Response to "Lupus anticoagulant is frequent in patients with Covid-19" (JTH-2020-00483).

We appreciate the opportunity to respond to the letter from Dr. Inès Harzallah et al. I have also performed antiphospholipid antibody assays including lupus anticoagulant (LAC), anticardiolipin, and anti–β2‐glycoprotein I in dozens of our patients; however, very few of them got positive results. We do not believe that antiphospholipid antibody exists universally in COVID‐19 patients. In addition, two of the three reported cases with antiphospholipid antibodies mentioned in the letter also seem to meet the International Society on Haemostasis and Thrombosis criteria of disseminated intravascular coagulation, the causality between antiphospholipid antibodies and thrombosis in these cases is still uncertain.

Both the International Society on Haemostasis and Thrombosis and the Clinical and Laboratory Standards Institute guidelines have urged caution when interpreting LAC results in patients receiving anticoagulants. , Given common use of low molecular weight heparin and unfractionated heparin for thromboprophylaxis in COVID‐19 inpatients, false‐positive results resulting from interference of these anticoagulants may be an important reason for the high positive rate of LAC mentioned in this letter. It has been recommended that the blood should be drawn for LAC testing after 12 hours since the last dose of low molecular weight heparin and 24 hours since that of rivaroxaban. ,

CONFLICT OF INTEREST

None declared.