Expression of programmed death receptor-1 and its prediction of postoperative infectious complications in elderly patients with hip fracture

Abstract

Objective To investigate the expression of programmed death receptor-1 (PD-1) and its value in predicting the infectious complications in elderly patients with hip fracture. Methods A total of 119 elderly patients with intertrochanteric fracture(observation group) were prospectively enrolled for this study from August 2015 to August 2016 at Department of Orthopaedics, The Seventh Medical Center of PLA. They were 86 males and 33 females with an age of 80.7±8.1 years. Another 20 elderly out-patients with gonarthritis but without trauma or major medical disease were enrolled as a control group. The observation group received closed reduction and internal fixation with proximal femoral intramedullary nails. The PD-1 expression in peripheral blood T cells was detected at preoperation, 1, 3 and 5 days postoperation in the patients of observation group. They were further divided into an infection group and a non-infection group depending on whether infectious complications occurred during the follow-up period. The association between PD-1 and infectious complications was analyzed and its predictive value was calculated. Results The observation group and the control group, as well as the infection group and the non-infection group, were compatible due to their insignificant differences in baseline data(P>0.05).Compared with the control group, the expression of PD-1 in the peripheral blood T cells in the observation group was all significantly increased at preoperation, 1, 3 and 5 days postoperation (P<0.05). The PD-1 expression in patients of the infection group (24 cases) increased significantly higher at 1, 3 and 5 days postoperation (33.60%±2.44%, 35.68%±4.05% and 30.36%±4.42%) than in those of the non-infection group (29.57%±3.20%, 21.45%±2.20% and 20.94%±2.30%) (P<0.05). The PD-1 expression in the infection group reached its peak at 3 days postoperation and did not fall to the preoperative level at 5 days postoperation. However, the PD-1 expression in patients of the non-infection group (95 cases) showed a transient rise only on the first day postoperation. The cutoff value of the difference in PD-1 expression between 1 and 3 days postoperation that could predict the infectious complications was 3.4%, with a sensitivity of 95.6% and a specificity of 92.6%. Conclusions The expression of PD-1 may significantly increase after intramedullary fixation of hip fracture in elderly patients. The patients with infectious complications may exhibit a greater and longer increase in PD-1 expression than those without infectious complications. The difference in PD-1 expression between 1 and 3 days postoperation has a good predictive value for infectious complications because its high sensitivity and specificity. Key words: Hip fractures; Infections; Complications; Programmed death receptor-1