For the study, the researchers used the TriNetX Analytics Platform, which provides clinical data and analytics, to access anonymous electronic health records of over 95 million people who made inpatient and outpatient visits at nearly 70 healthcare organizations. The participants came from 50 states and represented diverse geographic, age, race/ethnicity, income, and insurance groups.
Next, the researchers narrowed the list of participants to a group of 6.2 million adults ages 65 and older who had received medical treatment between February 2020 and May 2021 and had no prior diagnosis of Alzheimer’s disease.
Researchers then divided the participants into two groups: One group contracted COVID-19 between February 2020 and May 2021, and the other did not contract the disease during that time. About 5.8 million participants were in the group with no infection, while more than 400,000 had COVID-19.
The researchers looked at the risk for a new diagnosis of Alzheimer’s disease in the two groups as well as in three age groups (65 to 74, 75 to 84, and age 85 and older), men and women, and in Black, white, and Hispanic racial/ethnic groups.
Gender and age were the same in the COVID-19 cohort and the non-COVID-19 cohort. However, the group that contracted COVID-19 did include more Hispanic and Black participants and had a “higher prevalence of adverse socioeconomic determinants of health and comorbidities,” according to the study.
Cohorts were propensity-score matched for demographics, adverse socio-economical determinants of health, including problems with education, occupational exposure, physical, social and psychosocial environment, and known risk factors for Alzheimer’s disease. The researchers used a Kaplan-Meier analysis to estimate the likelihood of a new diagnosis of Alzheimer’s disease within 360 days after a COVID-19 diagnosis.
Researchers used Cox’s proportional hazards model to compare matched cohorts using hazard ratios and 95% confidence intervals.