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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Order Set Modifications

After the P&T committee decision to emphasize UFH for VTE prophylaxis in October 2013, the relevant electronic order sets were altered to highlight the fact that UFH was the first choice for VTE prophylaxis. The order sets still allowed LMWH (enoxaparin) or alternative anticoagulants at the prescribers’ discretion but indicated they were a second choice. Doses of UFH and LMWH in the order sets were standard based upon weight and estimates of creatinine clearance and, in the case of dosing frequency for UFH, based upon the risk of VTE. Order sets for the therapeutic treatment of VTE were not changed.

Data Collection and Analysis

The clinical research committee, the local oversight board for research and performance improvement analyses, reviewed this project and determined that it qualified as a performance improvement analysis based upon the standards of the U.S. Office of Human Research Protections. Some data were extracted from patient medical records and stored in a customized and password-protected database. Access to the database was limited to members of the analysis team and stripped of all patient identifiers under the HIPAA privacy rule standard for de-identification from 45 CFR 164.514(b) immediately following the collection of all data elements from the medical record.

An internal pharmacy database was used to determine the volume and actual acquisition cost of prophylactic anticoagulant doses administered during both pre- and post-intervention time periods. To determine if clinical suspicion for HIT increased after the intervention, a definitive listing of all ordered HIT assays was obtained from laboratory billing records for the 9 months (January 2013–September 2013) before the conversion and for 25 months after the intervention (beginning in November 2013 so as not to include the conversion month). To determine if the HIT assays were associated with a higher risk score, we identified all cases in which the HIT assay was ordered and retroactively measured the probability score known as the 4T score [1].Simultaneously, separate clinical work groups reviewed all cases of hospital-acquired thrombosis, whatever their cause, including patients readmitted with thrombosis up to 30 days after discharge and episodes of bleeding due to anti-coagulant use. A chi square analysis of the incidence of HIT pre- and post-intervention was performed.

Results

Heparin Use and Acquisition Costs

Annual hospital admissions and patient-days both increased 3% during the study time period to 29,975 annual adult admissions and 96,426 hospital days. However, the number of patients receiving any prophylactic anticoagulant increased 15% over the time period as a result of a simultaneous anti-VTE education campaign. After the modification in order sets there was a rapid increase in orders for prophylactic UFH and a corresponding decrease in the use of LMWH ( Figure 1 ). A few patients received both at different times during their hospitalization. Prophylactic UFH orders increased from 43% of all prophylactic use pre-intervention to 86% by the second year of the intervention. There was a corresponding reduction in use of LMWH from 53% of all prophylaxis orders to 11% after the intervention. Other anticoagulants, fondaparinux and bivalrudin, together composed 5% and 4% of all prophylactic heparin in the pre- and post-intervention time periods, respectively. Pharmacy acquisition costs averaged $3.50 for daily doses of heparin and $24 for LMWH. With the shift in ordering pattern, acquisition costs of prophylactic LMWH fell by $165,000 annually with a concurrent offsetting increase in acquisition costs of UFH of $34,000 for a net savings of $131,000. The median duration of use was 3.5 days and 3.0 days for UFH and LMWH, respectively. Only 25% of treated patients had heparin exposure of > 5 days. Bleeding complications from any prophylaxis regimen were < 0.5% in both pre- and post-intervention time periods.

HIT Assays and Incidence of HIT and HITT