Heparin-Induced Thrombocy topenia Scoring System Could Reduce Complications
Orlando, FL—The heparin-induced throm bocytopenia (HIT) 4T scoring system, developed by G.K. Lo in 2006 and established as a clinical practice guideline by the American Society of Hematology in 2009, could reduce unnecessary use of direct thrombin inhibitor therapy that may result in serious bleeding complications.
The pretest scoring system looks at the degree of thrombocytopenia, timing of platelet fall, thrombosis or other sequelae, and the possibility of other etiologies for thrombocytopenia. Pa tients are then divided into low, intermediate, or high probability of having HIT.
Physicians typically diagnose HIT on clinical grounds—the presence of thrombocytopenia while the patient is taking heparin. A retrospective study applying the 4T system to 100 patients who received direct thrombin inhibitor therapy by Rodina Vatanparast, MD, and colleagues found that a low 4T score correlated 100% with a negative HIT antibody assay.
Of the 100 patients, 73 fell into the low-probability group. Of the low-risk patients, 14 started with a direct thrombin inhibitor, and 10 developed a major bleed requiring blood transfusion support.
“A lot of low-probability-risk patients were started on a direct thrombin inhibitor and had major bleeding complications, yet all of them tested negative,” Dr Vatanparast said. “The patients were empirically treated and, unfortunately, suffered complications as a result. If the physicians had applied the 4T system at the bedside, that might have been prevented.”
Dr Vatanparast has informed the medical staff about the study findings and presented them to hospital administrators, who added using the 4T scoring system to the institution’s core measures when assessing a patient with suspected HIT and then selecting only patients with intermediate-tohigh probability for further therapeutic intervention.
On follow-up, Dr Vatanparast has found physicians are applying 4T more often, and they are being more judicious in starting patients on inhibitor therapy, which has led to a decrease in bleeding complications.
“Education about the intervention has seemed to help,” Dr Vatanparast said.