Combination of 4Ts score and PF4/H-PaGIA for diagnosis and management of heparin-induced thrombocytopenia: prospective cohort study.
Blood. 2015 Apr 29;
Authors: Linkins LA, Bates SM, Lee AY, Heddle NM, Wang G, Warkentin TE
Abstract
Rapid exclusion of heparin-induced thrombocytopenia (HIT) is needed to determine which patients can continue to receive heparin. In this prospective management study, 526 participants had a 4Ts score, rapid immunoassay (PF4/H-PaGIA) and serotonin-release assay (SRA) performed. While awaiting SRA results, participants with low 4Ts score (irrespective of PF4/H-PaGIA result) or intermediate 4Ts score plus a negative PF4/H-PaGIA result received prophylactic doses of danaparoid or fondaparinux; all others received therapeutic doses of nonheparin anticoagulants. The primary outcome was the frequency of management failures defined as HIT positive participants with a low 4Ts score (irrespective of PF4/H-PaGIA result) or intermediate 4Ts score plus negative PF4/H-PaGIA result. Six participants (1.1%; 95%CI,0.2-2.1%) were management failures. A negative PF4/H-PaGIA result reduced the pretest probability of HIT from 1.9% to 0% (95%CI, 0-1.3%), 6.7% to 0% (95%CI, 0-2.7%) and 36.6% to 0% (95%CI, 0-14.3%) in the low, intermediate and high score groups, respectively. A positive PF4/H-PaGIA increased the probability of HIT in the low score group to 15.4% (95%CI, 5.9-30.5). Thus, a low or intermediate 4Ts score plus negative PaGIA excluded HIT, whereas any other combination of results justified use of alternative anticoagulants until HIT could be excluded. This trial was registered at www.clinicaltrials.gov #NCT00489437.
PMID: 25926600 [PubMed - as supplied by publisher]