Results of a study undergone by German scientists revealed that stroke patients given Amgen and Johnson & Johnson’s anemia drug Eprex might increase their risk for death, the US Food and Drug Administration warned on Friday.

Eprex belongs to a class called erythropoiesis-stimulating agents, or ESAs, which were approved for patients with kidney disease and cancer. The German study’s main goal was to see whether Eprex could improve brain functions in stroke patients. This use of the drug has not been yet approved in the US.

The study found that 16 percent of the 522 patients involved died within 3 months, compared with 9 percent of those given a placebo. Considering the study findings, the FDA decided to monitor patients enrolled in other ongoing trials for adverse outcomes and evaluate whether the potential benefits for enrolled patients outweigh the risks in these trials.

Johnson & Johnson last week alerted the FDA about the study findings, spokesman Mark Wolfe said, adding that the company was doing addition analyses to better understand the findings.

The FDA expects to receive more data on the study “within the next several weeks.” Also, when the agency’s analysis is complete it will “communicate our conclusions and recommendations to the public.”

Eprex is known generically as epoetin alfa. Johnson & Johnson also sells epoetin alfa under the name Procrit. Amgen Inc sells a version under the name Epogen. Amgen’s spokeswoman Emma Hurley said the company is not supporting or sponsoring any studies of ESAs for brain protection and has not found evidence of widespread use for that purpose.