New guidelines address controversies in diagnosis and treatment of venous thromboembolism

Two companion papers, one in the Annals of Family Medicine and one in the Annals of Internal Medicine provide new guidelines for the diagnosis and treatment of VTE. Here are some highlights of the guidelines, which are available via the links above as open access full text.

The Wells prediction rules (provided in tables 1 and 2 of the diagnosis guideline) are validated by evidence. They do not perform as well in patients with co morbid conditions or prior VTE, in which cases clinical judgment becomes more important.

D-dimer testing is useful in selected patients with low probability Wells scores to exclude VTE and obviate further testing.

Between V/Q scanning and CT pulmonary angiography, available evidence suggests that clinical circumstances and judgment should dictate the initial selection of tests, neither of which is supported as the initial test of choice over the other. There is a popular misconception that CT is the clear method of choice. I addressed that misconception here and here.

Low molecular weight heparin (LMWH) is superior to unfractionated heparin (UFH) for treatment of DVT to decrease risk of mortality and major bleeding. (Editorial note: morbid obesity and kidney disease alter the pharmacokinetics of LMWH making laboratory monitoring necessary. Such monitoring requires special tests such as anti-Xa activity which are not available in real time in many hospitals. In such situations UFH should be used).

LMWH is acceptable, though not established as the clear choice over UFH, for initial treatment of PE. Published experience with LMWH for PE is limited.

Outpatient treatment of DVT with LMWH has been validated. The guideline stipulates that the necessary support system must be in place. (Editorial note: What’s an adequate support system? The devil’s in the details. If you’re a hospitalist or an ER physician considering outpatient treatment ask these questions: Does the patient have a payer source for the LMWH? Who will administer the shots--patient, family, home health nurse? Who will be responsible for following the INR during the transition from LMWH to warfarin?).

Compression stockings should be routinely used, to prevent post thrombotic syndrome (a point I made previously here).

Duration of warfarin therapy: 3 to 6 months if VTE is due to transient risk factors; at least 12 months (indefinitely) in cases of spontaneous recurrent VTE; consider “extended duration” treatment for initial spontaneous VTE. (“Extended duration” is poorly defined, but follow up periods in studies were as long as 4 years).

Long term treatment with LMWH “may be preferable” to warfarin in selected patients such as those with cancer and those whose INR is difficult to control.

For all the nuances and caveats, read both articles in their entirety.

(Hat tip to Physician’s First Watch and Retired Doc.