Utility of the 4Ts score in excluding heparin-induced thrombocytopenia in lung transplant recipients

Heparin-induced thrombocytopenia (HIT) is a prothrombotic complication following heparin exposure. Data is limited on the incidence of HIT and validity of 4Ts score in the solid organ transplant population. This retrospective observational cohort included patients who underwent lung transplant between August 2015 and June 2018 and had a clinical suspicion of HIT with heparin-PF4 testing. The 4Ts score was correlated with the heparin-PF4 antibody and serotonin release assay (SRA) results, with positive SRA considered confirmed HIT. Of 146 patients evaluated, the overall incidence of HIT was low (2(1%)). Fifty-one patients had heparin-PF4 testing and were included in the cohort; 5 (10%) had positive heparin-PF4 and 1 (2%) had confirmed HIT. The median 4Ts score was 3 (3-4). Thirty (59%), 17 (33%), and 4 (8%) patients had low, intermediate, and high risk, respectively. The intermediate/high risk group compared to the low risk group had a higher use of alternative non-heparin anticoagulation [13 (62%) vs 7 (23%);p = 0.0086)] and a higher incidence of thrombosis [13 (62%) vs 1 (3%);p < 0.0001]. No patient with a low 4Ts score had confirmed HIT, supporting the utility of low 4Ts score to exclude HIT diagnosis in lung transplant recipients.