This Article  • References  • Full text PDF  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citation map  • Citing articles on HighWire  • Contact me when this article is cited  Related Content  • Similar articles in this journal  Social Bookmarking   What's this?

Time to Reassess Guidelines for Heparin Assays

Brian A. Baker, PharmD; Michael D. Adelman, MD; Patricia A. Smith, MT; Janet C. Osborn, MT

Arch Intern Med. 1997;157(21):2475-2479.

Abstract
Background
In treating venous thromboembolic disorders, patient outcomes appear to correlate with heparin levels. Due to pharmacokinetic and pharmacodynamic variations, a relationship between heparin dose and level cannot be reliably predicted in individual patients. Some patients have low heparin levels despite therapeutic activated partial thromboplastin times (aPTTs), which may increase their risk for recurrent thromboembolism. Patients with high heparin requirements appear to have fewer bleeding episodes with heparin level—guided therapy. The aPTT does not reliably correlate with heparin blood concentrations or antithrombotic effects. Consequently, heparin therapy monitored with heparin levels may be more effective and safer.

Objectives
To prospectively determine whether (1) the aPTT therapeutic range adequately predicts heparin levels in 38 patients used to establish the therapeutic aPTT range as is currently recommended and (2) whether 3 paired sets of aPTT—antifactor Xa levels provide the basis for using aPTTs to predict subsequent heparin levels in individual patients (n=27) receiving intravenous heparin for coronary artery disease or venous thromboembolic disease.

Results
In the therapeutic aPTT range established, the R² value for the relationship was 0.4. Prediction intervals were wide. For an aPTT of 60 seconds, the 95% prediction interval estimates were heparin levels of 0.05 to 1.0 U/mL. In individual patients, the aPTT—antifactor Xa relationship had an average R² value of 0.75. There was no consistent relationship between the aPTT and anti-factor Xa level in a significant number of patients.

Conclusions
The aPTT does not appear to be a useful surrogate for heparin levels. These findings suggest that the current recommendations on the use of heparin levels should be expanded.

Arch Intern Med. 1997;157:2475-2479

Author Affiliations
From the Department of Pharmacy (Dr Baker) and the Division of Internal Medicine (Dr Adelman), Saint Vincent Health Center, and the Clinical Pathology Institute (Mss Smith and Osborn), Erie, Pa.

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter     What's this?

THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES

CardioWest (Jarvik) Total Artificial Heart: A Single-Center Experience With 42 Patients
Roussel et al.
Ann. Thorac. Surg. 2009;87:124-130.
ABSTRACT | FULL TEXT  

Parenteral Anticoagulants: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)
Hirsh et al.
Chest 2008;133:141S-159S.
ABSTRACT | FULL TEXT  

Acute ST-Segment Elevation Myocardial Infarction: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)
Goodman et al.
Chest 2008;133:708S-775S.
ABSTRACT | FULL TEXT  

How I treat venous thromboembolism in patients with cancer
Prandoni
Blood 2005;106:4027-4033.
ABSTRACT | FULL TEXT  

Anticoagulation Monitoring Part 2: Unfractionated Heparin and Low-Molecular-Weight Heparin
Spinler et al.
The Annals of Pharmacotherapy 2005;39:1275-1285.
ABSTRACT | FULL TEXT  

High-dose Intravenous Dalteparin Can be Monitored Effectively Using Standard Coagulation Times
Wilson et al.
CLIN APPL THROMB HEMOST 2005;11:127-138.
ABSTRACT  

Anticoagulation Monitoring
Smythe and Caffee
Journal of Pharmacy Practice 2004;17:317-326.
ABSTRACT  

Heparin and Low-Molecular-Weight Heparin: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy
Hirsh and Raschke
Chest 2004;126:188S-203S.
ABSTRACT | FULL TEXT  

Thrombolysis and Adjunctive Therapy in Acute Myocardial Infarction: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy
Menon et al.
Chest 2004;126:549S-575S.
ABSTRACT | FULL TEXT  

Anti-Xa Activity Relates to Survival and Efficacy in Unselected Acute Coronary Syndrome Patients Treated With Enoxaparin
Montalescot et al.
Circulation 2004;110:392-398.
ABSTRACT | FULL TEXT  

The Management of Venous Thromboembolic Disease in Older Adults
Rich
Journals of Gerontology Series A: Biological Sciences and Medical Sciences 2004;59:M34-41.
ABSTRACT | FULL TEXT  

Comparing Methods of Establishing the aPTT Therapeutic Range of Heparin
Liepman et al.
The Annals of Pharmacotherapy 2003;37:794-798.
ABSTRACT | FULL TEXT  

The Heparin Anti-Xa Therapeutic Range : Are We There Yet?
Smythe et al.
Chest 2002;121:303-304.
FULL TEXT  

Antithrombotic Therapy for Venous Thromboembolic Disease
Hyers et al.
Chest 2001;119 :176S-193S.
FULL TEXT  

Intravenous Thrombolysis in Acute Myocardial Infarction
Ohman et al.
Chest 2001;119 :253S-277S.
FULL TEXT  

Low molecular weight heparins for arterial thrombosis
Nenci and Minciotti
Vasc Med 2000;5:251-258.
ABSTRACT  

Direct Measurement of Unfractionated Heparin Using a Biochemical Assay
Mielke et al.
CLIN APPL THROMB HEMOST 1999;5:267-276.
ABSTRACT  

Activated Partial Thromboplastin Time vs Heparin Concentration
Mungall et al.
Arch Intern Med 1998;158:1273-1275.
FULL TEXT  

The Importance of Initial Heparin Treatment on Long-term Clinical Outcomes
Shojania et al.
Arch Intern Med 1998;158:1270-1272.
FULL TEXT