Presentation Transcript

  1. SCINTIGRAPHY OF ACUTE DEEP VENOUS THROMBUS RAD605.016 ______________________________________________________________________ COVERAGE: Scintigraphic imaging of acute deep venous thrombus in the lower extremities MAY BE ELIGIBLE FOR COVERAGE in patients with signs and symptoms of acute deep venous thrombus. Scintigraphic imaging of the lower extremities for asymptomatic patients at risk of acute deep venous thrombus, is considered investigative and IS NOT ELIGIBLE FOR COVERAGE. ______________________________________________________________________ DESCRIPTION: Deep vein thrombosis (DVT) is a common occurrence. It is estimated that in the United States approximately 5 million patients experience one or more episodes of DVT each year, resulting in over 500,000 cases of pulmonary embolism and 100,000 deaths. Prompt treatment of acute thrombus is considered essential in order to initiate anticoagulation or thrombolytic therapy to prevent the serious consequences of pulmonary embolus. Radiographic evaluation of deep venous thrombus is performed both in symptomatic and asymptomatic patients at high risk of venous thrombus, i.e., after orthopedic surgery. Contrast venography is considered the gold standard of diagnosis, but this invasive procedure is not routinely used. Duplex ultrasonography is probably the most common noninvasive technique used, followed by impedance plethysmography. Ultrasonography is thought to have excellent sensitivity and specificity in the thigh, but poor diagnostic accuracy below the knee. Both techniques provide indirect evidence of thrombus by imaging an alteration in blood flow and thus cannot distinguish between acute and chronic thrombus. Direct detection of acute venous thrombus has been investigated using intravenously injected radiolabeled synthetic peptides that bind with high affinity to receptors expressed on activated platelets. In 1999, the FDA approved the radiopharmaceutical peptide apcitide (AcuTect) for use in the scintigraphic imaging of acute venous thrombosis in the lower extremities of patients who have signs and symptoms of acute thrombophlebitis. Apcitide binds to glycoprotein IIb/IIIa fibrinogen receptors, which are expressed on the surface of activated platelets, thus making the radiopharmaceutical specific for acute, not chronic thrombus. ______________________________________________________________________ RATIONALE: The following data is based on the package insert of AcuTect. Two multicenter clinical studies included 243 patients with signs and symptoms of acute thrombus that underwent evaluation with scintigraphic imaging compared with contrast venography, considered the gold standard. The primary outcome of the studies was agreement between the interpretations of the blindly read scintigraphic and contrast venography studies. The criterion for efficacy end point was pre-set at 75% agreement, with the lower limit of the 95% confidence

  2. interval being 60%. This agreement rate took into account the blind read variability of venography due to the adverse impact of the reader being blinded to the clinical information on the patient. The agreement rate between the results of scintigraphy vs. venography met this criterion. It should be noted that the FDA-labeled indications are limited to symptomatic patients, and the data presented to the FDA focused on symptomatic patients also. There are no data regarding the use of scintigraphic imaging in asymptomatic patients. Asymptomatic patients may represent a large percentage of patients undergoing imaging for DVT as a "rule out" test. For example prior to hospital discharge after orthopedic procedures such as arthroplasties, many asymptomatic patients may undergo Doppler ultrasonography to rule out the presence of a thrombus. Data regarding this application of scintigraphic imaging have not been published. The FDA labeling also states "How negative AcuTect images should be used in the diagnostic evaluation or therapeutic management of patients with suspected acute venous thrombosis has not been studied." In addition, there are no data regarding the diagnostic performance of scintigraphic imaging compared with Duplex ultrasonography, a more commonly used diagnostic technique than contrast venography. Therefore, it is not known whether the evaluation of DVT is improved by routinely performing both ultrasonography and scintigraphic imaging in the setting of indeterminate or nondiagnostic ultrasonography in symptomatic patients. ______________________________________________________________________ DISCLAIMER: State and federal law, as well as contract language, including definitions and specific inclusions/exclusions, takes precedence over Medical Policy and must be considered first in determining coverage. The member’s contract benefits in effect on the date that services are rendered must be used. Any benefits are subject to the payment of premiums for the date on which services are rendered. Medical technology is constantly evolving, and we reserve the right to review and update Medical Policy periodically. HMO Blue Texas physicians who are contracted/affiliated with a capitated IPA/medical group must contact the IPA/medical group for information regarding HMO claims/reimbursement information and other general polices and procedures. ______________________________________________________________________ Blue Cross and Blue Shield of Texas, a Division of Health Care Service Corporation, a Mutual Legal Reserve Company* Southwest Texas HMO, Inc.* d/b/a HMO Blue Texas * Independent Licensees of the Blue Cross and Blue Shield Association ______________________________________________________________________ Posted Jan. 7, 2003