Related Experiment Videos
Correlation between activated clotting time and activated partial thromboplastin times
Maureen A Smythe1, John M Koerber, Sandra N Nowak
1Department of Pharmaceutical Services, William Beaumont Hospital, 3601 W. 13 Mile Rd., Royal Oak, MI 48073-6769, USA. msmythe@beaumont.edu
The Annals of Pharmacotherapy
|January 31, 2002
Summary
This study found laboratory aPTT better correlates with heparin levels than bedside ACT or aPTT. Clinical decisions on heparin dosing differed over a third of the time between ACT and aPTT tests.
Area of Science:
- Clinical Chemistry
- Hematology
- Pharmacology
Background:
- Heparin anticoagulation requires monitoring via clotting time tests.
- Activated clotting time (ACT) and activated partial thromboplastin time (aPTT) are commonly used, but their correlation with heparin concentration and each other varies.
- Understanding these correlations is crucial for accurate heparin dosing and patient safety.
Purpose of the Study:
- To assess the correlation between heparin concentration and clotting time tests (ACT and aPTT).
- To evaluate the correlation between ACT and aPTT results across different instruments.
- To compare clinical decisions on heparin dosage adjustments based on ACT versus aPTT.
Main Methods:
- Retrospective analysis of a large database including heparin concentrations, ACT, and aPTT results from multiple instruments.
- Calculation of correlation coefficients between heparin levels and clotting times.
- Comparison of heparin dosage adjustment decisions derived from ACT and aPTT results.
Main Results:
- Moderate to strong correlations were observed between heparin concentration and clotting time tests (r = 0.72 for ACT, r = 0.74-0.86 for aPTT).
- Laboratory-based aPTT showed the highest correlation with heparin concentration.
- Correlations between ACT and aPTT ranged from r = 0.64-0.67, with similar values across different aPTT instruments.
- Clinical decisions for heparin adjustment based on ACT agreed with aPTT-based decisions only 59-63% of the time.
Conclusions:
- Laboratory aPTT demonstrates a superior correlation with heparin concentration compared to bedside aPTT and ACT.
- ACT and aPTT show moderate correlation, with similar performance across different aPTT devices.
- Discrepancies in clinical decisions based on ACT versus aPTT highlight potential variability in heparin management.