December 06, 2019
1 min read

Alzheimer's incidence varies significantly by location

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Urvi Desai

Research published in Journal of the American Geriatrics Society highlighted significant geographic variation in the incidence of Alzheimer’s disease in the United States.

“In order to better manage patients with Alzheimer’s disease and related disorders, it is important to properly identify and diagnose their condition," Urvi Desai, PhD, of Analysis Group Inc. in Boston, told Healio Psychiatry. "Our paper suggests that there is still a lot we don’t understand about the factors contributing to an incident diagnosis, and that the interplay of risk factors, access to care and quality of care need to be further studied at the local level to inform policy discussions."

Desai and colleagues obtained a 5% random sample of Medicare beneficiaries aged 65 years or older and conducted retrospective analyses of their administrative claims data. They defined Alzheimer’s disease incidence as a diagnosis according to the ICD-9 in a given year and excluded patients with a prevalent Alzheimer’s disease diagnosis before the measurement year. Between 2007 and 2014, they estimated disease incidence, and for 2014, they conducted a cross-sectional assessment of geographic variation in disease incidence.

The researchers found that the overall diagnosed incidence of Alzheimer’s disease decreased from 1.53% in 2007 to 1.09% in 2014, with similar trends for most population areas. Rates of incidence in 2014 ranged from 0% to more than 3% across population areas. Areas of the Midwest and South experienced the highest observed incidence rates. Desai and colleagues noted that little of the geographic variation can be explained by statistical models; however, after adjustment, incidence rates in relative terms increased the most in rural areas of western states.

"The declining trend in incident Alzheimer’s disease diagnosis over time is consistent with other reports," Desai said. "However, the finding that the patient demographics and health-system-related measures explain only a small portion of the regional variation in diagnosis rates suggests that other, non-observed factors such as physician practice and patient and caregiver preferences might play a critical role in the detection of Alzheimer’s disease.” – by Joe Gramigna

Disclosures: Desai reports being employed by Analysis Group Inc., which received funding from Eli Lilly and Company. Please see the study for all other authors’ relevant financial disclosures.