Applied Value Of IL-22 In Differential Diagnosis Of Fever Of Unknown Origin

Objective This study aims to explore the applied value of IL-22 in differential diagnosis of fever of unknown origin,and to analyze the correlation between IL-22 and other inflammatory indexes.Methods A total of 546 fever patients were enrolled from February 2016 to November 2018.The bacterial group(62 cases),the tuberculosis group(27 cases),and the NIID group(31 cases)were set up based on the clinical and laboratory findings.Patients with bacterial infections was divided into 27 cases of severe infection group and 35 cases of uncomplicated infection group based on the quick Sequential Organ Failure Assessment(q SOFA)and blood culture.We compared the IL-22 and other laboratory data between the groups.The ROC curve was used to calculate the cutoff value of IL-22 in differentiating tuberculosis,and IL-22 was used to assist Quanti FERON TB-Gold Test(QFT)in the diagnosis of tuberculosis.Spearman's rank correlation was used to analyze the correlation between IL-22 and other inflammatory indexes.Results The serum level of IL-22 was significantly lower in tuberculosis group(36.74�18.68pg/ml)than in bacterial group(80.87�60.31pg/ml)or NIID group(98.31�53.91pg/ml).There was no significant difference in IL-22 between the bacterial group and the NIID group(P > 0.05).The cutoff value of IL-22 to distinguish tuberculosis infection was 40pg/ml,the area under the ROC curve(AUC)was 0.798(95%CI,0.681-0.915),the sensitivity and specificity were 78%,66.7%.The sensitivity and specificity of IL-22 combined with QFT for tuberculosis diagnosis were 81.5% and 72.5%.In bacterial infection patients,serum IL-22 level was predominantly higher in severe infection group(130.80�73.26pg/ml)than in uncomplicated infection group(58.60�37.42pg/ml).IL-22 was positively correlated with IL-6(r=0.552,P<0.001),N%(r=0.380,P<0.001),WBC(r=0.310,P<0.001)and CRP(r=0.374,P<0.001),but had no significant correlations with ESR,LDH,PCT,and SF(P>0.05).Conclusions These data suggested that IL-22 is expected to be used for clinical identification of tuberculosis,and evaluating the severity of bacterial infections in FUO.