Pharmacist involvement in clinical assessment and laboratory testing for heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a rare adverse drug reaction. The anti-PF4 antibody assay (ELISA) is utilized to assist in the clinical evaluation of HIT due to its high negative predictability and wide-spread availability. However, it also associated with false positive results. The 4T score can assist in predicting an individual's risk for HIT and the need for further laboratory testing. This was a single-center prospective observational cohort study. Orders for HIT testing were sent via page to a clinical pharmacist to calculate a 4T score. If low risk, the pharmacist contacted the ordering prescriber to recommend discontinuation of laboratory testing. During the study, a clinical support tool was implemented to assist prescribers with ordering HIT tests. The study was divided into a pharmacist intervention group and a control group. A total of 303 pages were received. One hundred nine were missed due to unavailability of the pharmacist at time of page. A pharmacist reviewed 194 pages and intervened on 132. One hundred seven were scored as low risk, 70 as intermediate risk and 9 as high risk. Pharmacist intervention resulted in discontinuing 64 ELISA and 11 serotonin release assay tests. The clinical support tool resulted in a yearly decrease of HIT testing by 27%. Laboratory cost savings totaled $11,000 but did not include avoidance of laboratory technician or drug cost. Pharmacist involvement in the clinical assessment of HIT and the use of a support tool resulted in the reduction of HIT tests in low risk patients.