Background: 600,000 deaths world-wide are estimated to be directly or indirectly attributable to respiratory syncytial virus (RSV).
Objectives: To determine: 1) the mortality rate; 2) risk factors for death in children with severe RSV infection.
Setting: 20-bed regional multidisciplinary tertiary pediatric intensive care unit (PICU) in a university-affiliated children’s hospital.
Methods: Cohort study of all children with severe RSV infection covering 8 consecutive RSV seasons (1999 – 2007), using PICU admission as a marker of severity.
Results: Of the 406 RSV-positive patients that were admitted to PICU: 98.5% required mechanical ventilation; 35 children died – median age 5.1 months (IQR: 2.4 – 13.6), length of PICU stay 16 days (IQR: 8 – 31) and 371 survived - median age 2.5 months (IQR: 1.2 – 9), length of PICU stay 5 days (IQR: 4 – 9). The overall PICU RSV mortality was 8.6% with a standardised mortality ratio of 0.76. During the study period 2009 RSV-positive patients were admitted to the children’s hospital, giving hospital RSV mortality rate of 1.7%.
Of the deaths 18 were directly RSV-related (RSV bronchiolitis-related mortality PICU 4.4% and hospital 0.9%) as the patients were still RSV positive when they died and 17 children died from non-pneumonitis causes after becoming RSV negative.
All of the RSV deaths had pre-existing medical conditions – chromosomal abnormalities 29%, cardiac lesions 27%, neuromuscular 15%, chronic lung disease 12%, large airway abnormality 9%, immunodeficiency 9%. Nineteen children (56%) had pre-existing disease in two or more organ systems (relative risk/RR 4.38).
Predisposing risk factors for death were pre-existing disease (RR 2.36), cardiac anomaly (RR 2.98) and nosocomial / hospital-acquired RSV infection (RR 2.89). There is an interaction effect between pre-existing disease, nosocomial / hospital-acquired RSV infection and mortality (p < 0.001).
Conclusions: Pre-existing disease / co-morbidity, in particular multiple pre-existing diseases and cardiac anomaly, is associated with a significantly higher risk of death from severe RSV infection. Nosocomial / hospital-acquired RSV infection is an additional major risk factor for death in children with severe RSV infection.