Prospective evaluation of a rapid nanoparticle-based lateral flow immunoassay (STic Expert (R) HIT) for the diagnosis of heparin-induced thrombocytopenia

A rapid lateral flow immunoassay (LFIA) (STic Expert (R) HIT), recently developed for the diagnosis of heparin-induced thrombocytopenia (HIT), was evaluated in a prospective multicentre cohort of 334 consecutive patients. The risk of HIT was estimated by the 4Ts score as low, intermediate and high in 28.7%, 61.7% and 9.6% of patients, respectively. Definite HIT was diagnosed in 40 patients (12.0%) with positive results on both enzyme-linked immunosorbent assay (Asserachrom (R) HPIA IgG) and serotonin release assay. The inter-reader reproducibility of results obtained was excellent (kappa ratio > 0.9). The negative predictive value of LFIA with plasma samples was 99.6% with a negative likelihood ratio (LR) of 0.03, and was comparable to those of the particle gel immunoassay (H/PF4-PaGIA (R)) performed in 124 cases. Positive predictive value and positive LR were 44.4% and 5.87, respectively, and the results were similar for serum samples. The probability of HIT in intermediate risk patients decreased from 11.2% to 0.4% when the LFIA result was negative and increased to 42.5% when it was positive. In conclusion, the STic Expert (R) HIT combined with the 4Ts score is a reliable tool to rule out the diagnosis of HIT.