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H1N1 Death Rate Higher in Kids With MRSA
Children critically ill with the pandemic H1N1 flu were at increased risk of death if they had a pre-existing neurologic condition or immune suppression, researchers reported.
But among previously healthy children admitted to intensive care with the pandemic flu, the only significant risk factor for death was a bacterial co-infection with Staphylococcus aureus, according to Adrienne Randolph, MD, of Children's Hospital Boston, and colleagues.
Overall, in a cohort of 838 patients admitted to 35 pediatric ICUs across the U.S., 75 died, almost half because of inability to ventilate and a quarter because of multi-organ failure, Randolph and colleagues reported online in Pediatrics.
Most of the patients- 70%-- had at least one pre-existing condition, as previous research has suggested, and more than three-quarters of the deaths were among children with such conditions, the researchers reported.
The findings come from an analysis of confirmed or probable pandemic flu cases from patients ages 20 or younger admitted to intensive care from April 15, 2009, to April 15, 2010 at hospitals taking part in the Pediatric Acute Lung Injury and Sepsis Investigators network.
The median age of patients was 6, 58% were boys, and 88.2% were treated with oseltamivir (Tamiflu), including 5.8% who were started on the drug before ICU admission.
The researchers also found:
Most patients had respiratory failure -- 564 (67.3%) were placed on mechanical ventilation and 162 (19.3%) were given vasopressors
Of the 75 who died, 18 (24%) had been previously healthy
71 (8.5%) had a presumed diagnosis of S. aureus co-infection of the lung within 72 hours after ICU admission, and 48% were methicillin-resistant (MRSA)
In a multivariate analysis, preexisting neurologic conditions or immunosuppression, encephalitis, myocarditis, early presumed MRSA lung co-infection, and female sex were mortality risk factors.
Specifically, the relative risks of death were:
1.9 (95% CI 1.2 to 3.0, for girls, P=0.003)
1.9 (95% CI 1.1 to 2.7, for those with a pre-existing neurologic condition, P=0.01)
2.2 (95% CI 1.1 to 4.5, for immune compromise, P=0.02)
3.4 (95% CI 1.6 to 7.5, if encephalitis was diagnosed, 14 cases, P=0.002)
3.8 (95% CI 1.2 to 12.0, if myocarditis was diagnosed, 6 cases, P=0.03)
3.3 (95% CI 1.7 to 6.4, for presumed MRSA co-infection within 72 hours of admission, P=0.0005)
Strikingly, among the 251 previously healthy children, only early presumed MRSA co-infection of the lung was a risk factor for death, with a relative risk of 8.0 and a 95% confidence interval from 3.1 to 20.6, which was significant at P<0.0001.
Most of the children admitted to the study ICUs who had MRSA co-infection and died had been treated at or before ICU admission with vancomycin (Vancocin), Randolph and colleagues reported.
That implies, they argued, that children urgently need, "prevention and control strategies for increasing influenza-related immunity and optimizing antiviral treatment of influenza, new therapies for treating severe influenza, and new treatment strategies for MRSA pneumonia complicating influenza."
The researchers cautioned that pandemic flu was confirmed in only 65% of the cases. The remaining 35% had confirmed influenza A without further subtyping and were regarded as probable cases, since that was the predominant strain in the U.S. during the study period of pandemic H1N1.