RESUMO
Objective To investigate the level of coagulation factor Ⅺ(FⅪ)in patients with venous thrombosis of lower limbs and its correlation with recurrence risk.Methods A total of 220 pa-tients with deep vein thrombosis(DVT)admitted in our hospital from February 2018 to February 2019 were enrolled as the study group,and another 50 healthy individuals taking physical exami-nation during same period served as the control group.After a 3 years followed,the study group ultimately included 197 cases,according to the results of restricted cubic spline(RCS),the study group was divided into low(FⅪ＜10.3 U/L,94 cases),medium-(10.3-12.1 U/L,52 cases)and high-level groups(＞12.1 U/L,51 cases).The plasma level of FⅪ was detected in the study group 1 month after the end of anticoagulant therapy,and the results were compared with those of the control group during physical examination.Cox model was used to analyze the influence of FⅪ on the recurrence of DVT,and RCS was employed to analyze the relationship between DVT recur-rence and FⅪ level.Kaplan-Meier curve was plotted to analyze the recurrence risk of DVT with different FⅪ levels.The patients from the study group were followed up for 3 years.Results The FⅪ level was significantly higher in the study group than the control group(P＜0.05).During fol-low-up period,33 patients(16.75％)had DVT recurrence.The Cox model analysis after adjust-ment of sex and age showed that FⅪ level was a risk factor for DVT recurrence(P＜0.05).When the FⅪ level was set into tertile and the risk ratio was calculated after adjustment,FⅪ＜10.3 U/L,and the average FⅪ level at this stage was 9.2 U/L,the risk ratio was 0.82(95％CI:0.673-0.984);Patients with FⅪ between 10.3 and 12.1 U/L,and the average FⅪ at this stage was 11.4 U/L,the risk ratio of 1.04(95％CI:0.813-1.432).The those with FⅪ＞12.1 U/L,and the average FⅪ at this stage was 13.8 U/L,hazard ratio of 1.38(95％CI:0.921-1.563).Kaplan-Meier curve analysis showed that the recurrence risk was 28.62％(95％CI:25.633-31.609),30.10％(95％CI:27.594-32.606)and 38.06％(95％CI:34.306-41.371),respectively for the low-,medium-,and high-level groups,with significant correlation among the three groups(x2=6.631,P=0.036).Conclusion Compared with healthy individuals,plasma FⅪ level is at a high level in the DVT patients.With the increment of FⅪ level,the risk of DVT recurrence increases.Two FⅪ levels,10.3 U/L and 12.1 U/L,can be used as reference points for the obvious increase of DVT recur-rence rate.