According to a long-term study, Uloric for gout may cause patients with prior existing heart conditions to face an increased risk of death.

Reuters Health reports that the study discovered that Uloric causes almost a 34 percent increased risk of death for patients with prior cardiovascular disease than with an older gout medicine, allopurinol. In considering deaths from any other causes, researchers found that Uloric possessed a 22 percent higher risk.

Dr. William White of the University of Connecticut School of Medicine told Reuters Health, “The results are entirely unexpected and we don’t have a mechanistic explanation for them.”

The study, known as the CARES study, was presented at an annual meeting at the American College of Cardiology in Orlando. Though the study found that participants taking Uloric faced an increased risk of heart complications, researchers also concluded that the rates of non-fatal heart attack, rhythm problems and hospitalization for heart failure, major cardiovascular events, were similar among the two gout medications.

Almost 6,190 volunteers participated in the CARES study. All participants possessed histories for stroke, heart attack, major cardiovascular disease, transient ischemic attack, and hospitalization for unstable angina. Half of the participants remained in the study for at least 32 months.

Participants, as part of the CARES trial, were randomly assigned one of the two gout medications, Uloric or allopurinol. Within a time-frame of 2.5 and 6.5 years, the medical health outcomes of the participants were tracked.

Most of the patients, however, failed to continue the study on either medication. Almost 57.3 percent failed to stay on Uloric, while 55.9 percent failed to continue their use of allopurinol. The rate of gout flares with participants taking Uloric was 0.68 per patient per year, while the rate with allopurinol was 0.63 per patient per year.

The Uloric for gout study was published by the New England Journal of Medicine online in March of 2018.

Reuters Health reported on the study and Dr. White told reporters that almost 92.5 percent of patients, the majority of people, are treated with allopurinol, while another 7.5 percent take Uloric. Uloric is also almost 45 times more expensive than allopurinol, according to prices on goodrx.com.

According to White, who is also a professor of medicine at UConn’s Calhoun Cardiology Center in Farmington, “It is probable that physicians will be concerned about the results of this study and that could affect their prescribing habits in patients with cardiovascular disease and gout.”

When the Uloric was first approved by the U.S. Food and Drug Administration (FDA) in 2009, the CARES study was mandated by the FDA to be performed by Uloric’s makers, Takeda Pharmaceuticals. Prior to the study, there was evidence of Uloric causing non-fatal cardiovascular problems.

Allopurinol has been on the market since 1966. However, the drug does carry side effects that can include kidney issues, particularly among African-Americans.

There are already elevated risks of potential side effects with people that have gout. Risks may include chronic kidney and cardiovascular disease.

Another study will evaluate patients taking allopurinol or Uloric without histories of cardiovascular disease.

According White, the study is called the FAST trial, which will be “evaluating febuxostat versus allopurinol in gout patients without this high level of cardiovascular disease… This study will define cardiovascular safety of these drugs in lower risk patients.”