Key result
Black individuals without co-morbidities had a lower rate of incident Alzheimer's disease compared to White individuals (HR 0.69), whereas those with co-morbidities had a higher rate, driven largely by the greater effect of hypertension.
Why the study?
Alzheimer's disease incidence is thought to be higher among Black than White individuals, prompting investigation into the roles of race and co-morbidities.
How do race and co-morbidities affect the incidence of Alzheimer's disease in the US Medicare population?
Cohort (n=11,880,906)
How do race and co-morbidities affect the incidence of Alzheimer's disease in the US Medicare population?
Hazard Ratio: 0.69 (95% CI 0.65–0.74)
The higher incidence of Alzheimer's disease in Black compared to White individuals appears to be driven by the presence of co-morbidities, particularly hypertension, rather than race alone.
Comorbidities, especially hypertension, may drive racial Alzheimer's disparities in Medicare beneficiaries; hypothesis-generating for targeted prevention research.
INTRODUCTION: Alzheimer's disease (AD) incidence is thought to be higher among Black than White individuals. METHODS: We studied the US Medicare population from 2000 to 2018. Cox regression was used to determine the roles of race and co-morbidities for AD incidence. RESULTS: We studied 11,880,906 Medicare beneficiaries, with 774,548 AD cases. Hazard ratios (HRs) by increasing numbers of co-morbidities (1-7) were 1.51, 2.00, 2.55, 3.16, 2.89, 4.77, and 5.65. Among those with no co-morbidities, Black individuals had a lower rate than those who are White (HR = 0.69), while among those with one more co-morbidities, Black individuals had a higher rate (HR = 1.19). The presence of hypertension increased AD rates by 14% for White individuals, but 69% for those who are Black. DISCUSSION: More co-morbidities was strongly associated with higher AD rates. The higher rates for Black versus White individuals was apparent only for those with co-morbidities and appears driven both by more co-morbidities, and the greater effect of hypertension. HIGHLIGHTS: Black individuals have been shown to have higher Alzheimer's disease (AD) rates than those who are White. Some co-morbidities are known to increase AD risk. Among those In Medicare data with no co-morbidities, Black individuals have less risk than those who are White. Among those with co-morbidities, Black individuals have higher rates than those who are White. Hypertension results in a much stronger increase in AD risk for Black versus White individuals.
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Steenland et al. (2022) conducted a cohort in Alzheimer's disease (n=11,880,906). Black race vs. White race was evaluated on First occurrence of a diagnosis of Alzheimer's disease (among individuals with no co-morbidities) (HR 0.69, 95% CI 0.65-0.74). Black individuals without co-morbidities had a lower rate of incident Alzheimer's disease compared to White individuals (HR 0.69), whereas those with co-morbidities had a higher rate, driven largely by the greater effect of hypertension.
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