Convalescent plasma transfusions may not be effective in Ebola

1. Patients with Ebola virus disease (EVD) who received convalescent plasma transfusions had a 7% less risk of mortality than controls that did not receive convalescent plasma.

2. In this trial, the risk difference of 7% was not sufficient to deem convalescent plasma transfusions as a clinically important treatment option.

Evidence Rating Level: 2 (Good)

Study Rundown: EVD has a high case fatality rate of approximately 40%-60%. The high risk for mortality highlights the need for effective EVD treatments. There has been previous evidence that transfusion plasma from donors in the convalescent phase of EVD recovery may decrease the risk of death in patients actively infected. However, this is only useful if this treatment is efficacious. This comparative study aimed to evaluate the safety and efficacy of convalescent plasma for the treatment of EVD in Guinea.

The risk of death in the convalescent plasma group was 31% and the risk of death in the control group was 38%. The risk difference was -7% in favor of the convalescent plasma group. This risk difference did not meet the predetermined 20% risk difference cut off for clinical importance. No serious adverse reactions were associated with convalescent plasma use. Strengths of this study include inclusion of all patients regardless of age or sex. No measurement of the neutralizing antibody titers in donor plasma prior to transfusion was collected. This information could have helped to interpret the efficacy of transfusions.

Click to read the study, published today in NEJM

Relevant Reading: Clinical presentation of patients with Ebola virus disease in Conakry, Guinea

In-Depth [comparative study]: This nonrandomized, comparative study was conducted at the Ebola Treatment Unit in Guinea from February 2015 to August 2015. All patients, of any age and including pregnant women, with symptomatic laboratory-confirmed EVD were enrolled and received a total of 500 mL of ABO-compatible convalescent plasma from a donor who recovered from EVD. Convalescent plasma antibody levels were not measured prior to transfusion. The control group consisted of patients who had been admitted to the Ebola Treatment Unit during the preparatory phase of the study, where the convalescent plasma was not available. Real-time PCR was used to determine Ebola viral load. The primary outcome was the risk of death 3-14 days after convalescent plasma administration. The difference in risk of death would be deemed clinically important if there was a 20% decrease in patients receiving convalescent plasma.

A total of 84 patients were treated with plasma and were also included in the final analysis. The analysis revealed a risk difference of 7% between the two groups; 31% for the convalescent-plasma group and 38% in the control group (95% [CI], -18 to 4). After adjustment for age and baseline viral load, the risk difference decreased to 4%. There seemed to be no adverse reactions connected to the use of convalescent plasma.

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