A-152 Establishment of reference interval for four coagulation parameters using indirect methods in Chinese population at high-altitude area: a retrospective real-world analysis

Abstract Background The hypoxia state in Tibetan residing in high-altitude regions potentially induce alterations in the coagulation system. The coagulation parameters, including activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), and fibrinogen (FIB), are indicative of the intricate and dynamic interactions among platelets, plasma, and vascular endothelial tissue. Indirect methods were used to establish reference intervals (RIs) for four coagulation parameters based on big data from the adult population of Tibet, a high-altitude area in Western China. Methods Coagulation test data, including APTT, PT, TT, and FIB, collected from health examination population of the People*s Hospital of Tibet Autonomous Region between 2019 and 2023 were collected and cleaned. The Stago STA-R Evolution automatic hemostasis testing analyzer (Diagnostica Stago, Asnières sur Seine, France) and its corresponding analytical reagents were utilized. Coagulation test data were subjected to Box-Cox transformation for normalization and Tukey method for outlier removal. Quantile regression was employed to assess the effect of gender and age. The RIs were calculated using Hoffmann and refineR methods, respectively. Results A total of 5086, 5282, 5386, and 5377 test results for APTT, PT, TT, and FIB were included. Quantile regression analysis revealed significant gender-related effects on all four coagulation parameters (p<0.001). The Hoffmann and refineR method yielded the following total RIs: APTT 30.54–46.32 s and 30.14–44.30 s; PT 10.54–14.51 s and 10.32–13.89 s; TT 14.92–19.46 s and 14.88–18.93 s; FIB 2.05–4.68 g/L and 2.02–4.40 g/L, respectively. Gender-partitioned RIs were further calculated for all four parameters, while age-partitioned RIs were specifically calculated for PT and FIB based on bias ratio values. The lower limits of RIs estimated by the two methods remained consistent, however there was heterogeneity observed in the upper limits. The established RIs for APTT and FIB were significantly higher than those utilized in the plain area and those provided by the manufacturer, whereas the established RIs of TT were significantly lower. Conclusion The RIs for coagulation parameters in the population lived on the Tibetan Plateau exhibited significant divergence from those utilized in the plain area. We advocate for the establishment of specific RIs tailored to high-altitude regions to accurately evaluate the presence of coagulation disorders.