Summary: An estimated 13.6% of deaths in the U.S could be attributed to dementia. The number is 2.7 times higher than the official reported dementia-related deaths. The underestimation varies greatly by race, with 7.1 times more older Black adults, and 4.1 times more Hispanic adults, dying from dementia that public records indicate.
Source: Boston University School of Medicine
Dementia may be an underlying cause of nearly three times more deaths in the U.S. than official records show, according to a new Boston University School of Public Health (BUSPH) study.
Published in the journal JAMA Neurology, the study estimates that 13.6% of deaths are attributable to dementia, 2.7 times more than the 5.0% of death certificates that indicate dementia as an underlying cause of death. Understanding what people die of is essential for priority setting and resource allocation,” says study lead author Dr. Andrew Stokes, assistant professor of global health at BUSPH.
“In the case of dementia, there are numerous challenges to obtaining accurate death counts, including stigma and lack of routine testing for dementia in primary care,” he says. “Our results indicate that the mortality burden of dementia may be greater than recognized, highlighting the importance of expanding dementia prevention and care.”
The researchers found that the underestimation varies greatly by race, with 7.1 times more Black older adults, 4.1 times more Hispanic older adults, and 2.3 times more white older adults dying from dementia than government records indicate. Dementia related deaths were also underreported more for men than women, and more for individuals without a high school education. Previous research has shown that dementia is disproportionately common among older adults who are Black, male, and/or have less education.
“In addition to underestimating dementia deaths, official tallies also appear to underestimate racial and ethnic disparities associated with dementia mortality. Our estimates indicate an urgent need to realign resources to address the disproportionate burden of dementia in Black and Hispanic communities,” Stokes says.
The researchers used data from a nationally-representative cohort of 7,342 older adults in the Health and Retirement Study (HRS), which gathers data from individuals starting when they move into nursing homes. For the current study, the researchers used data from older adults who entered the cohort in 2000 and followed them up to 2009, analyzing the association between dementia and death when adjusting for other variables including age, sex, race/ethnicity, education level, region of the U.S., and medical diagnoses.
“These findings indicate that dementia represents a much more important factor in U.S. mortality than previously indicated by routine death records,” says study senior author Dr. Eileen Crimmins, professor and AARP Chair in Gerontology at the University of Southern California Leonard Davis School of Gerontology and a co-investigator on the Health and Retirement Study.
Importance Vital statistics are the primary source of data used to understand the mortality burden of dementia in the US, despite evidence that dementia is underreported on death certificates. Alternative estimates, drawing on population-based samples, are needed.
Objective To estimate the percentage of deaths attributable to dementia in the US.
Design, Setting, and Participants A prospective cohort study of the Health and Retirement Study of noninstitutionalized US individuals with baseline exposure assessment in 2000 and follow-up through 2009 was conducted. Data were analyzed from November 2018 to May 2020. The sample was drawn from 7489 adults aged 70 to 99 years interviewed directly or by proxy. Ninety participants with missing covariates or sample weights and 57 participants lost to follow-up were excluded. The final analytic sample included 7342 adults.
Exposure Dementia and cognitive impairment without dementia (CIND) were identified at baseline using Health and Retirement Study self- or proxy-reported cognitive measures and the validated Langa-Weir score cutoff.
Main Outcomes and Measures Hazard ratios relating dementia and CIND status to all-cause mortality were estimated using Cox proportional hazards regression models, accounting for covariates, and were used to calculate population-attributable fractions. Results were compared with information on cause of death from death certificates.
Results Of the 7342 total sample, 4348 participants (60.3%) were women. At baseline, 4533 individuals (64.0%) were between ages 70 and 79 years, 2393 individuals (31.0%) were between 80 and 89 years, and 416 individuals (5.0%) were between 90 and 99 years; percentages were weighted. The percentage of deaths attributable to dementia was 13.6% (95% CI, 12.2%-15.0%) between 2000 and 2009. The mortality burden of dementia was significantly higher among non-Hispanic Black participants (24.7%; 95% CI, 17.3-31.4) than non-Hispanic White participants (12.2%; 95% CI, 10.7-13.6) and among adults with less than a high school education (16.2%; 95% CI, 13.2%-19.0%) compared with those with a college education (9.8%; 95% CI, 7.0%-12.5%). Underlying cause of death recorded on death certificates (5.0%; 95% CI, 4.3%-5.8%) underestimated the contribution of dementia to US mortality by a factor of 2.7. Incorporating deaths attributable to CIND revealed an even greater underestimation.
Conclusions and Relevance The findings of this study suggest that the mortality burden associated with dementia is underestimated using vital statistics, especially when considering CIND in addition to dementia.