Prospective comparison of the HEP score and 4Ts score for the diagnosis of heparin-induced thrombocytopenia

Abstract

The HIT Expert Probability (HEP) score compared favorably with the 4Ts score in a retrospective study. We assessed the diagnostic accuracy of the HEP score compared with the 4Ts score in a prospective cohort of 310 patients with suspected heparin-induced thrombocytopenia (HIT). A member of the clinical team calculated the HEP score and 4Ts score. An independent panel adjudicated HIT status based on a clinical summary as well as the results of HIT laboratory testing. The prevalence of HIT in the study population was 14.7%. At a cutoff of ≥3, the HEP score was 95.3% sensitive (95% confidence interval [CI], 84.2-99.4) and 35.7% specific (95% CI, 29.8-42.0) for HIT. A 4Ts score of ≥4 had a sensitivity of 97.7% (95% CI, 86.2-99.8) and specificity of 32.9% (95% CI, 27.2-39.1). The areas under the receiver operating characteristic (ROC) curves (AUCs) for the HEP score and 4Ts score were similar (0.81 [95% CI, 0.74-0.87] vs 0.76 [95% CI, 0.69-0.83]; P = .12). The HEP score exhibited a significantly higher AUC than the 4Ts score in patients in the intensive care unit (ICU) (0.86 vs 0.79; P = .03). Among trainee scorers, the HEP score performed significantly better than the 4Ts score (AUC, 0.80 vs 0.73; P = .03). Our data suggest that either the 4Ts score or the HEP score may be used in clinical practice. The HEP score may be preferable in ICU patients and among less experienced clinicians.

The risk of major bleeding in patients with suspected heparin‐induced thrombocytopenia

“…Whereas many previous studies have relied solely on laboratory testing or 4Ts score to define HIT, our use of a rigorous adjudication process to define HIT status was implemented to reduce the potential for misclassification. The study population was drawn from a prospective evaluation of clinical prediction scores for HIT . All participants had prospectively calculated 4Ts scores and were contacted to obtain 30‐day outcomes.…”

“…The study population was drawn from a prospective comparison of the HEP score and 4Ts score . Details regarding eligibility and enrollment have been previously described .…”

“…Clinical case summaries of the remaining subjects were prepared using a standardized case report form to include detailed clinical information about the hospital course, the platelet count trend, exposure to heparin and other medications, thrombotic events, the results of the HIT antibody ELISA and SRA, and 30‐day follow‐up information. An independent adjudication panel of three experts in HIT (GA, MC, LR) reviewed the clinical case summaries and determined if patients were positive for HIT or negative for HIT as previously described . HIT‐positive status was defined as the consensus opinion of the adjudication panel.…”

“…16 Details regarding eligibility and enrollment have been previously described. 16 In brief, 310 patients hospitalized at the Hospital of the University of Pennsylvania or an affiliated community hospital were enrolled from June 2012 to January 2015. All patients in the study were suspected of having acute HIT, prompting the clinical care team to order laboratory testing for HIT.…”

“…2 Thus, clinical prediction scores such as the 4Ts score or HIT Expert Probability (HEP) score are useful for estimating the pre-test likelihood of HIT and guiding initial management decisions. 3,16 With an intermediate or high score, clinical practice guidelines recommend stopping heparin and starting an alternative anticoagulant while awaiting confirmatory laboratory test results. 4,5 The choice to treat patients empirically for HIT is a high-stakes decision.…”