Severity Similar in Pediatric Patients with Influenza A or B

New research shows mortality rates for hospitalized pediatric patients did not differ whether it was due to Influenza A or Influenza B.

A team, led by Pinar Vazici Ozkaya, MD, Ege University, Pediatrics Intensive Care, identified the clinical features and mortality linked to severe Influenza A and B virus infections for pediatric patients admitted to the pediatric intensive care unit (PICU).

While rare, deaths from influenza have been reported in children, even without risk factors.

Examining the Data

In the retrospective study, the investigators examined children with confirmed influenza infection admitted to the PICU between 2012-2019. The team collected demographic features, risk factors, clinical data, microbiological data, complications, and outcomes. The data also included the timing of admission, length of PICU stay, microbiology results, pediatric index of mortality 2 score (PIM2), and mortality.

High resolution computed tomography (HRCT) was also performed in 7 patients.

Overall, there were 713 pediatric patients diagnosed with laboratory-confirmed influenza during 7 influenza seasons between 2012-2019 related to lower respiratory tract infections. Approximately 6% (n = 46) of patients were admitted to the PICU and 67.4% (n = 31) were diagnosed with Influenza A, compared to 15 patients diagnosed with Influenza B.

The investigators evaluated medical records of the influenza-positive patients and examined accompanying bacterial and other viral infections at the time of admission.

Patient Demographics

A total of 27 (58.7%) patients had an underlying medical condition, including prematurity (19.5%), hemato-oncological disease (10.9%), and chronic lung disease (8.7%).

The most common symptoms were fever (n = 42; 91.3%), and cough (n = 36; 78.3% and pulmonary rales (n = 39; 84.8%) and tachypnea (n = 36; 78.3%) were the most common physical examination findings at admission.

The most common abnormal laboratory findings were lymphopenia (58.7%), high lactate dehydrogenase (LDH) (54.3%), and high aspartate transaminase (AST) levels (56.5%).

The mean length of PICU stay was 17.6 ± 24.3 days and every patients needed ventilatory support, but 73.9% (n = 34) of patients required invasive mechanical ventilation support. In addition, 15.2% (n = 7) of patients required bilevel positive airway pressure (BIPAP) and 13% (n = 6) of patients required high-flow oxygen support.

The mean length of stay for patients on the invasive mechanical ventilatory was 14.8 ± 24.8 days and the overall mortality rate for patients admitted to PICU was 17.3% (n = 8).

The epidemiologic and clinical characteristics were similar for both patient groups, but the lactate dehydrogenase levels were significantly higher in the pediatric patients with Influenza A.

“Although the influenza A to B ratio among the patients admitted to the PICU was 2.06, the percentage of cases requiring PICU admission were nearly two times higher in Influenza B cases,” the authors wrote. “There was no statistically significant difference in disease severity and complications in patients with Influenza A and Influenza B.”

Influenza is responsible for an average of 200,000 hospitalizations and 36,000 deaths annually in the US.

The study, “Severe Influenza Virus Infection in Children Admitted to the PICU: Comparison of Influenza A and Influenza B Virus Infection,” was published online in Current Protocols.