Thromboprophylaxis makes good economic, clinical sense for VTE inpatients

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Thromboprophylaxis is underutilized in medical inpatients, even though the clinical and economic impact of venous thromboembolism (VTE) is significant, according to a retrospective analysis published in the June issue of the American Journal of Managed Care.

An estimated 200,000 to 600,000 Americans develop VTE each year. It is estimated that more than three-fourths of U.S. hospitalized patients have at least one risk factor for VTE and 48 percent have two or more risk factors, according to the study authors. VTE risk is lower in medical patients than in surgical patients, but still substantial (10 to 20 percent), they wrote. In addition, there is increasing evidence that medical patients are less likely than surgical patients to receive thromboprophylaxis, even when it is indicated or recommended.

Thus, Onur Baser, PhD, an economist and adjunct professor of internal medicine at the University of Michigan at Ann Arbor, and colleagues sought to evaluate the real-world effect of pharmacologic VTE prophylaxis among medical inpatients on the incidence and timing of VTE, readmission due to VTE, bleeding events and cost of care in the 30, 90 and 180 days in the post-discharge period after the initial (index) admission.

This was a retrospective analysis of patient-level data from the MarketScan Hospital Drug Database (HDD) and linked outpatient files from the MarketScan Commercial and Medicare Supplemental Database from Thomson Reuters for calendar years 2005 to 2007.

The researchers analyzed data from patients admitted to the hospital from 2005 to 2007 with a primary diagnosis of chronic heart failure, thromboembolic stroke, severe lung disease, acute infection or cancer, according to whether they received VTE prophylaxis or not. They also analyzed the number of VTE events, time to VTE event, length of hospital stay and number of major or minor bleeding events from the index date until the end of follow-up (180 days post-discharge) or death.

Overall, 53.6 percent of the patients received VTE prophylaxis. When used, prophylaxis significantly reduced the incidence of VTE compared with no prophylaxis (0.06 vs. 3.44 percent, respectively) and increased the median time to VTE (182 vs. 27 days, respectively). Prophylaxis also significantly reduced the incidence of VTE in the 180 days post-discharge.

The readmission rates were similar between groups, the study authors reported. Major bleeding occurred in 1.57 percent of patients receiving low molecular weight heparin plus warfarin vs. less than 0.6 percent receiving any other form of prophylaxis. The development of VTE or major or minor bleeding events significantly increased total medical costs vs. no VTE events or no bleeding events.

More specific to costs, Baser et al reported that the per patient cost of medical care from admission until 30, 90 or 180 days post-discharge was significantly higher in patients who developed VTE compared with those who did not develop VTE. Similarly, the per patient cost of medical care during these time periods was significantly higher in patients who developed major or minor bleeding compared with those who did not develop bleeding, they wrote.

Based on their findings, the researchers concluded that this study confirms that thromboprophylaxis is underutilized in medical patients in the U.S. The study also demonstrated that anticoagulant therapy reduces the incidence of and prolongs the time to VTE among a broadly representative sample of medical inpatients, according to the study authors, but does not significantly increase risk of major or minor bleeding.

“Combining warfarin with LMWH [low-molecular weight heparin] or unfractionated heparin does not reduce risk of VTE but does increase risk of bleeding relative to LMWH monotherapy,” Baser and colleagues concluded. “Risk-adjusted total healthcare costs are significantly higher for medical patients with versus without VTE, and for those who develop bleeding versus those who do not.  Overall, our data show that the occurrence of VTE in medical patients not only has a major clinical impact, but it also increases the economic burden on the U.S. healthcare system.”