Pre-existing disease is associated with a significantly higher risk of death in severe respiratory syncytial virus infection.
BACKGROUND
600,000 deaths worldwide are estimated to be directly or indirectly attributable to respiratory syncytial virus (RSV).


OBJECTIVE
To determine: (1) the mortality rate; and (2) risk factors for death in children with severe RSV infection.


METHODS
20-bed, regional, multidisciplinary, tertiary, paediatric intensive care unit (PICU) in a university-affiliated children's hospital.


METHODS
Cohort study of all children with severe RSV infection covering eight 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 (interquartile range (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 a 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%, and 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/comorbidity, 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.
Thorburn
K
K
Department of Paediatric Intensive Care, Royal Liverpool Children's Hospital, Liverpool L12 2AP, UK. kent.thorburn@alderhey.nhs.uk
D002869:Chromosome Aberrations; D003428:Cross Infection / Q000401:mortality; D004739:England / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D006330:Heart Defects, Congenital / Q000401:mortality; D006776:Hospitals, Pediatric; D006801:Humans; D007223:Infant; D015278:Intensive Care Units, Pediatric; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D012121:Respiration, Artificial; D018357:Respiratory Syncytial Virus Infections / Q000401:mortality* / Q000628:therapy / Q000635:transmission