Pharmacologic thromboprophylaxis is commonly prescribed to hospitalized patients with cancer without regard to concomitant risk factors for venous thromboembolism, according to a prospective, cross-sectional study of patients with cancer at five academic medical centers. Results were reported in the Journal of Clinical Oncology by Jeffrey I. Zwicker, MD, and colleagues at Beth Israel Deaconess Medical Center and Harvard Medical School in Boston and others affiliated with the five centers.
Data was collected for 775 consecutive patients admitted between January and June 2013. After accounting for the 247 patients (31.9%) with relative contraindications to pharmacologic thromboprophylaxis, the overall rate of pharmacologic thromboprophylaxis, was 74.2% (95% CI = 70.4%–78.0%; 392 of 528 patients). Previously reported rates from other studies of adherence to pharmacologic thromboprophylaxis recommendations range from 18% to 56%, the authors noted, and the variation could be explained in part by differences in data collection in studies that relied on retrospective analysis of large databases.
Authors of the current prospective study “identified several variables that influenced the probability of receiving pharmacologic thromboprophylaxis in hospitalized patients with cancer. Not surprisingly, patients with a prior history of thrombosis were most likely to receive pharmacologic thromboprophylaxis” (odds ratio [OR] = 5.80).
“However, other variables that influence the decision to use anticoagulant prophylaxis are less readily justified by the current literature,” the researchers wrote. “Patients with hematologic malignancies were less likely to receive thromboprophylaxis despite documented rates of venous thromboembolic events that were equal to or higher than those of many solid tumors” (OR = 2.34 for pharmacologic thromboprophylaxis for patients with nonhematologic vs hematologic malignancy).
“Similarly, the use of chemotherapy is an established risk factor for thrombosis, but patients were less likely to have received pharmacologic thromboprophylaxis in this setting compared with hospitalization for other reasons such as acute infection” (OR = 0.37 for patients admitted for cancer therapy vs those admitted for other reasons). “These data help to identify which populations of patients with cancer may be targeted for improved rates of thromboprophylaxis,” the authors stated.
“The common perception is that hospitalized patients, especially those with cancer, require pharmacologic thromboprophylaxis, as evidenced by the high rate of thromboprophylaxis in this study. However, a more measured approach to inpatient pharmacologic thromboprophylaxis is advocated, especially in a patient population considered high risk for in-hospital hemorrhage,” the investigators added.
[I]n the quest for strict compliance with federal mandates and competency measures and for minimizing legal liabilities, the lack of evidence supporting a one-size-fits-all approach to thromboprophylaxis for inpatients with cancer has been overlooked. These data bring into focus the deficiencies in both current clinical practice and evidence. There are little data to suggest that patients with a lower risk of cancer benefit from routine thromboprophylaxis. As advocated in the updated guidelines issued by the American Society of Clinical Oncology, additional assessments are needed to identify which patients with cancer with concomitant risk factors justify the use of (up to thrice) daily injectable anticoagulant, especially in a population considered at increased risk for in-hospital hemorrhage. Outcome studies are needed to further optimize pharmacologic thromboprophylaxis for inpatients with cancer; however, in the interim it is important that health systems and physicians be aware that current standard practice requires attention. ■
Zwicker JI, et al: J Clin Oncol. May 5, 2014 (early release online).