ObjectiveTo discuss the correlation of the surgical risk score with the change of T cell subsets and the occurrence of postoperative complications. MethodsA total of 260 patients with hip fractures treated in our department were enrolled in this study and divided into high-risk group ( Group A) and low-risk group (Group B) based on the surgical risk score. The fasting peripheral venous blood was taken in the morning at one day before surgery and at days 1,3, 5, 7 and 14 after surgery for measuring CD3, CD4 and CD8 levels respectively in two groups.In the meantime, the correlation of level changes with risk score and postoperative complications was observed in two groups. ResultsThere were two patients with lung infection in the Group B, with no death. There were two patients with pulmonary infection, one with wound infection and two with deep vein thrombosis, with one death. The postoperative levels of CD3 and CD4 in the Group A and Group B were significantly lower than those in the control group (P ＜ 0.01 ), which reached the lowest level at day 1 after operation and recovered to normal at day 5 after operation. The postoperative levels of CD3 and CD4 in the Group A recovered near to normal at day 7 and to normal at day 14. While the postoperative levels of CD3 and CD4 in the Group B remained low level even at day 14. The level of CD8 decreased at days 1 and 5 in the Group A, then increased and remained relatively stable, while the level of CD8 increased in the Group B. The T cell subsets in both groups recovered from low to high trend at days 1-7 after surgery. The higher preoperative score had more obvious decrease and slower recovery of the T cell subsets. ConclusionsSurgical risk score has positive correlation with the change of T cell subsets and postoperative complications, which can more accurately predict the postoperative outcome of the old patients.