American College of Physicians: Internal Medicine — Doctors for Adults ®


Internists play key role in DVT prevention

Experts urge wider prophylaxis but leave doctors to work out clinical details

From the March ACP Observer, copyright 2006 by the American College of Physicians.

By Bonnie Darves

The postoperative threat of venous thromboembolism (VTE) is fueling a debate that's reaching into internists' office: Should patients immobilized for more than a few days post-discharge be treated prophylactically for deep vein thrombosis (DVT) and its potentially deadly extension, pulmonary embolism (PE)?

DVT prophylaxis may include warfarin, shown here, which is cheaper than newer drugs.

While evidence shows that extending prophylaxis for orthopedic surgery patients works, specific guidance for medical patients is not as solid. "Everything apart from [hip surgery and fracture patients] becomes extrapolation," said Jack Hirsh, FACP, professor emeritus at McMaster University in Hamilton, Ontario. The problem is that physicians don't have as high an index of suspicion for DVT—which affects an estimated 2 million patients in the U.S. every year—in medical patients. (See "DVT fast facts.")

But recent guidelines from the American College of Chest Physicians (ACCP) tentatively point to subsets of medicine patients who may be candidates for both inpatient and extended prophylaxis. They include general- or gynecologic-surgery patients, cancer patients, and medical patients admitted for heart failure, respiratory illness, myocardial infarction or stroke. ACCP's 2004 guidelines note that between 50% and 70% of symptomatic thromboembolic events—and up to 80% of PEs—occur in nonsurgical patients.

Some physicians, who point to the lack of large clinical trials focused on the benefits of extended prophylaxis in these patients, are waiting for more evidence. But most experts agree there's enough emerging data to warrant more routine DVT assessment and a much more aggressive use of prophylaxis.

"What we're trying to say is, even if you don't believe the data that everybody who's at risk should get DVT prophylaxis, why not at least do risk stratification?" said Geno Merli, FACP, director of the internal medicine division at Thomas Jefferson University in Philadelphia and a leading researcher on thrombosis. "Choose those at high risk and give them prophylaxis like the [ACCP] guidelines tell us."

Who's at risk?

The ACCP guidelines call for DVT prophylaxis with low-dose unfractionated heparin (UH) or low-molecular-weight heparin (LMWH) "appropriate to their current risk state" in the following medical patients:

  • Acutely ill medical patients admitted for heart failure or severe respiratory disease who are confined to bed and have one of the following additional risk factors: active cancer, previous VTE, sepsis, acute neurological disease or inflammatory bowel disease.

  • Critical care patients and medically ill or post-operative ICU patients.

  • Cancer patients bedridden with acute medical illness, and those undergoing extensive surgery for malignancy or other surgical procedures, based on their risk state.

The guidelines also call for separate evaluation and monitoring of cancer patients who have special risks related to either treatment or cancer type—but don't offer detailed guidance. That leaves oncologists uncertain about when to extend DVT prophylaxis.

"What oncologists have done is to follow DVT prophylaxis [per the ACCP guidelines for medical patients] in the absence of contraindications," said Gary H. Lyman, FACP, professor of medicine and oncology at the University of Rochester in Rochester, N.Y. A practicing oncologist, Dr. Lyman is chairing an expert panel developing related guidelines for the American Society of Clinical Oncology.

"But because there's so little cancer-specific information and potentially additional risks associated with anticoagulation in cancer patients," he added, "the oncology community is looking for specific guidance on DVT prevention in this setting." (Surveys indicate that only 30% of oncologists order DVT prophylaxis for inpatients.)

The ACCP guidelines are similarly vague about medical inpatients, urging prophylaxis as appropriate—which amounts to using clinical judgment. And the guidance underscores another major problem: Some medical patients aren't receiving any prophylaxis, let alone extended therapy.

"It's great to say that some medical patients need prolonged prophylaxis, but let's just get them to receive prophylaxis in the hospital first," said general internist Robert C. Lavender, FACP, ACP's representative to the Coalition to Prevent Deep-Vein Thrombosis and a professor of medicine at the University of Arkansas for Medical Sciences in Little Rock. "That's not happening most of the time." (See "DVT awareness in the limelight.")

Part of the problem is that DVT prophylaxis is extended beyond discharge only some of the time for orthopedic surgery patients, Dr. Lavender noted—yet the median time to develop DVT in hip-replacement patients is 17 days, according to recent surveys.

As a result, internists may encounter these patients while they're still at high risk for DVT. "This is where it gets muddy, when you talk to general internists who may see the patients after discharge or treat them in a nursing home," said Franklin A. Michota, ACP Member, head of hospital medicine at the Cleveland Clinic Foundation in Cleveland and the Society of Hospital Medicine's representative to the DVT-prevention coalition. "They want to know how the inpatient DVT prophylaxis issue translates outside the walls of the hospital."

How long should prophylaxis continue, for example? The ACCP guidelines call for between 28 and 35 days for hip-fracture and joint-replacement patients but don't offer time frames for other patients. Dr. Michota favors extended DVT prophylaxis for periods ranging between one and four weeks, depending on the patient's status; other physicians may strive for a minimum seven- to 10-day extension in surgery patients and high-risk medical patients, transitioning those at continued high risk to 30 days. Still others work on a case-by-case basis.

Sometimes it's just a matter of extending prophylaxis until the patient is well, according to the ACCP guidelines. "If a patient is still bedridden or has a post-op infection, for example, it makes sense to continue prophylaxis until that risk dissipates," said Dr. Hirsh, the guidelines' chief author. "The principle that physicians should adhere to is this: If the patient is still at high risk [for a clot] based on the original condition or marked immobility, it makes sense to continue."

Dr. Michota agrees. He cited other patient risks that should be considered when deciding about prophylaxis extension, such as family history of thromboembolism, varicose veins, weight and birth control pill use.

"The take-home message for internists is that the same things that put people at risk for DVT in the hospital," he said, "may be risks for the homebound elderly and other patients they see in their office or elsewhere" after a hospitalization has occurred.

Putting DVT on the radar

Several large trials have demonstrated the benefits of venous thromboembolism prophylaxis in acutely ill medical inpatients in the hospital and after discharge, including the landmark 1999 Medenox study, the PREVENT study and the soon-to-be-published ARTEMIS trial.

Overall, these studies found that roughly 15% of patients who received no prophylaxis developed clots during hospitalization. "So with that finding—that if you did nothing to medically ill patients, 15% would get clots—you would think everybody would jump on this and apply prophylaxis," said Dr. Merli.

But that's not the case. Prophylaxis rates for inpatients remain abysmally low, according to a recent paper reporting data from the DVT-FREE Registry and published in the American Journal of Cardiology. Of the more than 5,000 patients in 183 U.S. hospitals who developed a blood clot, 58% had not received prophylaxis. A study published in the July 2005 issue of Archives of Internal Medicine found similarly low rates.

Experts say that several issues come into play. First, some physicians consider the 15% DVT rate low compared to the up to 75% clot rates in orthopedic-surgery patients, and figure their patients will be ambulatory soon enough.

Second, many institutions don't have standardized order sets for DVT prophylaxis or user-friendly patient risk-assessment mechanisms. And finally, patients are often so ill and comorbid on admission that DVT concerns don't hit the radar screen.

"I think that's the biggest barrier, that [DVT] is not something you think about because people are so sick when they are hospitalized," said Dr. Michota. "People don't just come in with pneumonia anymore. They've also got heart failure, chronic renal insufficiency and they're on 12 different medications."

Internists also are understandably concerned about the bleeding risk associated with some prophylactic agents, notably warfarin. Although the newer UH and LMWH medications and fondaparinux are associated with lower bleeding risk, physicians still prescribe anticoagulants reluctantly.

Another issue is that internists rarely see—in the literal sense—the DVT or the downstream effects when PE develops. According to Dr. Merli, "doctors don't think the risk is real because DVT is an asymptomatic disease." Yet the sequelae of DVT, even if it doesn't lead to PE, are considerable. About 30% of patients who incur DVT develop post-thrombotic syndrome, which can produce chronic edema and, in severe cases, venous ulceration.

Payment problems

Other issues hinder extended prophylaxis, including the fact that many insurers, including Medicare, don't cover the medications outside of the hospital or skilled-nursing setting.

Newer drugs can cost up to $1,000 a month at retail pharmacy rates, making them far more expensive than warfarin. Even with the new Medicare Part D drug benefit, patients may be reluctant to "use up" their benefit for prophylactic medications.

Joseph W. Stubbs, FACP, an ACP Regent and Albany, Ga., internist whose 10-physician group operates an anticoagulation clinic, has found one way to deal with that cost issue. He starts inpatients on combination warfarin and lovenox and then transitions those who don't have a high bleeding risk to warfarin alone. "Most of us favor the shot of LMWH over warfarin for safety's sake," he said, "but warfarin is cheaper for the patient who's picking up the tab."

Bradley T. Bryan, ACP Member, co-director of Providence St. Vincent Hospitalists in Portland, Ore., has found another solution: having drug companies provide the medications at no cost post-discharge for patients who meet income criteria. The group also uses DVT prophylaxis as part of its standing admission orders.

Other institutions are also attempting standardized approaches, including a risk stratification system to be used during medical admissions, a risk-assessment form and different types of computerized "prompts." (See "Web system reduces warfarin management risks.")

Incentives, guidance on the way

The biggest push to initial DVT prophylaxis and possible extension may come from oversight agencies. Medicare is considering the issue for future performance measures, while the Joint Commission on the Accreditation of Healthcare Organizations, in collaboration with the National Quality Forum, has developed consensus standards on VTE prevention and is developing a set of associated standardized inpatient measures. (Candidate measures are online.)

Help should also be coming early this summer when the EXCLAIM trial offers its long-awaited guidance on which medical patients should receive DVT prophylaxis after discharge. Begun in 2002, this randomized trial will include an estimated 10,000 patients. (Information on the trial is available.)

The findings could convince Medicare and other payers to pay for extended DVT prophylaxis—and finally persuade physicians to consider drug therapy in all at-risk patients, Dr. Merli said. In the interim, he urged internists to adhere to the ACCP guidelines.

"Until the EXCLAIM data comes out," he said, "we'll apply the CHEST guidelines and say 'treat them while in the house' and consider extending [prophylaxis] in other patient groups based on their clinical scenario."

At the same time, the battle to propel internists toward higher rates of inpatient and extended DVT prophylaxis may be a long one. Oregon's Dr. Bryan pointed to a recent grand rounds he hosted on the topic.

"I thought the [internists] would be the easiest group to convince that DVT is a problem, but they weren't at all," he said. "They questioned the literature and the validity of the problem, because a lot of [them] don't really see the impact of DVT complications."

Bonnie Darves is a freelance writer in Lake Oswego, Ore.

The information included herein should never be used as a substitute for clinical judgment and does not represent an official position of ACP.


DVT awareness in the limelight

March is DVT Awareness Month, part of a national initiative undertaken by the Coalition to Prevent Deep-Vein Thrombosis. The coalition has been formed to educate health care professionals, patients and policy makers, on DVT prevention and the problems of under-addressed patient risk and inadequate prophylaxis. A risk assessment tool and other helpful resources are available on the site.

Other online resources include:

  • Society of Hospital Medicine. The SHM Web site' venous thromboembolism section in the quality improvement resource rooms includes up-to-date literature, a DVT risk-assessment tool and prophylaxis order form, and an ask-the-expert forum.

  • Thrombosis Clinic. This exhaustive educational site provides a wide range of materials, from expert commentary and case studies to breaking news. The site also features several slide kits on identifying and managing medical inpatients at risk for DVT.

  • The site provides comprehensive, frequently updated evidence-based information on managing thrombosis and employing DVT prevention strategies.

  • ClotCare Online Resource. Primarily focused on the latest thinking and studies on antithrombotic and anticoagulant therapy, the site features distinct physician- and patient-targeted portals and includes links to several related Web sites.


Web system reduces warfarin management risks

When it comes to anticoagulation, the most affordable agent—warfarin—can be a patient-management nightmare.

Internists affiliated with Abington Memorial Hospital in Abington, Pa., have developed a virtual anticoagulation clinic to address those issues. Called WebINR, this interactive Web-enabled tool lets clinicians check whether patients on warfarin have shown up for monitoring and whether their international normalized ratio (INR) values are in range.

If patients are overdue for monitoring, the software generates an alert that displays the patients' names. The software also helps with dosage adjustments after patients have been seen. Hospital case managers fax the details of discharged patients to the practice and the WebINR coordinator "enters" the patient in the virtual clinic.

"The patients still have to show up, but if they don't, we have a clue," said Keith W. Sweigard, FACP, Abington's chief of internal medicine and medical director of the Abington Physician Network, a 30-practice organization affiliated with the hospital.

He also pointed to another advantage. "It gives us an administrative view of the data, which we need for quality improvement purposes."

Since its implementation in May 2002, Abington network practices have shown significant improvement in within-target-range INRs and complication rates, said Dr. Sweigard, whose software-engineer son, Brian, helped develop the product.

Abington now offers the tool for a fee. Training takes only 45 minutes, and the system doesn't require additional personnel to use, Dr. Sweigard noted.

For more information or to "demo" WebINR, go online.


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