Neurologic Disorders More Likely After Influenza vs COVID-19 Hospitalization

Patients hospitalized for influenza vs those hospitalized for COVID-19 had a higher risk for subsequent neurologic diagnoses including migraine, epilepsy, neuropathies, movement disorders, stroke, and dementia, according to study results published in Neurology.

Previous research has identified long-term neurologic effects in patients who had COVID-19 possibly due to the virus’s neurotropic nature. Acute infection can cause complications like stroke and encephalopathy, increasing mortality risk. Studies indicate a higher risk for neurologic diagnoses post-COVID-19 compared to influenza, prompting further investigation into post-infection neurologic care. To elucidate this relationship, researchers assessed the burden of neurologic care 1-year after COVID-19 infection compared to influenza.

The retrospective cohort study included electronic medical data from the TriNetX Research Network comprising 60 health organizations. Participants were adults aged 18 and older during the index event, with complete data on exposure, covariates, and outcomes.

Patients were followed for up to 1 year after the index event, which was defined as hospitalization for either COVID-19 or influenza. Study endpoints included health care encounters associated with International Classification of Diseases (ICD)-10 codes for neurologic conditions, including migraine, epilepsy, stroke, neuropathy, movement disorders, and dementia. The researchers created a composite of the diagnoses, termed “incident neurologic diagnoses,” and conducted 1:1 propensity score matching based on various demographic and clinical factors.

The analysis included a cohort of 77,272 individuals (mean age, 51; women, 57.7%; White, 41.5%) diagnosed with COVID-19 and an equally sized group of 77,272 persons diagnosed with influenza, matched based on propensity scores.

Compared with patients diagnosed with influenza, those diagnosed with COVID-19 had a lower risk for subsequent care for all neurologic conditions analyzed:

• migraine (hazard ratio [HR], 0.645; 95% CI, 0.604–0.687),
• epilepsy (HR, 0.783; 95% CI, 0.727–0.843),
• neuropathies (HR, 0.567; 95% CI, 0.532–0.604),
• movement disorders (HR, 0.644′ 95% CI, 0.598–0.693),
• stroke (HR, 0.904; 95% CI, 0.845–0.967), and
• dementia (HR, 0.931; 95% CI, 0.870–0.996).

In a follow-up analysis comparing incident neurologic diagnoses, 60,435 individuals with COVID-19 were paired with an equal number of patients with influenza patients, all without previous neurologic conditions. The findings show that 2.79% of the COVID-19 cohort experienced incident neurologic diagnoses, compared to 4.91% in the influenza cohort.

Utilizing adjusted Cox regression models, the analysis highlighted a significantly lower risk of developing new neurologic conditions among those with COVID-19 (HR 0.618, 95% CI 0.582–0.657) compared with patients with influenza.

“These results are contrary to our hypothesis that the burden of neurologic care and incident neurologic diagnoses would be higher in the year after COVID-19 compared with that after influenza,” the researchers noted.

The study’s limitations stem from its dependence on ICD codes to identify outcomes, analysis confined to a single healthcare system, potential selection bias in including patients, and the dataset’s limited national representation, which restricts its generalizability.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.