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Prothrombotic autoantibodies were elevated in COVID-19 and linked to development of thrombosis, a small observational study showed.

Lupus anticoagulant (LA) appeared in 44% of COVID-19 patients tested versus 22% of other patients (30 of 68 vs 27 of 119, P=0.002), according to Morayma Reyes Gil, MD, PhD, of Montefiore Medical Center in New York City, and colleagues.

In the COVID-19 group, 63% of the LA-positive patients had documented arterial or venous thrombosis compared with 34% of the LA-negative patients (P=0.03), the group reported in .

C-reactive protein (CRP) levels were higher with LA positivity but not linked with thrombosis. On the other hand, LA remained a significant independent predictor of thrombosis after adjusting for CRP, with an odds ratio of 4.39.

"LA-positive individuals have a marked risk of arterial and venous thrombosis, and therapeutic anticoagulation should be considered in these patients," the group concluded.

of COVID-19 patients have also found high LA-positive prevalence. For example, an observational study that is often referenced in support of inpatient anticoagulation for COVID-19, based on a suggestion of mortality benefit, found 91% LA positive among the 34 patients tested for it, significantly more than seen in historical controls.

LA has also been associated with thrombotic events in systemic lupus erythematosus, but the autoantibodies are not specific to lupus.

Gil and colleagues' retrospective study included 187 patients with LA testing ordered from March 1 to April 30, 2020, at Montefiore Medical Center. The comparator group for the COVID-19 patients was the 119 who were not tested, or were negative by PCR testing, for the SARS-CoV-2 virus.

Mean prothrombin time and partial thromboplastin time (PTT) were more prolonged in LA-positive compared with LA-negative patients, the researchers noted.

LA positivity was determined by the dilute Russell viper venom time, because PTT-based tests are interfered with by the elevated CRP levels seen in most patients with COVID-19.

LA status didn't correlate with gender, race, ethnicity, ventilation, mortality, or anticoagulation at the time of thrombosis.

Study limitations included a small sample size and inability to control time of LA testing from admission to outcome (mortality and thrombosis).

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