Influenza drug now hailed as effective

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Last year, an influential study published by the Cochrane Collaboration and the British Medical Journal cast doubt on the efficacy of oseltamivir, concluding it was little better than paracetamol at relieving symptoms. It raised tough questions for countries, including SA, that had spent money stockpiling the drug and prompted its authors to call for a revision of influenza treatment guidelines.

Now a new study, funded by oseltamivir manufacturer Roche, has found that although the drug shortened symptoms only by a day and increased the risk of nausea and vomiting, it reduced the incidence of hospitalisation by more than half when compared to a placebo, from 8.7% to 4.9%. It also cut the risk of respiratory complications requiring antibiotics from 1.7% to 0.6%.

The study found no evidence that oseltamivir caused neurological or psychological disorders, which had previously been linked to the drug.

The study was welcomed by National Institute for Communicable Diseases epidemiologist Cheryl Cohen, who said the Cochrane study had deterred some doctors from prescribing oseltamivir, branded Tamiflu by Roche.

"The study supports existing South African recommendations to provide early oseltamivir treatment to patients with confirmed or suspected influenza if they have complicated or severe disease, or fall into a group at higher risk for complications," she said.

"It is a welcome addition to the body of evidence on oseltamivir effectiveness and will hopefully lead to more evidence-based prescribing of this antiviral drug."

The Lancet study analysed individual patient data from nine published and unpublished trials comparing oseltamivir with a placebo.

The Medical Research Council's South African Cochrane Centre senior specialist scientist, Tamara Kredo, questioned the impartiality of the Lancet study.

"It's possible that this review may have been selective in inclusion or analysis of the evidence, as the funding for the study is from the same company that stands to benefit from more favourable results," Dr Kredo said.

"Based on the methods chosen by this study it's understandable that they may have views that differ from the previously published Cochrane review. The 2014 Cochrane review independently evaluated all of the Tamiflu evidence (20 trials), including previously withheld clinical trial reports from the European Medicines Agency. The Tamiflu debate at the UK parliament select committee in 2013 was informed by the Cochrane evidence.

"This was the spark for the start of the globally endorsed AllTrials campaign, which calls for all trials to be published and made accessible to ensure transparent evaluation of all evidence to inform healthcare decision-making. South Africans have the right to have access to best health evidence - selective reporting can be misleading," Dr Kredo said.

Study author Arnold Monto, of the University of Michigan School of Public Health, said: "Our meta-analysis provides compelling evidence that oseltamivir therapy reduces by one day the typical length of illness in adults infected with influenza and also prevents complications and reduces the number of people needing hospital treatment.

"Whether the magnitude of these benefits outweighs the harms of nausea and vomiting needs careful consideration."

Source: Business Day via I-Net Bridge