Norms and Consensus | The First Consensus on Lupus Anticoagulants in China Released

Recently, the first consensus on lupus anticoagulant testing and reporting, organized by the Thrombosis and Hemostasis Professional Committee of the Chinese Research Hospital Association, was published in the Chinese Journal of Laboratory Medicine. The consensus proposes standardized suggestions for the testing and reporting process of LA in China to ensure accurate management of related diseases and clinical conditions.

The detection of lupus anticoagulant (LA) is an important component of the experimental diagnosis of antiphospholipid syndrome and systemic lupus erythematosus. As it is a detection item based on coagulation time, LA results are easily affected by various anticoagulant drugs. LA has been recommended for various clinical situations, such as experimental diagnosis of antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE), risk assessment of venous thromboembolism (VTE), and explanation of prolonged activated partial thromboplastin time (APTT) for unknown reasons.

LA is not only found in SLE, but also in various other autoimmune states. In patients with infections, tumors, and the use of specific drugs, LA can also show transient positive results, and only a portion of SLE patients have LA; Secondly, the anticoagulant effect of LA is limited to prolonging phospholipid dependent clotting time in vitro, while in vivo, the sustained presence of LA is often associated with thrombosis.

Which patients need to be tested LA

01 Suspected APS patient:< 50 year old patients with ischemic stroke, transient ischemic attack, or other arterial thrombosis& Lt; 50 year old patients with unexplained venous thromboembolism (VTE) or uncommon site VTE; Repeated occurrence of arterial and venous thrombosis for unknown reasons; Patients with microvascular embolism; Obstetric complications such as recurrent miscarriage, stillbirth, premature birth, severe preeclampsia, and severe placental insufficiency.

02 Suspected SLE patients.

03 To be carried outVTE risk assessmentHospitalized patients based on Caprini score or Padua score.

04 Patients with immune thrombocytopenia, reticular plaques, or younger (< 50 years old) valvular heart disease, especially those with evidence of other systemic autoimmune diseases.

05 Patients with unexplained prolongation of coagulation time (usually activated partial thromboplastin time (APTT) alone), especially those who cannot be corrected by APTT prolongation correction tests. It should be noted that due to the varying sensitivity of different APTT reagents to LA, normal APTT results cannot exclude LA.

Precautions before LA testing

The use of anticoagulants, pregnancy, and other situations can lead to false positives or false negatives in LA testing. It is advisable to avoid sending tests in such situations as much as possible; When it is necessary to submit for testing, clinical doctors should carefully interpret the report results and, if necessary, analyze them together with the testing personnel.

Patients who receive anticoagulant drugs should pay attention to whether the test results are affected by anticoagulant drugs when sending them for testing. If necessary, a follow-up examination should be conducted to determine if there are any drug residues.

When the patient's medication or medical history is unclear, it is recommended to send both LA and routine coagulation tests, such as prothrombin time (PT), APTT, and thrombin time (TT), to provide background information on whether the patient has coagulation dysfunction or the use of anticoagulants.

LA detection method

Since no detection method is sensitive to all LA, it is recommended to choose at least two methods based on different principles to simultaneously detect LA. The commonly used methods are dRVVT and APTT sensitive to LA (it is recommended to use silica as the contact activator for APTT testing. The former uses viper venom to directly activate factor X, without being affected by the lack or inhibition of contact factors and factors VII, VIII, and IX; the latter uses contact activators to activate endogenous coagulation pathways, without being affected by factor VII deficiency or inhibition. Each method includes screening, confirmation, and mixed testing, and a positive result from either method indicates the presence of LA. In addition, detection methods such as diluted prothrombin time, Daban snake venom coagulation time, and snake vein enzyme coagulation time can also be used.

At present, there are two main LA testing protocols recommended by the Clinical and Laboratory Standards Institute (CLSI) and the International Society for Thrombosis and Hemostasis (ISTH) guidelines. One is a comprehensive trial: simultaneous LA screening and confirmation trials, and if necessary, mixed trials; Another type is sequence testing: screening tests are conducted first, and mixed and confirmatory tests are conducted after the results are positive. Any option chosen by the laboratory can be accepted.

The consensus clearly states that at least two methods based on different principles should be selected to simultaneously detect LA. The commonly used methods are diluted viper venom time (dRVVT) and LA sensitive APTT. At present, LA (dRVVT) and APTT, which have been launched by Chuangjing Biologics, can be used for clinical lupus anticoagulant testing and have been recognized by many third class users in China. To better meet clinical needs, the thrombophilia detection projects (PC, PS) and coagulation factors developed by Chuangjing Biotechnology are currently being applied for and will soon be launched. Please stay tuned!

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