Risk of Alzheimer’s Disease Following Influenza Vaccination: A Claims-Based Cohort Study Using Propensity Score Matching

Abstract

Background: Prior studies have found a reduced risk of dementia of any etiology following influenza vaccination in selected populations, including Veterans and patients with serious chronic health conditions. However, the effect of influenza vaccination on Alzheimer’s disease (AD) risk in a general cohort of older US adults has not been characterized. Objective: To compare the risk of incident AD between patients with and without prior influenza vaccination in a large US claims database. Methods: Deidentified claims data spanning September 1, 2009 through August 31, 2019 were used. Eligible patients were free of dementia during the 6-year look-back period and≥65 years old by the start of follow-up. Propensity-score matching (PSM) was used to create flu-vaccinated and flu-unvaccinated cohorts with similar baseline demographics, medication usage, and comorbidities. Relative risk (RR) and absolute risk reduction (ARR) were estimated to assess the effect of influenza vaccination on AD risk during the 4-year follow-up. Results: From the unmatched sample of eligible patients (n = 2,356,479), PSM produced a sample of 935,887 flu–vaccinated-unvaccinated matched pairs. The matched sample was 73.7 (SD, 8.7) years of age and 56.9% female, with median follow-up of 46 (IQR, 29–48) months; 5.1% (n = 47,889) of the flu-vaccinated patients and 8.5% (n = 79,630) of the flu-unvaccinated patients developed AD during follow-up. The RR was 0.60 (95% CI, 0.59–0.61) and ARR was 0.034 (95% CI, 0.033–0.035), corresponding to a number needed to treat of 29.4. Conclusion: This study demonstrates that influenza vaccination is associated with reduced AD risk in a nationwide sample of US adults aged 65 and older.

Associations of Antihypertensive Medication Consumption and Drug-Drug Interaction with Statin and Metformin with Reduced Alzheimer's Disease and Related Dementias Risk among Hypertensive Patients with Mild Cognitive Impairment using High Volume Claims Data

“…("WHO Collaborating Centre for Drug Statistics Methodology, ATC classification index with DDDs, 2023" : https://www.whocc.no/atc_ddd_index/) Hypertension (ICD-9: 491.x, 492.x, 496; ICD-10: J41.x, J42, J43.2, J43.8, J43.9, J44.x) is defined as having two or more outpatient/inpatient diagnosis of elevated blood pressure on different days within the same 24-month in follow-up period. (Bukhbinder et al, 2022) Antihypertensive medications (AHMs)…”

A Review of the Recent Advances in Alzheimer’s Disease Research and the Utilization of Network Biology Approaches for Prioritizing Diagnostics and Therapeutics

“…Other interventions include underlying-disease management (e.g., hypertension, diabetes, dyslipidemia, depression, and hearing loss), as stated in WHO guidelines [ 408 ]. More studies should assess the relationship between vaccines and AD; it was found that flu vaccines reduce the risk of AD development [ 409 ]. However, the protective mechanisms have not yet been elucidated.…”

Human Vaccines & immunotherapeutics: News, June 2022

“…Elderly who received the seasonal influenza vaccine were 40% less likely to develop Alzheimer’s disease (AD) in the next 4 years than their unvaccinated peers, according to a retrospective study of almost 2 million US adults aged ≥65 years old. 3 The vaccinated and unvaccinated cohorts, which were matched for their AD propensity at baseline, reported a 5.1% and 8.5% incidence of AD, respectively, at follow-up. The mechanism of action for influenza vaccine to affect AD is unknown.…”