Asymptomatic deep venous thromboses are highly prevalent among prolonged hospitalized severe covid-19 patients despite thromboprophylaxis
Authors: M. Lucijanic, N. Piskac Zivkovic, M. Ivic, M. Sedinic, B. Brkljacic, A. Mutvar, D. Rudan, B. Barsic, I. Luksic, R. Kusec, G. Ivanac
Journal: HemaSphere (2021)

Background: Patients with severe symptoms of COVID-19 often require prolonged hospitalization with reduced mobility due to both imposed restrictions and objective decline in functional status. Aims: Prompted by literature reports of high asymptomatic VTE prevalence in COVID-19 patients and our own clinical experience, we aimed to assess a prevalence of DVT among prolonged hospitalized COVID-19 patients without deep venous thrombosis (DVT) clinical suspicion and to investigate its potential predictors. Methods: During January 2021 we have prospectively undertaken bilateral lower extremity deep veins duplex ultrasound evaluation in 102 consecutive COVID-19 patients without clinical suspicion of DVT that were prolonged hospitalized in our institution. Eligible patients were adult (≥18 years) ward patients that required hospitalization for ≥7 days. Patients who developed clinical suspicion of DVT, unable to cooperate with the ultrasound procedure or were not sufficiently stable to undergo the ultrasound procedure were considered ineligible for the study. All patients received at least prophylactic doses of low molecular weight heparin. Results: Median age was 71.5 years. A total of 54/102 (52.9%) patients were males, 96/102 (94.1%) required oxygen-supplementation therapy. Median length of hospitalization at the time of evaluation was 18 days and median time from the start of COVID-19 symptoms was 27 days. DVT was detected in 26/102 (25.5%) patients without clinical suspicion. Distal DVT was the most common [22 patients (84.6% of the DVT cohort;21.6% of the overall cohort)]. Proximal DVT was present in four patients (16% of the DVT cohort;3.9% of the overall cohort), among them three had popliteal thrombosis and one had femoral thrombosis. Pulmonary embolism (PE) was detected in 17/70 (24.3%) patients who were similarly distributed among patients with and without asymptomatic DVT [5/17 (29.4%) and 12/53 (22.6%);P=0.571]. Patients that were mechanically- ventilated ICU survivors presented with highest frequency of DVT [6/10 (60%)], whereas patients treated with high-flow oxygen therapy and prolonged-hospitalized patients had similar DVT frequency [7/33 (21.2%) and 13/59 (22%), respectively];P=0.031, Figure. D-dimers at the time of hospital admission showed no significant association with the presence of DVT (P=0.280) but there was a statistically significant trend of higher frequency of asymptomatic DVT among patients with higher level of control D-dimers (P=0.034). Patients with and without DVT significantly differed in modified IMPROVE (median 3 and 2 points, respectively;P=0.021) and IMPROVEDD VTE risk-scores (median 4 and 3 points, respectively;P=0.029). Only 17/26 (65.4%) of patients with DVT would fulfill post-discharge thromboprophylaxis criteria (modified-IMPROVE score ≥2 and D-dimers 2x above normal or modified IMPROVE score ≥4 (COVID-19 Treatment Guidelines Panel 2021)). Other variables that were significantly associated with the presence of DVT were known thrombophilia (P=0.015) and higher body temperature on admission (P=0.001). Intensity of thromboprophylaxis, previous anticoagulation, CRP, age, sex, COVID-19 clinical prognostic-scores (MEWS, 4C-mortality score) and Padua VTE risk-score were not significantly associated with the occurrence of DVT (P>0.05 for all analyses). Summary/Conclusion: Systematic ultrasound assessment of prolonged hospitalized severe COVID-19 patients prior to hospital discharge is probably needed, especially of ICU survivors, to timely recognize and appropriately treat patients with asymptomatic DVT.