What is the rate of anti PF4 antibody among the patients suspected for HIT referred to special coagulation lab of IBTO

Background:Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction caused by heparin-dependent IgG antibodies that activate platelets and leading to generation of thrombin which is responsible for venous and arterial thrombosis. HIT diagnosis is based on clinical evaluation in association with laboratory method confirmation. 4TScore is a system used for ruling out of HIT based on clinical data. In patients with positive clinical data (score: 4- 8), serologic assessment for antiPF4 Ab and HIT functional assays are necessary for confirmation of diagnosis. Serologic assays like EIA identify formation of Abs against Heparin-PF4 complex. There are several rapidtests like particle gel immunoassay and IgG- specific rapid lateral flow immunoassay (LFIA) for emergency detection of anti PF4 antibodies. Functional assays detect agroup of antiPF4 antibodies with capacity of activating platelets ( SRA and HIPA) that are specific for diagnosis of HIT but require fresh humans platelets and they are time-consuming and no commercial quality control is available. Aim: The aim of this retrospective study is to evaluate the results of a rapid anti-PF4 assay ( LFIA ) which is used for screening of HIT in patients suspected for HIT who have been referred to special coagulation laboratory of IBTO . Method: atients who have been referred to coagulation laboratory of IBTO from March, 2016, through October, 2017, and LFIA (STic Expert_ HIT) test was performed for them were included in this study. The following results were analyzed: age, gender, 4TScore and rapid LFIA result. Also anti-PF4-heparin antibodies ( ELISA) have been performed for 25 of patients that their specimens were availableResults: There were 79 patients included in the study with mean age 64.6±19 years. Overall 46 patients (58%) were male and 33 (12%) were female. 14 patients (21.5%) were LFIA positive .see Algorithm 1.

Keywords:

Heparin Induced Thrombocytopenia , Rapid HIT test , LFIA