Excess Mortality With Alzheimer Disease and Related Dementias as an Underlying or Contributing Cause During the COVID-19 Pandemic in the US

Abstract

Importance: Adults with Alzheimer disease and related dementias (ADRD) are particularly vulnerable to the direct and indirect effects of the COVID-19 pandemic. Deaths associated with ADRD increased substantially in pandemic year 1. It is unclear whether mortality associated with ADRD declined when better prevention strategies, testing, and vaccines became widely available in year 2.

Objective: To compare pandemic-era excess deaths associated with ADRD between year 1 and year 2 overall and by age, sex, race and ethnicity, and place of death.

Design, setting, and participants: This time series analysis used all death certificates of US decedents 65 years and older with ADRD as an underlying or contributing cause of death from January 2014 through February 2022.

Exposure: COVID-19 pandemic era.

Main outcomes and measures: Pandemic-era excess deaths associated with ADRD were defined as the difference between deaths with ADRD as an underlying or contributing cause observed from March 2020 to February 2021 (year 1) and March 2021 to February 2022 (year 2) compared with expected deaths during this period. Expected deaths were estimated using data from January 2014 to February 2020 fitted with autoregressive integrated moving average models.

Results: Overall, 2 334 101 death certificates were analyzed. A total of 94 688 (95% prediction interval [PI], 84 192-104 890) pandemic-era excess deaths with ADRD were estimated in year 1 and 21 586 (95% PI, 10 631-32 450) in year 2. Declines in ADRD-related deaths in year 2 were substantial for every age, sex, and racial and ethnic group evaluated. Pandemic-era ADRD-related excess deaths declined among nursing home/long-term care residents (from 34 259 [95% PI, 25 819-42 677] in year 1 to -22 050 [95% PI, -30 765 to -13 273] in year 2), but excess deaths at home remained high (from 34 487 [95% PI, 32 815-36 142] in year 1 to 28 804 [95% PI, 27 067-30 571] in year 2).

Conclusions and relevance: This study found that large increases in mortality with ADRD as an underlying or contributing cause of death occurred in COVID-19 pandemic year 1 but were largely mitigated in pandemic year 2. The most pronounced declines were observed for deaths in nursing home/long-term care settings. Conversely, excess deaths at home and in medical facilities remained high in year 2.

Figure 1.. Crude COVID-19 Pandemic-Era Excess Deaths With Alzheimer Disease and Related Dementias (ADRDs) Listed as an Underlying or Contributing Cause Between March 2020 and February 2022 in the US

Death data were obtained from the US Centers for Disease Control and Prevention WONDER Multiple Cause of Death Files. Excess deaths were defined as the difference between the observed number of deaths (orange) and the expected number of deaths (blue). The red dashed line indicates the start of vaccine rollouts. Predictions were based on best-fit auto-regressive integrated moving-average models. Shaded areas indicate 95% prediction intervals (PIs).

Figure 2.. Age-Adjusted Per-Capita Excess Deaths Associated With Alzheimer Disease and Related Dementias Between March 2020 and February 2022 in the US by Sex

We show the age-standardized monthly excess deaths (95% prediction interval) per 100 000 population by sex. Death data were obtained from the US Centers for Disease Control and Prevention WONDER Multiple Cause of Death Files. Population estimates were obtained from the US Census Bureau Population Estimates Program and Centers for Disease Control and Prevention WONDER. Excess deaths were defined as the difference between the observed number of deaths (orange) and the expected number of deaths (blue). The red dashed line indicates the start of vaccine rollouts (mid-December 2020). Predictions were based on best-fit auto-regressive integrated moving-average models. Shaded areas indicate 95% prediction intervals.

Figure 3.. Age-Adjusted Per-Capita Excess Deaths Associated With Alzheimer Disease and Related Dementias Between March 2020 and February 2022 in the US by Race and Ethnicity

Death data were obtained from the US Centers for Disease Control and Prevention WONDER Multiple Cause of Death Files. Population estimates were obtained from the US Census Bureau Population Estimates Program and Centers for Disease Control and Prevention WONDER. Excess deaths were defined as the difference between the observed number of deaths (orange) and the expected number of deaths (blue). Predictions were based on best-fit auto-regressive integrated moving-average models. The red dashed line indicates the start of vaccine rollouts. Shaded areas indicate 95% prediction intervals.

Figure 4.. Crude Excess Deaths Associated With Alzheimer Disease and Related Dementias Between March 2020 and February 2022 in the US by Place of Death

Death data were obtained from the US Centers for Disease Control and Prevention WONDER Multiple Cause of Death Files. Excess deaths were defined as the difference between the observed number of deaths (orange) and the expected number of deaths (blue). The red dashed line indicates the start of vaccine rollouts. Predictions were based on best-fit auto-regressive integrated moving-average models. Death rates were not age adjusted because we did not have information about the population size in each place of death.