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A comparison between two activated protein C resistance methods as routine diagnostic tests for factor V Leiden
1Department of Haematology, Royal North Shore Hospital, Sydney, N.S.W., Australia.
British Journal of Haematology
|June 1, 1997
Summary
The Russell Viper Venom Time (RVVT) assay is superior for detecting Factor V Leiden mutation compared to the Activated Partial Thromboplastin Time (APTT) method, especially in complex patient groups. Modified RVVT offers reliable Factor V Leiden detection.
Area of Science:
- Hematology
- Thrombosis Research
- Diagnostic Laboratory Medicine
Background:
- Activated protein C (APC) resistance is commonly measured using Activated Partial Thromboplastin Time (APTT)-based assays.
- Russell Viper Venom Time (RVVT)-based systems offer an alternative method for assessing APC resistance.
- Pre-dilution with Factor V-deficient plasma can enhance the specificity of APTT-based assays for Factor V Leiden.
Purpose of the Study:
- To compare the efficacy of APTT-based and RVVT-based assays, with and without modifications, for detecting Factor V Leiden.
- To evaluate assay performance across diverse patient populations including asymptomatic individuals, thrombophilic patients, those on anticoagulants, and patients with lupus anticoagulant (LAC).
Main Methods:
- Comparative analysis of APTT-based and RVVT-based assays.
- Assessment of modified assays incorporating pre-dilution with Factor V-deficient plasma.
- Validation against genotyping for Factor V Leiden detection.
- Inclusion of patient cohorts: asymptomatic subjects, thrombophilic patients, patients on oral anticoagulants, and LAC-positive patients.
Main Results:
- The RVVT-based assay demonstrated superior separation of normal individuals from those with Factor V Leiden mutation compared to the APTT-based method.
- Both modified assays achieved 100% sensitivity and specificity for Factor V Leiden detection, confirmed by genotyping.
- The modified RVVT assay provided better discrimination between normal and Factor V Leiden positive individuals.
- The RVVT-based assay proved more reliable in the presence of lupus anticoagulant (LAC) antibodies, which interfere with APTT-based systems.
Conclusions:
- The RVVT-based assay is a more suitable method for screening Factor V Leiden, particularly in complex patient groups.
- Modified RVVT assays offer a reliable and accurate diagnostic tool for Factor V Leiden detection across various clinical scenarios.
- The phospholipid-rich nature of the RVVT assay makes it advantageous in patients with LAC, unlike the APTT-based system.