Value Of Tuberculosis T-cell Spot Test In Differential Diagnosis Of Ileocecal Lesions

Objective: The paper retrospective analyzed the clinical data of patients with ileocecal lesions,and further explored the clinical value of tuberculosis T-cell spot test(T-SPOT.TB)in the differential diagnosis of ileocecal lesions by comparing T-SPOT.TB with tuberculin skin test(TST)and tuberculosis antibody test about the advantages in diagnosis of intestinal tuberculosis(ITB).Methods: From January 2017 to November 2019,the clinical data of inpatients with ileocecal lesions detected by endoscopy and T-SPOT.TB,TST and TB antibody detection were collected from the Department of Gastroenterology,the First Affiliated Hospital of Fujian Medical University.They were divided into four groups according to the diagnosis results: Group A(intestinal tuberculosis group),Group B(Crohn’s disease group),Group C(not intestinal tuberculosis nor Crohn’s disease group)and Group D(uncertain group).The paper retrospective analyzed the differences in demographic characteristics,clinical symptoms,endoscopic manifestations and laboratory tests among the four groups,and then evaluated advantages and disadvantages of T-SPOT.TB,TST,TB antibody in distinguishing intestinal tuberculosis from non-intestinal-tuberculosis and the value of TSPOT.TB in the differential diagnosis of ileocecal lesions by analyzing the sensitivity,specificity,positive predictive value(PPV),negative predictive value(NPV),likelihood ratio+(LR +),likelihood ratio-(LR-)of T-SPOT.TB,TST,TB antibody and their joint tests in the diagnosis of tuberculosis and estimating the receiver operating characteristic(ROC)curve and consistency test.Results:(1)Demographic characteristics: The median age of Group B was lower than that of Group A,C and D(25.0 vs 37.0,47.0,34.5,P<0.0083),and there was no significant difference among Group A,C and D(P>0.05).The proportion of male in each group is higher than that of female(P<0.05),and there was no difference of the proportion among the groups(P>0.05).(2)Clinical symptoms: The incidence of hematochezia in Group C was higher than that in Group B(P<0.0083),and the incidence of perianal lesions in Group B was higher than that in Group C and D(27.0% vs 0%,2.5%,P<0.0083).The incidence of abdominal pain,diarrhea,fever,intestinal obstruction and intestinal perforation had no significant difference among the four groups.(3)Endoscopic manifestations: The intestinal stricture(40.0% vs 11.0%,8.3%,P<0.0083)and circular ulcer(28.0% vs 4.0%,0%,P<0.0083)were more common in Group A than in Group B and C.While the longitudinal ulcer(30.5% vs 4.0%,P<0.0083)and multisegmental lesions under endoscopy were more common in Group B than in Group A.The ileocecal valve involvement was more common in Groups A and B than in Groups C and D(60.0%,66.0% vs 13.9%,42.5%,P<0.0083).There was no significant difference in the incidence of the number of ulcers ≥ 2 or protrusion lesion detected by endoscopy among the four groups(P>0.05),and there was no significant difference in the incidence of "cobblestone sign" among Groups A,B and C(P>0.05).(4)Laboratory tests: The positive rate of TSPOT.TB in Group A was significantly higher than that in Group B,C and D(P<0.0083),and the positive rate of TST and TB antibody in Group A was higher than that in Group B(P<0.0083).There was no statistically significant difference about CRP and ESR among the four groups(P>0.05).(5)T-SPOT.TB has the sensitivity,NPV,LR + and LR-infinitely superior to those of TST and TB antibody(P<0.05),and the PPV superior to those of TST(P<0.05).Compared with T-SPOT.TB,the joint tests showed no obvious superiority in sensitivity,specificity,PPV and NPV(P>0.05).(6)The AUC of diagnosis of tuberculosis infection of T-SPOT.TB was 0.90,the AUC of TST was 0.68,that of TB antibody was 0.64,and that of joint test was 0.85.Based on the AUC,the diagnostic value of T-SPOT.TB was better for detection of TB infection in patients with ileocecal diseases.(7)Consistency test: The consistency test between T-SPOT.TB and the diagnostic criteria of intestinal tuberculosis was undertaken(kappa = 0.79,P<0.001),indicating the diagnosis results of these two methods have a high consistency.Conclusions: The ileocecal valve involvement is more common in the patients with ITB and CD.The characteristics like middle age onset,endoscopic circular ulcer,and intestinal stricture are more suggestive of the clinical diagnosis of ITB.T-SPOT.TB is more sensitive and accurate than TST and TB antibody detection in the diagnosis of ITB,and considering its high specificity and NVP,the negative results are helpful to exclude ITB.Since the diagnosis results of T-SPOT.TB are similar to the diagnostic criteria of ITB,it can be used as one of the main methods for differential diagnosis of tuberculous lesions in ileocecal region.