Heparin thromboprophylaxis is routinely administered during hospitalization for coronavirus disease 2019 (COVID-19). Due to the immune stimulation related to COVID-19, there is ongoing concern regarding a heightened incidence of heparin-induced thrombocytopenia (HIT). We performed a literature search using PubMed, EMBASE, Cochrane and, medRxiv database to identify studies that reported clinical and laboratory characteristics and/or the incidence of HIT in COVID-19 patients. The primary aim was to systematically review the clinical features and outcomes of COVID-19 patients with confirmed HIT. The secondary objective was to perform a meta-analysis to estimate the incidence of HIT in hospitalized COVID-19 patients. A meta-analysis of 7 studies including 5,849 patients revealed the pooled incidence of HIT in COVID-19 of 0.8% (95% confidence interval [CI], 0.2-3.2%; I2 = 89%). The estimated incidences were 1.2% (95%CI, 0.3-3.9%; I2 = 65%) versus 0.1% (95%CI, 0.0-0.4%; I2 = 0%) in therapeutic versus prophylactic heparin subgroups, respectively. The pooled incidences of HIT were higher in critically ill COVID-19 patients (2.2%, 95%CI, 0.6-8.3%; I2 = 72.5%) compared to non-critically ill patients (0.1%, 95%CI, 0.0-0.4%: I2 = 0%). There were 19 cases of confirmed HIT and one with autoimmune HIT for clinical and laboratory characterization. The median time from heparin initiation to HIT diagnosis was 13.5 (interquartile range [IQR], 10.75, 16.25) days. Twelve (63%) developed thromboembolism after heparin therapy. In conclusion, the incidence of HIT in COVID-19 patients was comparable to non-COVID-19 medical patients, with higher incidences with therapeutic anticoagulation and in critically ill patients.

Background and Objectives Due to rebalanced haemostasis in cirrhosis, viscoelastometric testing (VET) is more accurate than standard coagulation tests (SCTs) in preprocedural haemostatic evaluation, resulting in decreased unnecessary transfusion. We aimed to determine the impact of VET‐guided strategy on postprocedural bleeding, periprocedural transfusion rates and quantities, transfusion‐related adverse events (TRAEs), lengths of stay (LOS) and mortality from randomized controlled trials (RCTs) of cirrhotic patients. Methods PubMed and EMBASE were searched for RCTs comparing VET‐guided with SCT‐guided transfusion in cirrhotic adults undergoing esophagogastroduodenoscopy, liver transplantation or other invasive interventions. Using random‐effects models, the pooled risk ratios (RRs) and/or mean differences (MDs) of postprocedural bleeding‐free events and the other outcomes were estimated alongside 95% confidence intervals (CIs). Results Of seven included RCTs (n = 421; 72.2% men; mean age 49.1 years), VET‐guided transfusion did not change postprocedural bleeding‐free statuses (RR 1.05; 95% CI 0.94–1.17). However, VET‐based algorithms decreased the rates of fresh frozen plasma (FFP; RR 0.52; 95% CI 0.35–0.77) and platelet transfusions (RR 0.34; 95% CI 0.16–0.73), the quantities of transfused FFP (MD −1.39 units; 95% CI −2.18 to −0.60), platelets (MD −1.06 units; 95% CI −2.01 to −0.12) and cryoprecipitate (MD −7.13 units; 95% CI −14.20 to −0.07) and the risk of TRAEs (RR 0.42; 95% CI 0.27–0.65). The overall mortality rates and LOS were not significantly different between two groups. Conclusion Compared with conventional SCT‐guided, VET‐guided strategy decreases periprocedural plasma and platelet transfusions and TRAEs, without increasing haemorrhagic complications, LOS or mortality in cirrhosis.