Clinical Question

Does oseltamivir reduce the likelihood of hospitalization in adults with influenza?

Bottom Line

There is no evidence that oseltamivir reduces the likelihood of hospitalizations in adults with influenza, even in high-risk or older patients; however, it has relatively common and nonserious harms. (Level of Evidence = 1a)

Synopsis

In 2012, a meta-analysis reported on published and unpublished studies of oseltamivir. It was less effective than what was reported in the published trials in terms of mean reduction of symptom duration (only 21 hours), it did not reduce the likelihood of complications once acute bronchitis was excluded as a complication, and there was no difference in the likelihood of complications (1.3% for oseltamivir vs. 1.2% for placebo). In 2014, these findings were largely confirmed by a similar meta-analysis; however, two industry-sponsored analyses found a reduction in hospitalizations with oseltamivir. This study is an updated meta-analysis of randomized trials that compared oseltamivir with placebo for the outcome of hospitalization. The authors identified 15 randomized trials (including six studies that have been published since 2014) with a total of 6,166 participants confirmed to have influenza and randomized to receive oseltamivir or placebo. The patients' mean age was 45.3 years, and 54% were female. The studies were performed in outpatient or primary care settings. Patients who received oseltamivir were not less likely to be hospitalized (relative risk [RR] = 0.79; 95% CI, 0.48 to 1.29; risk difference = −0.17%; 95% CI, −0.23% to 0.48%), and this finding had good homogeneity (I² = 0%). Oseltamivir did not reduce hospitalizations in older patients (RR = 1.01; 95% CI, 0.21 to 4.90) or high-risk patients (RR = 0.65; 95% CI, 0.33 to 1.28). The authors also analyzed harms and found increases in nausea (number needed to harm = 9) and vomiting (number needed to harm = 6), with no effect on cardiovascular, neurologic, or psychiatric events.