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

A rapid lateral flow immunoassay (LFIA) (STic Expert^® 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^® 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^®) 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^® HIT combined with the 4Ts score is a reliable tool to rule out the diagnosis of HIT.