Pandemic H1N1 influenza-associated hospitalizations in children in Madrid, Spain

Area of Science:

• Pediatric Infectious Diseases
• Epidemiology of Viral Illnesses
• Public Health Surveillance

Background:

• The 2009 pandemic influenza (pH1N1) posed a significant threat to global health.
• Understanding the specific impact on pediatric populations is crucial for effective public health strategies.
• Children with pre-existing health conditions may be at higher risk for severe outcomes.

Purpose of the Study:

• To characterize the epidemiological and clinical features of pediatric patients hospitalized with pH1N1.
• To identify risk factors associated with severe pH1N1 disease and pediatric intensive care unit (PICU) admission in children.
• To compare outcomes between children with and without underlying medical conditions.

Main Methods:

• Retrospective chart review of 517 children under 14 years old diagnosed with pH1N1 via PCR in Madrid, Spain (May-November 2009).
• Data analysis compared outcomes based on age, presence of high-risk medical conditions, and PICU admission.
• Statistical analysis included odds ratios (OR) and confidence intervals (CI) to assess risk factors.

Main Results:

• 142 patients (27.5%) had underlying illnesses, most commonly immunosuppression and asthma.
• Children with underlying conditions experienced longer hospital stays and higher rates of intensive care and mechanical ventilation.
• PICU admission was associated with abnormal chest X-ray (OR 3.5), neurological conditions (OR 3.1), and immunosuppression (OR 2.9).
• Five patients (0.9%) died, primarily those with severe neurological disease or cancer.

Conclusions:

• Underlying medical conditions significantly increase the severity of pH1N1 disease in children.
• Abnormal initial chest X-ray, underlying neurological conditions, and immunosuppression are key risk factors for PICU admission.
• Targeted monitoring and interventions for high-risk pediatric populations are essential during influenza pandemics.