Diagnostic Value Of The Pleural Effusion Mononuclear Cells Proportion And T Cell Spot Test Of Tuberculosis Infection In Peripheral Blood For Tuberculous Pleurisy

Background:China is one of the countries with high tuberculosis(TB)burden worldwide.Tuberculous pleurisy(TBP)is a common clinical type of tuberculosis and its diagnosis is difficult.Pleural effusion cytology is an accurate,safe and rapid method commonly used to diagnose pleural diseases.Lymphocytes and monocytes dominate in tuberculous pleural effusion.However,lymphocytes and monocytes in pleural effusion are usually not differentiated in clinical practice.Currently,automated blood analyzers are widely used to count mononuclear cells,which include lymphocytes and monocytes.Existing literatures suggest that the proportion of lymphocytes and monocytes have certain clinical significance in the diagnosis of TBP.But there are few studies on whether the pleural effusion mononuclear cells proportion can be used to diagnose TBP and its value is unclear.In addition,T cell spot test of tuberculosis infection(T-SPOT.TB)in Peripheral blood is widely used in the diagnosis of tuberculosis,but the value for Chinese patients with TBP is controversial.The low diagnostic specificity is also necessary to study how to further improve.Objective:The purpose of the study was to evaluate the diagnostic value of the pleural effusion mononuclear cells proportion and T-SPOT.TB in peripheral blood for TBP patients.Methods:This study was a retrospective case-control study.We initially analyzed 406 patients with unknown pleural effusion from the Department of Respiratory Medicine at Henan Provincial People’s Hospital during January 1,2014 to September 1,2019.Finally,191 patients were excluded,and 215 patients were finally investigated in the current study,divided into 91 tuberculous pleurisy(TBP)patients and 124 non-tuberculous pleurisy(NTBP)patients with pleural effusion by the gold standard of the pathological results of thoracoscopic pleural biopsy.The results of the pleural effusion mononuclear cells proportion and peripheral blood T-SPOT.TB,and other medical record information including gender,age,and basic diseases,ect were collected.Receiver operating characteristic(ROC)curve were plotted to assess the optimal cut-off values and areas under the ROC curve(AUC)of the pleural effusion mononuclear cells proportion for TBP.Then the sensitivity(Sen),specificity(Spe),accuracy(Acc),positive predictive value(PPV),negative predictive value(NPV),positive likelihood ratio(LR+),negative likelihood ratio(LR-)of the pleural effusion mononuclear cells proportion,peripheral blood T-SPOT.TB and combined test for TBP diagnosis were investigated.Results:1.The level of pleural effusion mononuclear cells proportion in TBP group was 95.9%(89.7%,98.0%)higher than that in NTBP group 77.8%(39.3%,93.2%),and the difference was statistically significant(Z = 6.902,P < 0.001).2.The best cut-off value of pleural effusion mononuclear cells proportion for TBP diagnosis was 93.7%,with the Sen,Spe,Acc,PPV,NPV,LR+,LR-of 64.8%,79%,0.730,69.4%,75.4%,3.092,0.445,respectively.3.The Sen,Spe,Acc,PPV,NPV,LR+,LR-of peripheral blood T-SPOT.TB for TBP diagnosis was 92.3%,61.3%,0.744,63.6%,91.6%,2.385,0.126,respectively.4.Combination of pleural effusion mononuclear cells proportion and peripheral blood T-SPOT.TB test suggested diagnostic value for TBP.The Sen,Spe,Acc,PPV,NPV,LR+,LR-of serial test was 61.5%,90.3%,0.781,82.4%,76.2%,6.359,0.426;Above evaluation indexes of parallel test was 95.6%,50%,0.693,58.4%,93.9%,1.912,0.088.5.The sensitivity of parallel test(95.6%)was significantly higher than pleural effusion mononuclear cells proportion alone(64.8%)(X2= 5.026,P = 0.025)and peripheral blood T-SPOT.TB alone(92.3%)(X2 = 37.530,P < 0.001).The specificity of serial test(90.3%)was significantly higher than pleural effusion mononuclear cells proportion alone(79%)(X2 = 44.936,P < 0.001)and peripheral blood T-SPOT.TB alone(61.3%)(X2 = 18.273,P < 0.001).6.The AUC of pleural effusion mononuclear cells proportion and it combined with peripheral blood T-SPOT.TB was 0.776(95% CI,0.714-0.830)and 0.868(95% CI,0.815-0.910),respectively,with statistically significant difference(Z = 3.901,P < 0.001).Conclusion:1.The level of pleural effusion mononuclear cells proportion in TBP was higher than that in NTBP.Pleural effusion mononuclear cells proportion was useful for TBP diagnosis.2.Peripheral blood T-SPOT.TB had high sensitivity but low specificity for TBP diagnosis,which was easy to be misdiagnosed.3.The value of pleural effusion mononuclear cells proportion in combination with peripheral blood T-SPOT.TB for TBP diagnosis was better than that of the two alone for TBP diagnosis.The higher sensitivity of the parallel test was helpful to reduce missed diagnosis.The higher specificity of the series test was helpful to reduce misdiagnosis.