Effect of a dalteparin prophylaxis protocol using anti-factor Xa concentrations on venous thromboembolism in high-risk trauma patients.
BACKGROUND
Low anti-factor Xa (anti-Xa) concentrations with twice-daily enoxaparin are associated with venous thromboembolism (VTE) in high-risk trauma patients. Concerns have been raised with once-daily dalteparin regarding effectiveness and achievable anti-Xa concentrations. The purpose of this before-and-after study was to evaluate the effectiveness of a VTE prophylaxis protocol using anti-Xa concentrations and associated dalteparin dose adjustment in high-risk trauma patients.


METHODS
Adult trauma patients receiving VTE chemoprophylaxis and hospitalized for at least 3 days were prospectively followed during two 6-month epochs before (PRE) and after (POST) implementation of anti-Xa monitoring. In both groups, high-risk patients received dalteparin 5,000 U subcutaneously once daily; low-risk patients received subcutaneous unfractionated heparin. High-risk POST patients with anti-Xa less than 0.1 IU/mL 12 hours after initial dalteparin dose received dalteparin every 12 hours. All patients underwent routine VTE ultrasound surveillance of the lower extremities. The primary outcome was incidence of VTE.


RESULTS
A total of 785 patients (PRE, n = 428; POST, n = 357) were included. Demographics, injury patterns, Injury Severity Score (ISS), red blood cell transfusions, intensive care unit and hospital stays, and mortality did not differ between groups. Overall, POST patients had lower VTE (7.0% vs. 13%, p = 0.009) including acute VTE (6.4% vs. 12%, p = 0.01) and proximal deep vein thromboembolism (2.2% vs. 5.7%, p = 0.019). Between high-risk patients, VTE occurred in 53 (16.3%) PRE compared with 24 (9.0%) POST patients (p = 0.01); there was no difference in VTE between low-risk patients (PRE, 2.0% vs. POST, 1.1%; p = 0.86). Among 190 high-risk POST patients with anti-Xa, 97 (51%) were less than 0.1 IU/mL. Patients with low anti-Xa had higher rates of VTE (14.0% vs. 5.4%, p = 0.05) and deep vein thromboembolism (14.4% vs. 3.2%, p = 0.01). Younger age (odds ratio, 0.97; 95% confidence interval, 0.95-0.99) and greater weight (odds ratio, 1.02; 95% confidence interval, 1.00-1.03) predicted low anti-Xa on multivariate regression.


CONCLUSIONS
A VTE prophylaxis protocol using anti-Xa-based dalteparin dosage adjustment in high-risk trauma patients was associated with decreased VTE. Once-daily dalteparin 12-hour anti-Xa concentrations are suboptimal in a majority of patients and associated with VTE.


METHODS
Therapeutic study, level IV.
From the Departments of Pharmacy Services and Pharmacy Practice (M.E.D., E.W.M., C.A.D., N.E.E., S.P.K., D.M.L.), Department of Nursing (K.M.B., J.A.L., E.A.K.), and Division of Trauma and Critical Care (K.P.A., D.J.H., B.R.H.R.), Department of Surgery, University of Cincinnati Medical Center, Cincinnati, Ohio.
Molly E
ME
Droege
Eric W
EW
Mueller
Kelly M
KM
Besl
Jennifer A
JA
Lemmink
Elizabeth A
EA
Kramer
Krishna P
KP
Athota
Christopher A
CA
Droege
Neil E
NE
Ernst
Shaun P
SP
Keegan
Dave M
DM
Lutomski
Dennis J
DJ
Hanseman
Bryce R H
BR
Robinson
D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage; D015331:Cohort Studies; D017985:Dalteparin / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D015951:Factor Xa / Q000032:analysis / Q000187:drug effects*; D005260:Female; D005500:Follow-Up Studies; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage; D006801:Humans; D015994:Incidence; D007279:Injections, Subcutaneous; D015601:Injury Severity Score; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D011446:Prospective Studies; D012016:Reference Values; D018570:Risk Assessment; D013997:Time Factors; D014193:Trauma Centers; D016896:Treatment Outcome; D054556:Venous Thromboembolism / Q000188:drug therapy / Q000453:epidemiology* / Q000517:prevention & control*; D014947:Wounds and Injuries / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality; D055815:Young Adult
D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D015951:Factor Xa; D017985:Dalteparin