Original Research

Clinical Outcomes After Conversion from Low-Molecular-Weight Heparin to Unfractionated Heparin for Venous Thromboembolism Prophylaxis

Journal of Clinical Outcomes Management. 2017 August;24(8)

References

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In 2013, the pharmacy and therapeutics committee made a decision to encourage the use of UFH over LMWH for VTE prophylaxis by making changes to order sets to favor UFH over LMWH (enoxaparin). Given the uncertainty about excess risk of HIT, a monitoring work group was created to assess for any increase of either HIT or HITT that might follow, including any patient readmitted with thrombosis within 30 days of a discharge. In this paper, we report the impact of a hospital-wide conversion to UFH for VTE prophylaxis on the incidence of VTE, HIT, and HITT and acquisition costs of UFH and LMWH and use of alternative prophylactic anticoagulant medications.

Methods

Setting

Anne Arundel Medical Center is a 383-bed acute care hospital with about 30,000 adult admissions and 10,000 inpatient surgeries annually. The average length of stay is approximately 3.6 days with a patient median age of 59 years. Caucasians comprise 75.3% of the admitted populations and African Americans 21.4%. Most patients are on Medicare (59%), while 29.5% have private insurance, 6.6% are on Medicaid, and 4.7% self-pay. The 9 most common medical principal diagnoses are sepsis, heart failure, chronic obstructive pulmonary disease, pneumonia, myocardial infarction, ischemic stroke, urinary tract infection, cardiac arrhythmia, and other infection. The 6 most common procedures include newborn delivery (with and without caesarean section), joint replacement surgery, bariatric procedures, cardiac catheterizations, other abdominal surgeries, and thoracotomy. The predominant medical care model is internal medicine and physician assistant acute care hospitalists attending both medicine and surgical patients. Obstetrical hospitalists care for admitted obstetric patients. Patients admitted to the intensive care units had only critical care trained physician specialists as attending physicians. No trainees cared for the patients described in this study.

P&T Committee

The P&T committee is a multidisciplinary group of health care professionals selected for appointment by the chairs of the committee (chair of medicine and director of pharmacy) and approved by the president of the medical staff. The committee has oversight responsibility for all medication policies, order sets involving medications, as well as the monitoring of clinical outcomes as they regard medications.

Electronic Medical Record and Best Practice Advisory

Throughout this study period both pre-and post-intervention, the EMR in use was Epic (Verona WI), used for all ordering and lab results. A best practice advisory was in place in the EMR that alerted providers to all cases of thrombocytopenia < 100,000/mm ³ when there was concurrent order for any heparin. The best practice advisory highlighted the thrombocytopenia, advised the providers to consider HIT as a diagnosis and to order confirmation tests if clinically appropriate, providing a direct link to the HIT assay order screen. The best practice advisory did not access information from prior admissions where heparin might have been used nor determine the percentage drop from the baseline platelet count.

HIT Case Definition and Assays

The 2 laboratory tests for HIT on which this study is based are the heparin-induced platelet antibody test (also known as anti-PF4) and the serotonin release assay. The heparin-induced platelet antibody test is an enzyme-linked immunosorbent assay (ELISA) that detects IgG, IgM, and IgA antibodies against the platelet factor 4 (PF4/heparin complex). This test was reported as positive if the optical density was 0.4 or higher and generated an automatic request for a serotonin release assay (SRA), which is a functional assay that measures heparin-dependent platelet activation. The decision to order the SRA was therefore a “reflex” test and not made with any knowledge of clinical characteristics of the case. The HIT assays were performed by a reference lab, Quest Diagnostics, in the Chantilly, VA facility. HIT was said to be present when both a characteristic pattern of thrombocytopenia occurring after heparin use was seen [1]and when the confirmatory SRA was positive at a level of > 20% release.