Extended Duration Thromboprophylaxis for Venous Thromboembolism
Orlando—Patients with venous thromboembolism (VTE) who took extended duration thromboprophylaxis had an incremental cost-effectiveness ratio of $8123 per quality-adjusted life year (QALY), according to a cost-effectiveness decision tree model. The threshold for the relative cost-effectiveness was a VTE incidence exceeding 2.53%.
James C. Iannuzzi, MD, the study’s lead author, presented the results at DDW during a plenary session.
“I think there is clear evidence as a payer that they should cover extended duration thromboprophylaxis, especially if you only consider the cost threshold,” he said.
After Acting Surgeon General Steven K. Galson released a call to action to prevent deep vein thrombosis (DVT) and pulmonary embolism (PE) in September 2008, there were numerous inpatient prophylaxis initiatives, Dr. Iannuzzi said. However, the period of risk of developing DVT or PE extends beyond the inpatient setting. VTE consists of DVT and PE, he added.
Previous randomized control trials have demonstrated the efficacy of extended duration thromboprophylaxis, which Dr. Iannuzzi defined as 28 days of low molecular weight heparin (LMWH) following surgery. However, he said that most patients do not adhere to guidelines from the National Comprehensive Cancer Network (NCCN) and the American College of Chest Physicians (ACCP). The NCCN suggests using the same approach for all abdominal and pelvic oncologic resections, but the ACCP recommends a more selective approach for high risk patients and considering patient preferences on costs. LMWH costs up to $1200 for a 28-day treatment course, according to Dr. Iannuzzi.
“It really becomes a balance between preventing VTE and the trade-offs of cost and also the discomforts [for] patients, particularly self-injections,” Dr. Iannuzzi said.
To develop their model, the authors conducted a literature review and made estimates on costs and utilization. They assessed costs in terms of 2013 US dollars, used QALY as the measure of effectiveness, and evaluated cost effectiveness using the incremental cost effectiveness ratio, which Dr. Iannuzzi defined as the difference in cost divided by the difference in effectiveness. They set the willingness to pay threshold at $50,000 per QALY.
In the model, patients undergoing oncologic abdominal surgery could receive 7 days of inpatient prophylaxis or 28 additional days of LMWH. At baseline, the authors made assumptions on utilization and the probability of VTE, medication compliance, death, and other factors. They used a database to estimate the costs of PE ($23,248.23), DVT ($21,539.76), post thrombotic syndrome ($14,362.71), generic LMWH ($705.74), branded LMWH ($871.74), and annual medical costs ($680).
For branded LMWH, the threshold at which extended duration thromboprophylaxis became the most cost minimizing was at 1.2% risk of developing postdischarge VTE. For generic LMWH, the threshold at which extended duration thromboprophylaxis became the most cost minimizing was at 0.2% risk of developing postdischarge VTE. The cost-effectiveness threshold was found at 1.65% risk of developing postdischarge VTE for branded LMWH and at 0.88% risk of developing postdischarge VTE for generic LMWH.
“The cost of the drug made a large difference,” Dr. Iannuzzi said.
Dr. Iannuzzi said more studies should be undertaken to evaluate the quality of life after abdominal surgery. He also suggested providers should implement risk scores to determine patients’ risks for VTE after being discharged.
The study had some "major" limitations, acccording to Dr. Iannuzzi, particularly because it was a simplified model. He noted that there was also a lack of utility weights for abdominal surgery.
