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Maximum 24‐hour platelet count fall: Metric for improving the diagnosis of heparin‐induced thrombocytopenia among patients with intermediate probability 4Ts scores
Author(s) -
Lefler Daniel S.,
Cuker Adam,
Linkins LoriAnn,
Warkentin Theodore E.,
Pishko Allyson M.
Publication year - 2020
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/jth.14897
Subject(s) - cohort , medicine , heparin induced thrombocytopenia , receiver operating characteristic , metric (unit) , confidence interval , platelet , anticoagulant , cohort study , surgery , operations management , economics
Background Most patients with suspected heparin‐induced thrombocytopenia (HIT) and an intermediate probability 4Ts score do not have HIT. We aimed to develop a metric based on the rate of platelet count fall to aid in discriminating HIT status among patients with an intermediate 4Ts score. Methods We derived a measure of the maximum 24‐hour percentage decrease in platelet count (Fall max ) in a cohort of patients with suspected HIT and an intermediate 4Ts score at the University of Pennsylvania. We validated this metric in a prospectively collected cohort of patients with suspected HIT and an intermediate 4Ts score from four hospitals in Hamilton, Ontario. Results One hundred fifty‐eight and 139 patients were included in the analysis from the derivation and validation cohorts, respectively. Fall max was significantly higher in HIT‐positive patients in the derivation cohort (49.6% versus 38.6%, P = .009) and validation cohort (43.5% versus 29.3%, P = .027). The area under the receiver operating characteristic curve was 0.68 (95% confidence interval [CI] 0.57‐0.78) and 0.71 (0.59‐0.83) in the two cohorts, respectively. At Fall max ≥ 30%, sensitivity and specificity were 95.5% and 29.4% in the derivation cohort and 80.0% and 52.7% in the validation cohort. Conclusions Among patients with suspected HIT and an intermediate 4Ts score, Fall max aided in discriminating HIT‐negative from HIT‐positive patients. Using a measure that accounts for the rate of platelet count fall may help to avoid unnecessary suspension of heparin and treatment with an alternative anticoagulant in HIT‐negative patients with an intermediate probability 4Ts score, though further evaluation is warranted.