Neurologic complications associated with influenza in hospitalized children

Issue: June 2013

WASHINGTON — Neurologic complications of influenza led to increased morbidity and mortality in hospitalized children, according to study results presented at the Pediatric Academic Societies Annual Meeting.

“Influenza-related neurologic complications coincide with both seasonal and pandemic flu and have been reported worldwide among all ages,” Michelle R. Torok, PhD, of the University of Colorado said at the meeting. “Previous studies have shown that children with an underlying neurologic or neuromuscular disease are at increased risk for severe outcomes for influenza.”

The retrospective cohort study included 10,576 pediatric inpatients from 17 hospitals nationwide that received an influenza diagnosis during the October to May flu seasons from May 2003 through December 2011. According to researchers approximately half of the participants were male, two-thirds were aged less than 3 years, and 60% have public insurance.

Researchers found that 35% of patients had at least one complex chronic condition, 22% stayed in the ICU and 1% resulted in death.

According to researchers 5% of discharged included the following non-seizure influenza-related neurologic complications: encephalopathy/encephalitis or myelitis (40%), meningitis (6%), stroke (13%) and post-infectious encephalitis (1%). Researchers also found that discharges with influenza-related neurologic complications were more likely to have any complex chronic condition (OR=2.6, 95% CI: 2.1-3.1) compared to those with no complex chronic condition, as were those with any neurologic/neuromuscular complex chronic condition (OR=9.3, 95% CI: 6.8-12.7).

Researchers found that the smallest proportion of non-seizure influenza-related neurologic complications was diagnosed among the infant age group. Children with any complex chronic condition and those with an underlying neurologic condition were also more likely to be diagnosed with influenza-related neurologic complications.

“ICU stay and death were also more prevalent in children with neurologic complications of flu,” Torok said. “Kids with an influenza-related neurologic complication were more likely to be hospitalized for at least three days compared to children without influenza-related neurologic complications.”

According to researchers influenza-related neurologic complications are not common in general but seem to be more common in children with underlying neurologic and neuromuscular diseases. Twenty percent of those children were diagnosed with an influenza-related neurologic complication compared to 3% of children with a non-neurologic complex chronic condition.

“These findings underscore the importance of monitoring neurologic function in children with underlying neurologic or neuromuscular disease with suspected or confirmed influenza,” researchers wrote in the abstract. “Prospective studies will help to clarify the role of influenza-related neurologic complications in increasing severity, length of stay, and to determine whether influenza-related neurologic complications results in long term disability for affected children.”

For more information:

Torok MR. Abstract #3150.8. Presented at: Pediatric Academic Societies Annual Meeting; May 4-7, 2013; Washington DC.

Disclosure: The researchers report no relevant financial disclosures.