Johnson & Johnson’s Natrecor heart failure treatment may be linked to a greater risk of death when compared with standard therapy, a review of data in a prominent medical journal said on Tuesday.

Among studies of nearly 900 heart failure patients, 7.2 percent of patients died within 30 days of treatment with Natrecor, known generically as nesiritide, compared with a 4 percent death rate among a control group.

“In conclusion, nesiritide may be associated with an increased risk of death within the first month after its use,” the authors wrote in the Journal of the American Medical Association.

“The possibility of an increased risk of death should be investigated” in a large controlled trial, they added.

Heart failure is a chronic condition in which the heart loses its ability to pump blood effectively.

Johnson and Johnson spokesman Mark Wolfe said its own data shows no statistical difference in mortality, though the company is conducting its own safety review.

Wolfe said the studies in question were not designed to look at mortality and that patients had other fatal medical conditions, which could skew results.

Lead study author Jonathan Sackner-Bernstein, a doctor at North Shore University Hospital in New York, said that data is the best available and called Johnson and Johnson irresponsible for sitting on signals of safety problems.

“This is a drug with a modest clinical benefit in a high risk situation, where the best data that exists suggests strongly that doctors should be concerned” about these trends, he told Reuters.

The drug is typically given when a heart failure patient winds up in the hospital after an acute attack.

Last month, an article in the journal Circulation by some of the same investigators found that the drug worsened kidney function by as much as 50 percent, based on a review of 1,200 patients. Reduced kidney function is a well-known side effect of Natrecor and it is listed on the label.

In the current article, investigators pooled data from three studies and analyzed the mortality effect, not the gold standard of a prospectively controlled trial, the authors said.

“Our findings should be viewed as hypothesis generating rather than as conclusive evidence of harm,” the paper said.

Still, safety of currently marketed prescription drugs is under a spotlight as two drugs, Merck & Co Inc.‘s Vioxx and Pfizer Inc.‘s Bextra were pulled from the market in recent months.

Signals about safety of these drugs were seen in the literature before more serious concerns came to light.

“The sequence of events leading to the withdrawal of (Vioxx) from the market underscores the importance of rigorous evaluation of safety from all data sources,” the review authors said.