (95.9%) were followed up and a sample of 89 people selected as representative of the background population. Forty-eight people with dementia (62.3%), 19 with MCI (42.2%) and 11 with no cognitive impairment (12.4%) had died at 4-year follow-up. After adjusting for the effects of age, gender and education, the hazard ratio was 6.33 (95% CI 3.19-12.58) for dementia and 3.57 (95% CI 1.64-7.79) for MCI relative to people with no cognitive impairment. Mortality rates were highest in those with vascular dementia.Conclusion: dementia and MCI were associated with excess mortality relative to those with no cognitive impairment.