Reduced ADAMTS13 activity and thrombocytopenia as predictors of unfavorable outcome in patients with COVID-19 undergoing hemodialysis

Aim. The study aimed to explore the relationship between disturbances in the ADAMTS13/von Willebrand factor (vWF)/platelet system and the risk of mortality in COVID-19 patients ( n =90) with impaired renal function and thrombocytopenia. The retrospective analysis included patients treated between May 2020 and August 2022 at the nephrology department of the 52nd city Hospital in Moscow. Blood counts were assessed upon hospital admission. Results. Median ADAMTS13 activity in discharged patients ( n =62) was 91.0% of normal (95% CI 75.0‑105%), and in deceased patients ( n =26) it was significantly reduced to 74.0% (95% CI 42‑84%; p <0.001). Conversely, vWF antigen level and its activity were significantly elevated in all patients but showed no difference between survivors and non-survivors. Platelet counts were 114×10 3 /μl (95% CI 103 to 128×10 3 /μl) in survivors and 43.0×10 3 /μl (95% CI 25.7 to 59.9×103/μl) in deceased patients ( p <0.001). Platelets counts correlated positively with ADAMTS13 activity (Spearman coefficient rho = 0.514; p <0.001) were independ of vWF level or activity. Among patients undergoing hemodialysis (HD), lower ADAMTS13 activity and platelet counts were significantly associated with mortality. ROC curve analysis revealed that ADAMTS13 ≤79% and ≤53% increased the odds ratio (OR) for mortality in HD patients ( n =58) to 8.53 (95% CI 2.12‑34.3; p =0.0025) and 27.6 (95% CI 3.11‑245; p =0.0029) respectively. A platelet count ≤75×10 3 /μl rised the OR to 10.9 (95% CI 3.00‑39.2; p =0.0003). In HD patients with acute kidney injury superimposed on chronic kidney disease ( n =10), ADAMTS13 activity ≤79% increased the OR for mortalirty to 117 (95% CI 1.9‑7960; p =0.023). In contrast, no significant association between ADAMTS13 activity and mortality was observed in patients not undergoing HD or kidney transplant recipients. Survival probability in COVID-19 patients on HD with ADAMTS13 activity ≤53% was 3.22±0.92 times lower ( p <0.01) after 35 days of hospital admission compared to patients with ADAMTS13 activity >53%. Conclusion. These findings suggest that reduced ADAMTS13 activity and platelet counts are strong predictors of poor outcomes in COVID-19 patients undergoing hemodialysis.