Analysis: Oseltamivir shortened flu duration

Oseltamivir treatment in adults with influenza shortens the time of clinical symptom alleviation by about one day, substantially reducing the risk of lower respiratory tract complications and hospitalization, according to findings from a meta-analysis of nine randomized, controlled trials involving 4,328 adult patients.

The findings of the study, which was the first to use individual patient data to evaluate the neuraminidase inhibitor, should put to rest persistent doubts about its efficacy and safety, according to the University of Michigan School of Public Health, Ann Harbor.

The safety and effectiveness of Oseltamivir has been hotly debated, with some researchers claiming there is little evidence that Oseltamivir works. “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.

The intention to treat population of 1,591 patients with confirmed influenza had a significant 21% shorter time to clinical symptom alleviation, compared with the intention to treat infected population of 1,302 patients who received placebo (97.5 hours vs. 122.7 hours, difference of 25.2 hours; time ratio, 0.79), the investigators reported.

The effects were somewhat attenuated in the 2,402 treated patients in the overall intention to treat population with a 15% reduction in time to symptom alleviation- compared with the 1,926 placebo patients in the population. But the difference remained significant (median of 17.8 hours; time. ratio, 0.85), the investigators said.

Lower respiratory track complications occurring more than 48 hours after randomization were reduced by 44% in the intention to treat infected population. Only 4.2% of Oseltamivir-treated patients required such treatment, compared with 8.7% of those who received placebo (risk ratio, 0.56). The risk of hospitalization for any cause was significantly reduced by 63% 90.6% vs. 1.7% in the groups, respectively; RR, 0.37).

The benefits of treatment came at the cost of increased risk of nausea and vomiting (RR, 1.60 and 2.43, respectively), but no effect was seen with respect to neurologic or psychiatric disorders or serious adverse events in either of the groups.

To overcome previous concerns regarding potential publication bias, the investigators included all published and unpublished sponsored randomized, placebo-controlled, doubled-blind trials of the standard prescribed Oseltamivir dose of 75 mg twice daily in adults, as well other applicable trials of the drug for the treatment of naturally occurring influenza like illness. The trials were conducted between 1997 and 2001, and included patients who were within 36 hours of feeling unwell, and who had a fever and at least one respiratory symptom and one constitutional symptom. Treatment was administered at 12-hour intervals for 5 days, and patients were followed for 21 days.