Limitations of a platelet count-based clinical decision support system to facilitate diagnosis of heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a rare complication of heparin exposure with potential for significant morbidity and mortality. Early identification and treatment can prevent catastrophic thrombosis. Herein, we report the performance of a platelet count-based clinical decision support system (CDSS) where providers received a notification when a patient had a platelet count decline of ≥50 %. In the 90-day study period, the CDSS sent 302 notifications on 270 patients. Notifications were frequently inappropriate; 25 % had an expected platelet count decline (organ donation, stem cell transplant), an inaccurate count, or no heparin exposure. Patient testing for HIT prompted by the CDSS was not in accordance with best practice guidelines in most circumstances. For example, 36 % had a low probability 4Ts score, while 42 % with an intermediate or high probability 4Ts score were not tested. Due to concern for lack of efficacy, the CDSS was discontinued. Analysis of an 8-month period before and after discontinuation showed a significant decrease in the number of enzyme immunoassays ordered (547 vs. 386) without a change in the number of patients with HIT identified (13 vs. 13) or the rate of thrombosis in those with confirmed HIT (62 % vs. 62 %). In conclusion, a CDSS based on platelet count decline contributed to "alert fatigue" via inappropriate notification and did not improve evidence-based HIT testing. In addition, its removal did not decrease or delay HIT identification. Additional efforts are needed to better define how CDSS can support the rapid diagnosis and appropriate treatment of patients with HIT.