Lower limb deep vein thrombosis common in COVID-19

Deep vein thrombosis (DVT) is not an uncommon occurrence among patients with COVID-19 pneumonia, and is often asymptomatic, a recent study has found.

“A surveillance protocol by serial compression ultrasound (CUS) of the lower limbs is useful to timely identify DVT that would go otherwise largely undetected,” the researchers said.

They conducted a multicentre, prospective analysis of 227 patients (mean age 72±13 years, 56.8 percent men) with moderate-to-severe COVID-19, screened for DVT of the lower limbs using serial CUS. Those on low-, intermediate-, or high-dose medication with enoxaparin or fondaparinux were considered to be under anticoagulation. The primary outcome was the diagnosis of DVT.

All patients received anticoagulants, with enoxaparin being the most common (n=217; 95.6 percent). Ultimately, 31 patients were diagnosed with DVT, yielding an incidence rate of 13.7 percent. DVT was proximal in 14 patients (6.2 percent), while it involved veins of the infrapopliteal district in 17 (7.5 percent); overall, four patients had bilateral DVT.

Notably, only two cases of DVT were symptomatic; the remaining 29 patients presented with no outward signs of thrombosis.

While patients who developed DVT received significantly lower mean daily doses of enoxaparin than non-DVT counterparts (47±23 vs 66±38 mg/day; p=0.042), in general, anticoagulation regimens were comparable between groups and could not explain the onset of DVT.

Receiver operating characteristic curve analysis instead pointed to a peak D-dimer concentration >2,000 ng/mL as the strongest predictor of DVT (area under the curve, 0.703, 95 percent confidence interval [CI], 0.572–0.834; p=0.004). This was subsequently confirmed by logistic regression analysis (risk ratio, 3.74, 95 percent CI, 1.27–10; p=0.016).