Updated guidelines regarding the treatment of patients with venous thromboembolism advise abandoning the routine use of compression stockings for prevention of postthrombotic syndrome in patients who have had an acute deep vein thrombosis, according to Dr. Clive Kearon, lead author of the American College of Chest Physicians’ 10th edition of “Antithrombotic Therapy for VTE Disease” (Chest. 2015. doi: 10.1016/j.chest.2015.11.026).
The VTE guidelines include 12 recommendations. Two other key changes from the previous guidelines include new treatment recommendations about which patients with isolated subsegmental pulmonary embolism (PE) should, and should not, receive anticoagulant therapy, and as a recommendation for the use of non–vitamin K antagonist oral anticoagulants (NOACs) instead of warfarin for initial and long-term treatment of VTE in patients without cancer.
It is another of the group’s “living guidelines,” intended to be flexible, easy-to-update recommendations … based on the best available evidence, and to identify gaps in our knowledge and areas for future research,” Dr. Kearon of McMaster University, Hamilton, Ont., said in an interview.
“Clinicians and guideline developers would like clinician decisions to be supported by very strong, or almost irrefutable, evidence,” he said. ”It’s difficult to do studies that provide irrefutable evidence, however,” and most of the updated recommendations are not based on the highest level of study evidence – large, randomized controlled trials.
Nevertheless, “the quality of evidence that supports guidelines and clinical decision making is much better now than it was 20 or 30 years ago,” Dr. Kearon said, mainly because more recent studies are considerably larger and involve multiple clinical centers. Plus, “we’re continually improving our skills at doing high-quality studies and studies that have a low potential for bias.”
The old recommendation to use graduated compression stockings for 2 years after DVT to reduce the risk of postthrombotic syndrome was mainly based on findings of two small single-center randomized trials, published in the Lancet and Annals of Internal Medicine, in which patients and study personnel were not blinded to stocking use. Since then, a much larger multicenter, placebo-controlled trial found that routine use of graduated compression stockings did not reduce postthrombotic syndrome or have other important benefits in 410 patients with a first proximal DVT randomized to receive either active or placebo compression stockings. The incidence of postthrombotic syndrome was 14% in the active group and 13% in the placebo group – a nonsignificant difference. The same study also found that routine use of graduated compression stockings did not reduce leg pain during the 3 months after a DVT – although the stockings were still able to reduce acute symptoms of DVT, and chronic symptoms in patients with postthrombotic syndrome.
The recommendation to replace warfarin with NOACs is based on new data suggesting that the agents are associated with a lower risk of bleeding, and on observations that NOACs are much easier for patients and clinicians to use. Several of the studies upon which earlier guidelines were based have been reanalyzed, Dr. Kearon and his coauthors wrote. There are also now extensive data on the comparative safety of NOACs and warfarin.
“Based on less bleeding with NOACs and greater convenience for patients and health care providers, we now suggest that a NOAC is used in preference to VKA [vitamin K antagonist] for the initial and long-term treatment of VTE in patients without cancer,” they wrote.
The recommendation to employ watchful waiting over anticoagulation in some patients with subsegmental pulmonary embolism is based on a compendium of clinical evidence rather than on large studies. A true subsegmental PE is unlikely to need anticoagulation, because it will have arisen from a small clot and thus carry a small risk of progression or recurrence.
“There is, however, high-quality evidence for the efficacy and safety of anticoagulant therapy in patients with larger PE, and this is expected to apply similarly to patients with subsegmental PE,” the authors wrote. “Whether the risk of progressive or recurrent VTE is high enough to justify anticoagulation in patients with subsegmental PE is uncertain.”
If clinical assessment suggests that anticoagulation isn’t appropriate, these patients should have a confirmatory bilateral ultrasound to rule out proximal DVTs, especially in high-risk locations. If a DVT is detected, clinicians may choose to conduct subsequent ultrasounds to identify and treat any evolving proximal clots.
The guideline has been endorsed by the American Association for Clinical Chemistry, the American College of Clinical Pharmacy, the International Society for Thrombosis and Haemostasis, and the American Society of Health-System Pharmacists.
Dr. Kearon has been compensated for speaking engagements sponsored by Boehringer Ingelheim and Bayer Healthcare related to VTE therapy. Some of the other guideline authors also disclosed relationships with pharmaceutical companies.