Posted by: kenwbudd | August 12, 2009

Confusion over giving antivirals to children with flu

Another pertinent study from the BMJ casts doubt over the UK’s strategy to combat H1N1 Swine Flu, is well founded.

Specifically, whether all children suspected of having H1N1 Swine flu, should be given antiviral drugs such as oseltamivir (Tamiflu) or zanamivir (Relenza).

The UK government Health Ministers, insist that everyone suspected of having H1N1 Swine flu should be offered antivirals as part of a “safety first” strategy but the BMJ study, published in their journal, suggests the strategy is misguided, at best.

Small help
It concludes that treating children under 12 with antivirals does very little, shortening the duration of disease by just a day or so, and decreasing by just 8 per cent the likelihood that an infected child will spread it to others.

Also, Tamiflu causes additional vomiting in 5 per cent of children already vomiting because of their illness. Nor does it bring any benefits for asthmatics, as implied by advice from the UK government’s Health Protection Agency.

“The results show the beneficial effect is fairly small for most children,” says Matthew Thompson of the University of Oxford, who led the research.

His team’s advice is for parents to treat mild flu symptoms with the usual medicines and the priority is in controlling the high fever, ensuring the patient gets plenty of rest and their fluid intake is maintained.

Beneficial Value unknown
Even if complications develop, the beneficial value of giving antivirals to children is unknown, the researchers say. “What we need are studies large enough to let us know if antivirals reduce the risks of serious complications such as pneumonia or hospitalisation in children,” Thompson says.

Another bonus of limiting treatment in children is that it will reduce the risk of the mutating virus developing resistance to the drugs.

UK Government’s response
Responding, the British government’s Department of Health said that the BMJ study is based on seasonal flu and so may not apply to swine flu. This is a very weak knee-jerk response with little substance.

“Whilst there is doubt about how swine flu affects children, we believe a safety-first approach of offering antivirals to everyone remains a sensible and responsible way forward,” said a spokesperson. “However, we will keep this policy under review as we learn more about the virus and its effects.”

The government can see their ass-covering strategy diminishing in the face of evidence based criticism.

Viral Influenza A
Thompson accepts that his review only looked at seasonal flu. “But about two-thirds of the studies were influenza A, which is what the current strain is,” he says. “So we would expect our results to be applicable to swine flu.”

Sharp shooting
Thompson says that other countries are deploying a more considered and targeted approach, unlike the scattergun approach in the UK. “Canada, Ireland and the US are only recommending antivirals for patients at particularly high risk, or with severe illness,” he says.

Good Advice
“It may be worth the UK Department of Health taking the new research on board and consider having a more targeted approach to the use of antivirals, or urgently conducting randomised controlled trials of children and adults to identify whether there are subgroups of children who will benefit from antivirals, and whether they do have an impact on severe complications such as pneumonia or hospitalisation,” says Thompson.

Fortunately, the decisions lie not only with the UK Government. “I hope the evidence from such trials will help parents and family doctors make sensible decisions about which children to treat.”

Results and Conclusions from BMJ Study: BMJ, DOI: 10.1136/bmj.b3172

Review methods: Eligible studies were randomised controlled trials of neuraminidase inhibitors in children aged ≤12 in the community (that is, not admitted to hospital) with confirmed or clinically suspected influenza. Primary outcome measures were time to resolution of illness and incidence of influenza in children living in households with index cases of influenza.

Results: We identified four randomised trials of treatment of influenza (two with oseltamivir, two with zanamivir) involving 1766 children (1243 with confirmed influenza, of whom 55-69% had influenza A), and three randomised trials for postexposure prophylaxis (one with oseltamivir, two with zanamivir) involving 863 children; none of these trials tested efficacy with the current pandemic strain. Treatment trials showed reductions in median time to resolution of symptoms or return to normal activities, or both, of 0.5-1.5 days, which were significant in only two trials. A 10 day course of postexposure prophylaxis with zanamivir or oseltamivir resulted in an 8% (95% confidence interval 5% to 12%) decrease in the incidence of symptomatic influenza. Based on only one trial, oseltamivir did not reduce asthma exacerbations or improve peak flow in children with asthma. Treatment was not associated with reduction in overall use of antibiotics (risk difference –0.30, –0.13 to 0.01). Zanamivir was well tolerated, but oseltamivir was associated with an increased risk of vomiting (0.05, 0.02 to 0.09, number needed to harm=20).

Conclusions: Neuraminidase inhibitors provide a small benefit by shortening the duration of illness in children with seasonal influenza and reducing household transmission. They have little effect on asthma exacerbations or the use of antibiotics. Their effects on the incidence of serious complications, and on the current A/H1N1 influenza strain remain to be determined.

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