PO10 | Clinical and laboratory features of long-Covid syndrome: a cross-sectional study of 1,337 Covid-19 survivors

C. Ambaglio¹, S. V. Benatti², C. J. Tartari^1,3, L. Russo^1,3, S. Bolognini^1,3, C. Ticozzi¹, F. Schieppati¹, V. Brusegan¹, S. Venturelli², L. Barcella¹, M. Rizzi², M. Marchetti^1,3, A. Falanga^1,3 | ¹Department of Immunohematology and Transfusion Medicine, Papa Giovanni XXIII Hospital, Bergamo; ²Division of Infectious Diseases, Papa Giovanni XXIII Hospital, Bergamo; ³Department of Medicine and Surgery, University of Milan Bicocca, Monza, Italy

Background: The term ‘long-Covid’ is used to describe in Covid-19 survivors the persistence of symptoms beyond 4 weeks and includes ‘ongoing symptomatic’ (4-12 weeks) and ‘post-Covid-19’ syndrome (>12 weeks) phases, based on symptoms’ duration. Aim: To evaluate the contribution of circulating hemostatic biomarker alterations to the diagnosis of long-Covid syndrome.

Methods: A clinical and diagnostic multidisciplinary follow-up of Covid-19 patients discharged from our Institution after the first pandemic wave was implemented (ACCORDI Study, July – November 2020). In 1310 out of 1337 Covid-19 survivors who attended the clinical visit, blood samples were obtained for measurements of blood cell count, liver and renal function tests, LDH, C-reactive protein, fibrinogen, prothrombin fragment 1+2, D-dimer, von Willebrand factor antigen, thrombomodulin (TM), tissue plasminogen activator and its inhibitor PAI-1.

Results: In the 1337 survivor cohort (863M/474F, median age 60 years, median time from Covid-19 onset=127 days), clinical symptoms were: cardiopulmonary in 50% of subjects, flu-like in 35%, respiratory in 27%, and neurological in 11%. The long-Covid syndrome was diagnosed in 655 patients (375M/280F): 101 classified as ‘ongoing symptomatic’ and 554 as ‘post-Covid’. Among study population, 56 survivors experienced VTE during the acute phase (43M/13F, median age 62 years). 80% had isolated pulmonary embolism; 16% isolated proximal deep vein thrombosis; 4% deep vein thrombosis and pulmonary embolism. A significant association appeared between VTE during acute phase and development of long-Covid syndrome. The hemostatic laboratory analysis of 1310 samples showed no significant differences in the biomarkers’ levels between long-COVID and symptom-free survivors. However, among subjects assessed within 12 weeks from disease onset, the ‘ongoing symptomatic’ group showed significantly higher TM levels (p<0.05) compared with the symptom-free group. Further, after logistic regression analysis corrected for age and gender, TM or PAI-1 levels above the 75th percentile were found significantly associated with a diagnosis of long-Covid (OR 2.156; 95% CI:1.24-3.75; p=0.007).

Conclusions: Our study shows the occurrence of an endotheliopathy in ongoing symptomatic long-Covid patients and supports the role of VTE in the long-Covid syndrome appearance.