Abstract: Objective To investigate the value of serum amyloid A4 (SAA4) and suppressor of cytokine signaling 1 (SOCS1) in the early differential diagnosis of spinal tuberculosis (STB) and pyogenic spondylitis (PS). Methods The clinical information from STB patients (STB group, n=62) and PS patients (PS group, n=52) who visited the First Affiliated Hospital of Xinxiang Medical College from January 2019 to June 2021 were collected, and another 50 healthy individuals from examinations clinic in the same period were taken as the control group. Enzyme linked immunosorbent assay (ELISA) was applied to measure the expression of serum SAA4 and SOCS1; Logistic regression was applied to analyze the influencing factors of identifying STB and PS; Receiver operating characteristic (ROC) curve was applied to analyze the differential value of serum SAA4 and SOCS1 for STB and PS. Results Compared with the control group, serum SAA4 level was increased and SOCS1 level decreased in patients from STB and PS groups (P＜0.05), while the level of SAA4 and SOCS1 in the STB group was higher than those in the PS group (P＜0.05); Logistic regression analysis showed that serum SAA4, and SOCS1 were predictive factors for distinguishing STB from PS (P＜0.05); ROC curve results showed that the area under the curve(AUC) of SAA4 and SOCS1 for distinguishing STB and PS separately was 0.833 and 0.872 with sensitivity of 75.8% and 75.8% and specificity as 65.1% and 66.9% respectively. The AUC of the combination of STB and PS was 0.947, with sensitivity and specificity of 88.7% and 78.0% respectively and the AUC identified by the combination of the two was obviously higher than that identified by SAA4 and SOCS1 alone (Z=2.683, 2.015, P＜0.05). Conclusions The serum levels of SAA4 and SOCS1 in STB patients are significantly higher than those in PS patients and both can be used as early differential indicators for STB and PS. Combined measurement can improve the effectiveness of differential diagnosis.

Key words: spinal tuberculosis, pyogenic spondylitis, serum amyloid A4 (SAA4), suppressor of cytokine signaling 1 (SOCS1), differential diagnosis