Relationship between estimated and observed heparin sensitivity indices in cardiac and thoracic aortic surgery

BACKGROUND: Little evidence exists on the relationship between the estimated heparin sensitivity index (HSI) based on commonly available clinical and laboratory data and observed HSI in the adult population. This retrospective study assessed the relationship between the observed and estimated HSIs. METHODS: This study was conducted in an academic, single-institution setting. Patients aged ≥ 20 years who underwent cardiac and thoracic aortic surgery and requiring cardiopulmonary bypass were included. Clinical and laboratory data, including age, sex, and platelet count, were collected. The fibrinogen-albumin ratio index was calculated by dividing the fibrinogen value by the albumin value, multiplied by 10.The HSI was calculated using the formula: (activated clotting time after initial heparin administration—baseline activated clotting time)/initial heparin dose (IU/kg). The estimated HSI was based on the results of multiple regression analysis that included clinically relevant factors. The intraclass correlation coefficient between the observed and estimated HSIs was used to assess. RESULTS: In total, 560 patients with valid activated clotting time (ACT) values after initial heparin administration were included in the final analysis to explore associated factors using the estimated HSI. Multiple regression analysis revealed that hemodialysis, platelet count, fibrinogen-to-albumin ratio index, baseline activated clotting time, and initial heparin dose were significantly associated with the HSI. The mean (standard deviation) observed and estimated HSIs were 1.38 (0.43) and 1.55 (0.13), respectively, with an intra-class correlation coefficient of 0.10. CONCLUSIONS: The correlation between the observed and estimated HSIs was low, and a formula with high accuracy for estimating the HSI is needed. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40981-023-00642-8.