Severe influenza confers greater risk of neurological disorders than covid-19

Emphasis

According to the results of a large study, hospitalization for influenza is associated with a higher risk of subsequent neurological disorders, such as migraine, stroke and epilepsy, than hospitalization for covid-19.

Methodology

• The researchers used health claims data to compare 77,300 individuals who were hospitalized with Covid-19 to 77,300 people hospitalized with influenza. The study did not analyze individuals with long Covid-19.

• In the final sample of 154,500 participants, the average age was 51 years, and more than half of the individuals (58%) were female.

• Researchers followed participants from both cohorts for a year to see how many would need medical care for six of the most common neurological disorders: migraines, epilepsy, stroke, neuropathy, dementia and movement disorders.

• If participants had experienced one of these neurological disorders prior to the original hospitalization, the primary outcome would involve subsequent visits for neurological diagnosis.

Main results

• Participants hospitalized with Covid-19 (when compared to the group with influenza) were significantly less likely to need treatment for migraines in the following year (2.0% versus 3.2%), epilepsy (1.6% vs. 2.1%), neuropathy (1.9% vs. 3.6%), movement disorders (1.5% vs. 2.5%), stroke (2.0% vs. 2.4%) and dementia (2.0% vs. 2.3%), with P < 0.001 for all comparisons.

• After adjusting for age, sex and other health problems, the researchers found that individuals in the group with Covid-19 had a 35% lower risk of receiving care for migraines, a 22% lower risk for epilepsy and a 44% lower risk for neuropathy, when compared to individuals in the influenza group. They also had a 36% lower risk of receiving care for movement disorders, 10% lower risk for stroke (all with P < 0.001) and 7% lower for dementia (P = 0.0007).

• Among participants without pre-existing neurological disease at the time of hospitalization for covid-19 or influenza, the incidence of neurological disorder in the year following hospitalization was 2.8% in the covid-19 group vs. 5.0% in the influenza group.

In practice

“Although the results are different from what we expected to find, they are reassuring as we found that being hospitalized for Covid-19 did not lead to a greater need for care for common neurological disorders, compared to hospitalization for influenza,” said in a press release the Dr. Brian C. Callaghan, a researcher who participated in the study and a physician affiliated with University of Michiganin the United States.

Source

The study was led by Dr. Adam de Havenon, a doctor linked to Yale Universityin the USA, and published online on March 20, 2024 in the journal Neurology.

Limitations

The research was based on International Classification of Diseases (ICD) codes in health claims databases, which may have led to biases related to errors in classification. Furthermore, by selecting only individuals undergoing hospital care, there may have been a selection bias based on the severity of the disease.

Conflicts of interest

The study was funded by American Academy of Neurology. Dr. Adam de Havenon reported receiving consultancy fees from Integrate and from New Nordiskcopyright fees from UpToDate and have a shareholding in the TitinKM and on Certus. Dr. Brian C. Callaghan provided medical legal counsel to the DynaMed and carries out legal medical consultancy, such as those carried out for the Vaccine Injury Compensation Program. Other conflicts of interest were made available in the original article.

This content was originally published on Medscape