A study on the effect of annexinⅤpositive microparticles on hypercoagulability in patients with hip fracture / 中华骨科杂志

ABSTRACT

Objective:To study the correlation between hypercoagulant status of patients with hip fracture and the level of microparticles (MPs) in their peripheral blood, and to explore the feasibility of removing MPs to correct hypercoagulant status in patients with hip fracture.Methods:Sixty-five patients from December 2018 to September 2019 with hip fracture were included. There were 24 males and 41 females with the average age of 75.6±9.8 years old (range 58-95 years). Among them, 27patients (43.1%) were femoral neck fracture and38 patients (56.9%) were intertrochanteric fracture.All patients were diagnosed with X-ray and CT. Meanwhile, about 20 healthy people in the physical examination center included as controls in our study. There were 8 males and 12 females with the average age of 72.3±6.5 years old (range 56-81years). 2 ml of anticoagulant whole blood was taken on an empty body in the morning, and purified microparticlesby whole-blood density gradient centrifugation in whole blood were identified by electron microscope and nanoparticle tracking analyzer. After cell free plasma (CFP) was obtained by whole-blood density gradient centrifugation, the number of whole annexin V (AV) positived MPs and these MPs which from platelet (PMPs) was determined by flow cytometry. The activated clotting time (ACT) was determined by coagulation and platelet function analyzer to evaluate the degree of hypercoagulability. Then, Logistic analysis was performed on risk factors associated with hypercoagulability to determine whether the level of MPs was an independent risk factor for hypercoagulability, and the correlation between ACT value and MPs level was analyzed. Finally, the four coagulation items of each sample CFP before and after MPs removal were determined by automatic coagulation analyzer.Results:Under electron microscopy, MPs presented vesicular appearance,with a complete double-layer membrane structure, the size was in the range of 100-1 000 nm, and the morphology was not uniform. there were irregular vesicular and circular vesicular general shapes. The average size of MPs in peripheral blood of patients with hip fractures was 239.7±4.0 nm. The mean size of MPs distribution in the control group was 247.7±3.3 nm, and there was no statistically significant difference in MPs diameter between the two groups. The average level of circulating AV +MPs in patients with hip fracture was 564±171/μl, and the average level of PMPs was 326±104/μl. In the control group, the average level of AV +MPs was 252±82/μl, the average level of PMPs was 192±41/μl, the difference between AV +MPs and PMPs was statistically significant ( P<0.05). The average ACT level of patients with hip fracture was 324±94 s, while the average ACT level of the normal population was 535±76 s, and the difference between the two was statistically significant ( P<0.05). Single factor logistic regression analysis showed that the levels of APTT, PMPs and AV +MPs may be risk factors for hypercoagulability, and multivariate logistic regression analysis showed that AV +MPs is an independent risk factor for hypercoagulability.It has a highly negative correlation with ACT ( r=-0.822, P<0.05). The results of four coagulation items determined by CFP were PT 10.8±0.46 s, APTT 30.6±1.56 s, Fib 3.08±0.36 g/L, INR 0.98±0.04 and TT 19.3±0.62 s. After the removal of MPs, the coagulation function was PT 10.8±0.52 s, APTT 32.4±3.0 s, Fib 2.90±0.33 g/L, INR 0.99±0.05 s, and TT 19.9±0.63 s. There was no statistically significant difference before and after coagulation function. Conclusion:There is a hypercoagulable state in patients with hip fracture, moreover, the level of AV +MPs is an independent risk factor for hypercoagulability, which is highly correlated with ACT, and MPs has no significant effect on the classic four factors of coagulation.