Prior use of therapeutic anticoagulation does not protect against COVID-19-related clinical outcomes in hospitalised patients

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Use of therapeutic anticoagulation prior to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was associated with a lower risk for pulmonary embolism, but not a decreased risk for other coronavirus disease 2019 (COVID-19)-related outcomes in hospitalised COVID-19 patients, including in-hospital mortality, according to a study published in the British Journal of Clinical Pharmacology.

“The acute inflammatory phenomenon in COVID-19 amplifies hypercoagulability and increases the risk of thrombosis even under prophylaxis of low molecular weight heparin (LMWH). It has been hypothesised that therapeutic anticoagulation used prior to infection could improve the prognosis of COVID-19 by hampering coagulation activation,” wrote Janneke P Spiegelenberg, Radboud University Medical Center, Nijmegen, Netherlands, and colleagues. “Several studies investigated the association between therapeutic anticoagulation prior to hospitalisation and mortality with ambivalent results, probably due to methodological limitations.”

The study involved 1,154 patients with COVID-19 admitted to 6 hospitals in the Netherlands between March 1 and May 31, 2020. Of the patients, 92 (8%) were treated with vitamin K antagonists (VKA), 98 (8%) were on direct oral anticoagulants (DOAC), while the remaining 964 (84%) patients did not use therapeutic anticoagulation prior to COVID-19 diagnosis. For patients using therapeutic anticoagulation prior to COVID-19 diagnosis, treatment was continued during hospitalisation. Meanwhile, among patients who did not use therapeutic anticoagulation prior to admission, 856 (89%) received prophylactic LMWH during hospitalisation.

Subsequent propensity score matching included 164 patients with prior use of therapeutic anticoagulation and 410 without therapeutic anticoagulation prior to admission. The median age of this propensity score-matched cohort was 76 years.

The primary outcome was all-cause in hospital mortality, while secondary outcomes included admission to the intensive care unit (ICU), need for invasive mechanical ventilation, imaging-proven pulmonary embolism, and length of hospital stay.

In the propensity score matched analyses, the researchers observed no associations between prior use of therapeutic anticoagulation and overall mortality (relative risk [RR] 1.02, 95% confidence interval [CI] 0.80-1.30), ICU admission (RR 0∙82, 95% CI 0∙51-1∙31), need for invasive mechanical ventilation (RR 0∙95, 95% CI 0∙55-1∙65), length of hospital stay (median, 7.0 vs 7.0 days, P = 0.69). Nonetheless, a lower risk of pulmonary embolism (RR 0.19 (95% CI; 0.05-0.80) was observed among patients who had prior use of therapeutic anticoagulation compared with those without prior use of therapeutic anticoagulation.

In addition, the researchers did not observe differences in outcomes between DOAC or VKA-treated subgroups.

“This study provides convincing evidence that therapeutic anticoagulation used prior to infection is associated with a decreased risk of pulmonary embolism, but not with mortality and other disease severity parameters” the authors concluded.