Evaluation of a clinical scoring scale to direct early appropriate therapy in heparin-induced thrombocytopenia.
BACKGROUND
Heparin-induced thrombocytopenia (HIT) is a serious adverse effect associated with heparin therapy. Current laboratory confirmation for immune mediated HIT often results in false positives and unnecessary treatment, exposing individuals to possible complications. As a result, clinical evaluation has been recommended in conjunction with laboratory testing. We hypothesize that utilization of a clinical scoring scale, the 4T's, will result in the initial appropriate therapy for suspected HIT.


METHODS
This is a retrospective chart review of 108 patients who underwent ELISA testing for HIT at a university hospital. The 4T's scale was applied, stratifying individuals into low, intermediate, and high-risk categories. Each risk score was compared to the ELISA results to determine if the 4T's can predict the diagnosis of HIT and result in appropriate management. ELISA optical density scores as well as incidence of adverse events were also compared among risk categories.


RESULTS
Individuals with low risk correlate with a negative ELISA compared to intermediate and high-risk individuals (p = 0.01 and p<0.01) and also were significantly more likely to predict institution of appropriate therapy (p<0.01). Median optical density scores were 0.184 (0.046-2.116), 0.226 (0.067-1.887), and 0.476 (0.096-1.309) for low, intermediate, and high 4T scores. Major adverse events include thrombosis and bleeding.


CONCLUSIONS
Individuals with low risk were more likely to receive initial, appropriate therapy and were also significantly more likely to have a negative ELISA test result. Individuals with low risk determined by the 4T score therefore may have therapy and serologic testing for HIT withheld.
Wirth
Scott M
SM
UK HealthCare, University of Kentucky; Lexington, Kentucky, USA. smwirt2@email.uky.edu
Macaulay
Tracy E
TE
Armitstead
John A
JA
Steinke
Douglas T
DT
Blechner
Michael D
MD
Lewis
Daniel A
DA
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects*; D001780:Blood Coagulation Tests; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D010979:Platelet Function Tests; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000175:diagnosis* / Q000188:drug therapy
D000925:Anticoagulants; D005343:Fibrinolytic Agents; D010975:Platelet Aggregation Inhibitors; D006493:Heparin