Heparin-induced thrombocytopenia: reducing misdiagnosis via collaboration between an inpatient anticoagulation pharmacy service and hospital reference laboratory

Misdiagnosis of heparin-induced thrombocytopenia (HIT) is common and exposes patients to high-risk therapies and potentially serious adverse events. The primary objective of this study was to evaluate the impact of collaboration between an inpatient pharmacy-driven anticoagulation management service (AMS) and hospital reference laboratory to reduce inappropriate HIT antibody testing via pharmacist intervention and use of the 4T pre-test probability score. Secondary objectives included clinical outcomes and cost-savings realized through reduced laboratory testing and decreased unnecessary treatment of HIT. This was a single center, pre-post, observational study. The hospital reference laboratory contacted the AMS when they received a blood sample for an enzyme-linked immunosorbent HIT antibody (HIT Ab). Trained pharmacists prospectively scored each HIT Ab ordered by using the 4T score with subsequent communication to physicians recommending for or against processing and reporting of lab results. Utilizing retrospective chart review and a database for all patients with a HIT Ab ordered during the study period, we compared the incidence of HIT Ab testing before and after implementation of the pharmacy-driven 4T score intervention. Our intervention significantly reduced the number of inappropriate HIT Ab tests processed (176 vs. 63, p < 0.0001), with no increase in thrombotic or hemorrhagic events. Overall incidence of suspected and confirmed HIT was <3 and <0.005 %, respectively. Overall cost savings were $75,754 (US) or 62 % per patient exposed to heparin between the pre and post intervention groups. Collaboration between inpatient pharmacy AMS and hospital reference laboratories can result in reduction of misdiagnosis of HIT and significant cost savings with similar safety.