But one type of blood thinning pill is significantly more effective than an injection in preventing post-op blood clots in people who underwent minor orthopedic procedures, according to new research presented at the American College of Cardiology conference March 28 to 30. The discovery could make it easier for patients to care for themselves after they leave the hospital. “For convenience sake, most patients would prefer to take a pill rather than give themselves a shot,” says Elliott Antman, MD, a senior physician specializing in cardiovascular medicine at Brigham and Women’s Hospital in Boston, who was not involved with the study. A study published in the October–December 2016 issue of the journal Joints backs him up. It found that nearly 90 percent of patients who had recently undergone orthopedic surgery, which involves the bones, joints, ligaments, tendons, or muscles, preferred taking blood thinner pills over shots. This is particularly significant because people who have undergone orthopedic surgery experience a higher risk than other patients of developing a blood clot in a major vein, called deep vein thrombosis (DVT), as well as having that blood clot travel to the lungs, called a pulmonary embolism (PE), where it can cause a stroke, according to a study published in April 2018 in the journal EFORT Open Reviews. That’s because immobilization is one of the main risk factors that contribute to the formation of blood clots, according to the American Heart Association (AHA). To test whether or not a blood thinner pill called rivaroxaban could be as effective at preventing blood clots as a popular injectable blood thinner — without increasing health risks associated with the medication — French anesthesiologists designed a massive clinical trial. It spanned three years, 200 clinics, and 10 different countries, and included more than 3,600 adults who had just undergone non-major orthopedic surgery. In the study, published on March 29, 2020, in The New England Journal of Medicine, Xarelto (rivaroxaban) was actually more effective than Lovenox (enoxaparin), reducing a person’s risk of developing a blood clot by 75 percent. Patients who received an enoxaparin shot and a placebo pill were 4.5 times more likely to develop venous thromboembolism (VTE) — a combination of PE and DVT in which a blood clot develops and then blocks blood flow to the lungs — than those who were given rivaroxaban and a placebo injection. The condition was also 8 times more likely to be severe in the enoxaparin group. In addition, researchers found that waiting to give patients the drug until six to eight hours after surgery, rather than administering it right away, decreased instances of major bleeding when compared with injections, a potential risk associated with pill-form blood thinners, says Nadia Rosencher, MD, an anesthesiologist at Hôpital Cochin in Paris who coauthored the study. RELATED: One Woman’s Story of Deep Vein Thrombosis and Pulmonary Embolism
Shaping Treatment Guidelines
The pill that the team tested, rivaroxaban, also carries fewer potential side effects than warfarin, a commonly prescribed blood thinner tablet. In 2019, the American College of Cardiology, the American Heart Association, and the Heart Rhythm Society updated treatment guidelines to recommend prescribing newer blood thinners, including rivaroxaban over warfarin for atrial fibrillation, another heart condition. This new study suggested that rivaroxaban can also be used interchangeably with enoxaparin, which has been around longer, to prevent blood clots after non-major orthopedic surgery. These operations are more common than major orthopedic surgeries, which include hip and knee replacements, and which have been the focus of past research involving the drug, including a study published in 2017 in Orthopedic Research and Reviews. “You can prescribe a drug only if you have marketing authorization, which you can only get after randomized study demonstrates with enough power the drug’s efficacy without presenting a safety problem,” says Dr. Rosencher, who believes that based on the results of this study, her hospital will begin prescribing rivaroxaban over enoxaparin when appropriate, in an effort to make it easier for patients to prevent blood clots once they leave the hospital. Dr. Antman says that it’s important to understand that the focus of the study was to test the drugs’ effectiveness in prophylaxis, meaning the prevention of blood clots from forming rather than preventing existing blood clots from growing. This is an important detail, he notes, since dosages for treatment and prevention differ, and the team only tested the dose meant for prevention. Antman believes this research will be carefully considered by the organizations that determine treatment guidelines for Europe and North America.
