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ARREST trial finds adding rifampicin does not improve outcomes from blood infections

25 April 2017

The results of the ARREST trial, which looked at how to improve outcomes for patients with Staphylococcus aureus blood infections, were presented on 20 April at the 27th European Congress of Clinical Microbiology and Infectious Diseases in Vienna, Austria.

ARREST tested whether adding an antibiotic drug called rifampicin (or rifampin) to standard antibiotic treatment for Staphylococcus aureus blood infections, would reduce:

  • deaths
  • the infection not being cured
  • the infection coming back.

Staphylococcus aureus is a common type of bacteria, and is often not severe. However, if it infects a person's blood, it can be life-threatening. People who have a weakened immune system (for example from cancer chemotherapy), or who use medical equipment that goes directly into their body, are vulnerable to Staphylococcus aureus blood infections.

The ARREST trial took place between December 2012 and January 2017. People who agreed to take part in the trial were randomly split into 2 groups.

  • 388 people received standard antibiotic treatment for as long as they needed plus an extra placebo (dummy) treatment for 2 weeks.
  • 370 people received standard antibiotics for as long as they needed plus additional rifampicin for 2 weeks.

The trial followed up how people were doing for 12 weeks. Many of the people taking part in ARREST had other illnesses as well. These included heart failure, lung disease, cancer, moderate or severe renal (kidney) disease, and diabetes.

The ARREST trial found that people who had rifampicin in addition to standard antibiotic treatment did no better than people who had just standard antibiotic treatment. The overall proportion of people who:

  • died within 12 weeks of starting the trial,
  • or whose infection did not get better within 2 weeks,
  • or whose infection came back again,

was very similar in the two groups (18% in the rifampicin group versus 19% in the placebo group). This difference is not big enough for us to be confident that adding rifampicin improves standard antibiotic treatment.

When the researchers looked at each of these aspects separately, they found rifampicin made no difference to the numbers of deaths, nor did it reduce the number of patients who did not get better within 2 weeks. There was some evidence that rifampicin may reduce the number of infections that came back again. But this improvement was not big enough to make a difference to the overall outcome of the trial.

People in the group who had rifampicin were no more likely to have a serious or severe side-effect than those in the group who had placebo, although rifampicin did cause some less severe side-effects which did complicate people's treatment.

These results means that standard treatment is likely to stay the same until future trials find other ways to improve treatment. It is disappointing that rifampicin does not improve overall treatment outcomes for people with Staphylococcus aureus blood infections. But the ARREST trial results mean doctors can now be confident that they do not need to give rifampicin to patients with Staphylococcus aureus blood infections.

The ARREST trial was carried out in 29 hospitals in England. It was sponsored by the Medical Research Council, and funded by the Health Technology Assessment Programme of the National Institutes of Health Research.