The NEJM issued an "expression of concern" Tuesday on a study it published on May 1 that suggested widely used hypertension drugs were not raising the risk of death for patients with COVID-19, as reported by ABC News.
The study relied on a database with health records from hundreds of hospitals around the world.
However, "substantive concerns" have been raised about the quality of the information, and the journal has asked the authors to provide evidence it is reliable, the editors wrote.
The same database by Surgisphere was used in an observational study of nearly 100,000 patients published in The Lancet that linked the malaria drugs hydroxychloroquine and chloroquine to a higher risk of death in hospitalized patients with SARS-CoV-2.
The Lancet issued a similar expression of concern about its study on Tuesday, saying it was aware "important scientific questions" that had been raised.
Meanwhile, a statement on Surgisphere's site says it stands behind the integrity of its studies, and notes that observational data like what it supplied from electronic health records are not a substitute for rigorous experiments to test a drug.
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