Sea Change Needed for VTE Prevention

A new observational study shows that venous thromboembolism (VTE) in hospitalized patients and in outpatients is inextricably linked, and that efforts are needed to improve prevention of VTE. Dr Frederick A Spencer (McMaster University, Hamilton, ON) and his team report their findings in the July 23, 2007 issue of Archives of Internal Medicine.

In an accompanying editorial, Dr Samuel Z Goldhaber (Brigham and Women's Hospital, Boston, MA) says the paper by Spencer et al is a "landmark article... of major importance." Another study, ENDORSE, reported recently at an international meeting, has shown that the low rate of prophylaxis for VTE is a worldwide problem that needs to be addressed.

He believes that physicians should shoulder much of the blame: "We doctors tend to concentrate on the illness for which our patient is hospitalized. Preventing pulmonary embolism is often not on our radar screen." However, he is optimistic that things are beginning to change: "I predict that preventing outpatient VTE will be the 'hot button' issue in 2008."

Another study in the same issue, a meta-analysis by Ms Lironne Wein (Monash University, Melbourne, Australia) and colleagues, helps to quantify the reduction in risk associated with different pharmacologic agents for preventing VTE among hospitalized patients.

"Landmark" Article on Outpatient VTE

In their study, Spencer et al analyzed the medical records of residents from the Worcester, Massachusetts metropolitan area who were diagnosed with VTE during 1999, 2001, and 2003.

A total of 1897 subjects had a confirmed episode of VTE. In all, 1399 (73.7%) of these patients developed VTE in the outpatient setting, and a substantial proportion of these (n = 516) had been hospitalized in the preceding 3 months - half for medical reasons and half to undergo surgery. Among these 516 patients, fewer than half (42.8%) received anticoagulant prophylaxis for VTE during that hospital visit. And 67% of these 516 patients had VTE within one month of their hospitalization.

"Because most of the cases of VTE occurred within 29 days of hospital discharge (and 41% occurred within 14 days), it is not unreasonable to assume that some of these cases could have been prevented simply by increased use of appropriate in-hospital deep vein thrombosis (DVT) prophylaxis (eg, compression stockings, pneumatic compression devices, and, in high-risk patients, anticoagulants)," the authors write.

In addition, around half of the outpatients who experienced VTE after hospitalization had a length of stay that was four days or less. This suggests that patients in the hospital for only a short time should also be given preventive therapy, and that some might benefit from anticoagulant therapy even after discharge, they say.

In his editorial, Goldhaber says: "Three common myths about VTE abound". First, that presentation with inpatient VTE is far more common than that with outpatient VTE; second, that when outpatient VTE does occur, it presents as a condition unprovoked by surgery or recent hospitalization; and third, that outpatient VTE, unlike inpatient VTE, cannot be prevented. "Spencer and colleagues, in their carefully executed and elegant study... shatter these myths," he observes.

Their study "establishes outpatient VTE as a common but often preventable public-health threat. The incidence of outpatient VTE rises when inpatient VTE prophylaxis is overlooked. Outpatient and inpatient VTE are coupled; they should no longer be placed in separate silos," he notes.

"These findings raise disturbing questions because evidence is plentiful to support the efficacy and safety of anticoagulant prophylaxis in hospitalized medical and surgical patients."

Proper VTE Prophylaxis Requires Evidence-Based Measures

In their related article, Wein and colleagues conducted a meta-analysis of 36 previously published randomized controlled trials in more than 48 000 patients, all of which compared medications used to prevent VTE with each other or with a control group of patients who did not receive prophylactic therapy.

Compared with the control group, unfractionated heparin (UFH) was associated with a 67% lower risk of DVT and a 36% lower risk of pulmonary embolism (PE), whereas low-molecular-weight heparin (LMWH) was associated with a 44% lower risk of DVT and a 63% lower risk of PE.

When the two forms of heparin were compared, LMWH was associated with a 32% lower risk of DVT and a 53% lower rate of hematoma at the injection site. Senior author Dr Henry Krum (Monash University) told heartwire that, overall, in the head-to-head comparisons "LMWHs were better for some parameters but certainly not for all."

Interestingly, prophylactic therapy was not associated with reduced mortality rates.

In his editorial, Goldhaber calls Wein et al's study a "methodologically rigorous meta-analysis of anticoagulant VTE prophylaxis trials in hospitalized medical patients. Their findings are similar to two other meta-analyses of anticoagulant prophylaxis of thromboembolism published this year," he notes.

"These results indicate that inpatient prevention of VTE is not a dichotomous yes-or-no metric. For pharmacological prophylaxis, this means ordering the right dose of the right medication at the right time for the proper duration (which may span the early hospitalization and the early period after hospital discharge," he notes.

Much Remains to Do, but Some Important First Steps Taken

Goldhaber says there are many questions still to be addressed. "Most pharmacological prophylaxis trials tested 7 to 10 days of anticoagulation therapy, but most contemporary hospitalizations are shorter," he points out.

"How often do patients who remain at risk at the time of hospital discharge receive VTE prophylaxis? When prophylaxis is inappropriately omitted at hospital discharge, are the overlooked patients the ones who also failed to receive VTE prophylaxis during hospitalization? Are these patients simply not being prescribed continued VTE prophylaxis that, objectively, is medically advisable? We must start collecting relevant data at the time of hospital discharge."

He notes, however, that things are starting to happen in this field. One strategy being employed is electronic alerts to physicians whose patients are at risk of VTE.

A separate approach involves nonprofit organizations such as the North American Thrombosis Forum (http://www.NATFonline.org), which, together with other outfits, has formed a new umbrella organization, the Venous Disease Coalition, which will be launched at the National Press Club in Washington, DC, on September 18, 2007.

Included in this are some important first steps taken by Medicare in the United States, he notes. The organization has recently launched two official quality VTE prophylaxis process measures - the first states that surgical patients will be expected to have recommended VTE prophylaxis ordered, and the second that they be expected to receive it within 24 hours before surgery to 24 hours after surgery.

"While these measures may seem modest, they constitute an important first official step in the eventual mandating of VTE prophylaxis," Goldhaber observes. But, he adds, "they do not cover hospitalized medical patients, who are at least as vulnerable to VTE as surgical patients are."

Guidelines are useful too, he says, "because the societies or groups that write them buy into the idea that preventing pulmonary embolism is important." However, whether they are implemented "remains to be seen," he comments.

Arch Intern Med. 2007;167:1451-1452, 1471-1486.