Critical influenza virus infection

Objective: To determine the risk of death from influenza infection in child ren with chronic underlying disease. Methodology: An 18-year retrospective study of children with 'critical' inf luenza A or B virus infection, defined as requiring admission to intensive care or resulting in death, but excluding laryngotracheobronchitis (LTB). I nfluenza infection was diagnosed by viral culture and/or immunofluorescence of respiratory secretions. Patients with LTB were analysed separately. Results: There were 27 cases of critical influenza virus infection over the study period, comprising 26 admissions to the intensive care unit (excludi ng LTB) and one death on the general wards. Thirteen (48%) of the 27 childr en had chronic underlying disease. In addition, 12 children with LTB were a dmitted to the intensive care unit. The LTB children were older and less li kely to have chronic underlying disease. Nosocomial infection caused seven (26%) of the 27 critical infections. Nine (33%) of the 27 children with cri tical influenza died. Six (46%) of 13 children with chronic underlying dise ase and influenza admitted to intensive care died, compared with three of 1 4 (21%) without any underlying disease (odds ratio = 3.1, 95% confidence in terval 0.6-14.0). Conclusions: Critical life-threatening influenza virus infection was uncomm on, but the mortality was high (33%), particularly in children with chronic underlying disease. Nosocomial infection with influenza was an important c ause of admission to intensive care.