The MARINER Trial: Know The Risk of Blood Clots in the Hospital

Updated October 2019

Did you know that in the United States alone, 400,000 blood clot events occur in patients recently discharged from the hospital? And that blood clots are the most common cause of preventable hospital deaths?

The MARINER trial looked at this issue and the results were released in August 2018 at the European Society of Cardiology Congress.

MARINER was a randomized, double-blind study that examined the safety and efficacy of rivaroxaban in preventing venous thromboembolism (VTE or blood clot) events and VTE-related deaths in medically ill patients after they were discharged from the hospital.

“The trial’s aim was to optimize blood clot prevention in medically ill patients with the specific aim of reducing VTE,” explained Dr. Ebrahim Barkoudah, Associate Director of Hospital Medicine Unit at Brigham and Women’s Hospital.

In the trial, 12,024 medically ill patients were randomized to receive 10 mg of rivaroxaban once daily for 45 days or a placebo for 45 days. The primary efficacy outcome was symptomatic VTE or VTE-related death, and the principal safety outcome was major bleeding.

Among the patients in the trial, 50 of the 6,007 patients on rivaroxaban and 66 of the 6,012 patients on the placebo experienced symptomatic VTE or VTE-related death. Twelve of the 5,982 patients on rivaroxaban and 9 of the 5,980 patients in the placebo group experienced major bleeding.

The trial results were considered neutral. “Rivaroxaban was not associated with a significantly lower risk of symptomatic VTE and VTE-related death than placebo. However, it did reduce symptomatic VTE. The incidence of major bleeding was low,” study investigators concluded. 

Secondary endpoints demonstrated that certain groups of patients—those with heart failure, for instance—might benefit more from extended VTE thromboprophylaxis, but additional studies will be needed to confirm these results.

Recognizing Risk

Although MARINER was a neutral trial, it does emphasize the risk that patients face while in the hospital and after discharge.

“This trial added to our knowledge and sheds light on how we look at the risk,” explained Dr. Barkoudah. “Hospitalists, in particular, don’t see the risk in their patient communities because they’re discharging the patient, but the risk is out there. The patient leaves with the risk.”

“We can do a better job to make sure that VTE is prevented,” Dr. Barkoudah stressed. 

Part of the risk comes from patients being immobile in the hospital and then after discharge, when they are no longer being motivated to move by a treatment team. By raising awareness around this issue, patients can be empowered to make sure they are getting the care they need to avoid a blood clot.

What can patients do?

“The risk for each patient is individual. I would encourage every patient to start a discussion with their healthcare providers,” said Dr. Barkoudah. “The ultimate cure is for everyone to move. Please, if you can get out of bed safely, with the help of physical therapy or the treatment team, do it and do it as soon as possible.”

If you have a history of blood clots, it’s important that your healthcare team knows about it. You should also let them know about any medications you’re taking, including anticoagulants. 

Being in the hospital is a scary and stressful time, but communicating your medical history to providers and knowing the right questions to ask can make all the difference.

Update: In October 2019, the U.S. Food and Drug Administration approved rivaroxaban for the prevention of VTE (blood clots) in hospitalized medically ill patients at risk for thromboembolic complications who do not have a high risk of bleeding. Rivaroxaban can be prescribed during hospitalization and continued for 31-39 days after discharge.

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