Hospitalized children with influenza A H1N1 (2009) infection: a Spanish multicenter study.

Objectives: Even though the majority of cases of influenza A H1N1 (2009) in children are mild, severe complications have been reported. Our objective was to describe the Influenza A H1N1 (2009) complications in pediatric population in Spain.

Methods: This was a multicenter descriptive study including patients younger than 14 years attending 15 emergency departments and hospitalized with laboratory-confirmed influenza A H1N1 (2009) infection from August to December 2009. Patients who did not meet any of the admission criteria recommended by the Health Spanish Authorities were excluded. A standardized report form was used to collect information on demographics, risk factors, clinical and microbiological data, treatment, and outcome. Potential risk factors associated with intensive care requirement (assisted ventilation and/or inotropic support) were analyzed.

Results: Three hundred eight patients were included. The hospitalization rate was 20.5 per 100,000 children younger than 14 years. Median age was 48 months; 21% had underlying medical conditions. The most common diagnosis at admission was presumed bacterial pneumonia (42.5%). Oseltamivir was prescribed on admission to 207 children (67.2%) and antibiotics to 199 (64.6%). Bacterial coinfection was confirmed in 29 patients (9.4%). Fifty-four patients (17.5%) were admitted to an intensive care unit, and 6 (1.9%) died. Logistic regression model revealed that confirmed bacterial coinfection was associated with intensive care requirement (odds ratio, 3.3; 95% confidence interval, 1.1-10.0).

Conclusions: Respiratory manifestations were the main complication described. Although the majority of patients had a favorable evolution, a remarkable morbidity and mortality were observed. Patients with confirmed bacterial coinfection were at high risk of severe illness.