Temporal and Geographic Variation in the Incidence of Alzheimer's Disease Diagnosis in the US between 2007 and 2014

Abstract

OBJECTIVES Our aim was to describe the incidence of Alzheimer's disease (AD) in the United States, overall and by geographic region. DESIGN We conducted retrospective analyses of administrative claims data for a 5% random sample of US Medicare beneficiaries aged 65 years or older. AD incidence, defined as a diagnosis for AD (International Classification of Disease, Ninth Revision, Clinical Modification code 331.0×) in a given year, with no AD diagnosis in the beneficiary's entire medical history, was estimated for each calendar year between 2007 and 2014. Beneficiaries were required to be enrolled in Medicare for the calendar year of evaluation as well as the preceding 12 months. In addition, a cross‐sectional assessment of geographic variation in AD incidence was conducted for 2014. For each population area (specifically, core‐based statistical area, as defined by the US Census Bureau), AD incidence was estimated overall, as well as adjusted for differences in underlying patient demographics and metrics of access to care and quality of care. Changes in AD incidence from 2007 were also estimated. SETTING US fee‐for‐service Medicare. Participants US Medicare beneficiaries aged 65 years or older with no history of AD. RESULTS Overall, the diagnosed incidence of AD decreased over time, from 1.53% in 2007 to 1.09% in 2014; trends were similar for most population areas. In 2014, the rates of AD incidence ranged from 0% to more than 3% across population areas, with the highest observed incidence rates in areas of the Midwest and the South. Statistical models explain little of the geographic variation, although following adjustment, the incidence rates increased the most (in relative terms) in rural areas of western states. CONCLUSION Our findings are consistent with previously reported estimates of incidence of AD in the United States and its recent declining trend. Additionally, the study highlights the considerable geographic variation in the incidence of AD in the United States and suggests that further research is needed to better understand the determinants of this geographic variation. J Am Geriatr Soc 68:346–353, 2020

Geographic disparities in mortality from Alzheimer's disease and related dementias

“…The identified patterns were stable over the 1999–2018 period. Our assessments of the geographic patterns of AD mortality are consistent with previous analyses of geographic disparities in AD/ADRD incidence, 12 prevalence, 13 and mortality, 3 which detected considerable geographic variations in these measures. Kirson et al 12 found that statistical regression‐based models with demographic, socioeconomic, and access‐to‐care/quality‐of‐care predictors could explain a maximum of 30% of the variation in the observed rates of incident AD diagnoses.…”

“…Our assessments of the geographic patterns of AD mortality are consistent with previous analyses of geographic disparities in AD/ADRD incidence, 12 prevalence, 13 and mortality, 3 which detected considerable geographic variations in these measures. Kirson et al 12 found that statistical regression‐based models with demographic, socioeconomic, and access‐to‐care/quality‐of‐care predictors could explain a maximum of 30% of the variation in the observed rates of incident AD diagnoses. Gillum et al 3 documented the difference between WA and NY in AD mortality and suggested several mechanisms of generating such disparities involving variations of risk factor diseases, interactions between their incidence, survival, diagnostic practice, and completion of death certificates for future research.…”

Expanding the scope of health disparities research in Alzheimer's disease and related dementias

“…Analysis of fee-for-service records from the Medicare system showed that the highest incidence rates of AD were observed in the Midwest and the South of the United States. 68 County-level variation within these regions has also been observed, thus underscoring the need for interventions and public health efforts tailored to local communities. 69 Furthermore, it has been shown that Black and White residents born in the Stroke Belt region within the United State are at higher risk of dementia-related mortality than those born in other states, even for people who moved out of this region.…”

“…The size of both race/ethnicity and sex‐related disparities can be strongly influenced by the current and historical characteristics of a discrete geographic region. Analysis of fee‐for‐service records from the Medicare system showed that the highest incidence rates of AD were observed in the Midwest and the South of the United States 68 . County‐level variation within these regions has also been observed, thus underscoring the need for interventions and public health efforts tailored to local communities 69 .…”

The role of geographic information system and global positioning system in dementia care and research: a scoping review

“…Most maps were applied to visualize the spatial and temporal patterns of dementia/Alzheimer's mortality [49,50,55,[68][69][70][71][72][73][74][75][76][77][78]] and hospital admission rates [79]. Some visualized spatial distribution of birthplace of dementia patients [80,81], the area with high concentration [82], incidents of missing patients with dementia [83], dementia risk/rate [4,12,57,[84][85][86][87][88][89][90][91][92][93], hospice use [94], opioid use [95], and antipsychotic drug use [15]. Some studies used mapping in preparing exposure data [67], arsenic concentrations [96], ozone levels [97], spatial distributions of air pollutants [98] and ranking countries in medical tourism [56].…”