Heparin Induced Thrombocytopenia (HIT) is a serious complication from administration of heparin products. The 4T score is a validated pre-test probability tool to screen for HIT in hospitalized patients. As the negative predictive value (NPV) is very high further testing for HIT in patients with a low score can be avoided. Our objective was to determine trends at our hospital with respect to utilization of HIT antibody (HITAb) testing and evaluate economic burden from unnecessary HIT testing. A retrospective cohort review was performed on patients age 18 and above admitted to a tertiary care center from February 2013 to December 2014 who underwent HITAb testing. Surgical ICU patients were excluded. Patients were stratified into low, intermediate, and high risk for HIT based on the 4T model. Statistical analysis was performed using Chi square and regression models. Of 150 patients that underwent HITAb testing, 134 met inclusion criteria. 73 were male (54.47 %) and mean age was 55.50 ± 17.27 years. 81 patients had a low 4T score 0-3. Analysis of testing trends showed 60.44 % of patients were tested for HITAb despite being low risk using the 4T model. Only three patients with low 4T score were positive on confirmatory SRA testing (NPV 96.29 % CI 95 = 89.56-99.23 %). Expenditure due to inappropriate testing and treatment was estimated at $103,348.13. The majority of HITAb testing was found unnecessary based on the investigator calculated 4T score. We propose implementation of an electronic medical record (EMR) based calculator in order to reduce unneeded tests and reduce use of costlier alternative anticoagulants.
Keywords: 4T score; Antibody; Anticoagulation; Cost-effective; Heparin; Heparin induced thrombocytopenia; Thrombosis.