The Food and Drug Administration announced on Friday that they are reviewing a higher rate of deaths among patients given Johnson & Johnson anemia drug Eprex in a German study involving stroke patients. The study was testing if the drug could improve brain function in stroke patients.

Eprex is known generically as epoetin alfa. The company also sells epoetin alfa under the name Procrit, Amgen sells a version under the name Epogen. The drugs belong to a class called erythropoiesis-stimulating agents, or ESAs, which were approved for treating patients with kidney disease and cancer.

The German study involved 522 patients who were given relatively high doses of Eprex for three days or a placebo. It found that 16 percent of patients getting the drug to protect the brain died within three months, compared with 9 percent of those on a placebo. The drug is not approved in the US for treating stroke patients and most of those involved in the study weren’t anemic.

The German study” suggests the need to closely monitor patients enrolled in other ongoing trials for adverse outcomes and to evaluate whether the potential benefits for enrolled patients outweigh the risks in these trials,” the FDA said.

Johnson & Johnson informed the FDA last week about the findings of the German study, which started in 2003 and was designed by independent investigators in Europe.

ESAs’ safety came under scrutiny in recent years after a series of studies revealed that patients treated with them were developing tumors or had shorter survival rates. In July, the FDA ordered strong new warnings on the medicines.

More data on the drug are expected in the following months, the FDA said. The agency is expected to announce its conclusions when the review is complete.