Raymond Smith, PharmD
New Hanover Regional Medical Center
Wrightsville Beach, North Carolina
Disclosure information not submitted.
Lindsey Tincher, BCCCP, PharmD
New Hanover Regional Medical Center, North Carolina
Disclosure information not submitted.
Zackery Bullard, BCCCP, BCPS, PharmD
Clinical Pharmacist
New Hanover Regional Medical Center, United States
Disclosure information not submitted.
Title: Appropriateness of Heparin-PF4 Antibody Testing in Cardiology and Cardiac Surgery ICU Patients
Introduction:
Heparin-Induced thrombocytopenia (HIT) is a severe adverse drug reaction that requires immediate action to prevent complications. The ASH recommends using the “4 T’s Score” to estimate the probability of HIT. If the 4 T’s score reflects an increased probability of HIT (score ≥4), the guidelines recommend laboratory testing for heparin antibodies with confirmatory serotonin release assay, discontinuation of heparin products and initiation of a non-heparin anticoagulant. An alternative pre-test probability score known as CPB was developed for determining probability of HIT in patients after CABG surgery. Our study aims to assess if heparin antibody testing is being performed in accordance with current guideline recommendations.
Methods:
This is a single-center retrospective chart review conducted from January 1, 2017 to January 1, 2020. Patients were included if they were ≥18 years old, admitted by the cardiac ICU or cardiac surgery service and had heparin-PF4 antibody tests ordered. We collected demographics data, heparin-PF4 and SRA results, platelet trends, mechanical support devices utilized, and cardiopulmonary bypass data to retrospectively calculate 4 T’s scores and CPB scores for all applicable patients and determine if laboratory tests were sent appropriately. Additionally, we collected data on alternate anticoagulant use during suspected HIT.
Results:
We observed that 78.7% of patients underwent cardiopulmonary bypass, and 45.4% of patients had cardiac devices present. Heparin-PF4 tests were positive in 27 (25%) patients, and HIT was confirmed with a positive SRA in 10 (9.3%) patients. Based on calculated 4 T’s scores, 21 (19.4%) tests were sent appropriately based on current guideline recommendations. We also observed that 80% of patients with confirmed HIT had a 4 T’s score ≥4. According to retrospectively calculated CPB scores, 68.2% of heparin-PF4 tests were sent in accordance with guidelines, and 100% of patients with confirmed HIT had a CPB score ≥2. When HIT was suspected, heparin was stopped in 55.6% of patients, and alternate anticoagulation was given to 25% of these patients.
Conclusion:
We found that 81.6% of heparin antibody tests were sent inappropriately based on 4 T’s scores and 31.8% of heparin antibody tests were sent inappropriately based on CPB scores.