Diagnostic Value Of Xpert MTB/RIF Ultra For Smear-negative Pulmonary Tuberculosis、tuberculous Pleurisy And Tuberculous Meoingitis

Backgroud:Tuberculosis(TB)is the ninth most deadly disease around the world.The specimens of extrapulmonary tuberculosis and smear-negative tuberculosis patients harbor scarce bacteria and have low positivity rate for pathogen detection,which may lead to misdiagnosis.Real-time quantitative nucleic acid amplification assay(Xpert MTB/RIF,Xpert)can rapidly diagnose tuberculosis and its rifampicin resistance,and plenty of studies had validated its efficiency for TB diagnosis.In 2010 and 2013,the World Health Organization(WHO endorsed this techniques for diagnosis of tuberculosis,extrapulmonary tuberculosis and tuberculosis in children,respectively.However,it is already known that Xpert had low efficiency for paucibacillary specimen such as smear-negative sputa and extra-pulmonary specimens.The Cepheid company developed a new generation of technique named Xpert MTB/RIF Ultra(Xpert Ultra)to overcome the low sensitivity of Xpert.WHO plans to recommend Xpert Ultra as an alternative to Xpert for TB diagnosis.However,large-scale evaluation of Xpert Ultra among patients from different regions is needed before its universally clinical application,and sufficient evidences are indispensable before WHO releasing a recommendation for this diagnostic tool.This study aimed to investigate the diagnostic value of Xpert Ultra for smear-negative tuberculosis and extrapulmonary tuberculosisPart One Diagnostic value of Xpert MTB/RIF Ultra for smear-negative pulmonary tuberculosisObjective:To evaluate the diagnostic value of Xpert MTB/RIF Ultra in patients with smear-negative pulmonary tuberculosis.Method:The sputum samples of suspected pulmonary tuberculosis patients from the Beijing Chest Hospital affiliated to Capital Medical University were collected from July to December 2017.Each specimen was subjected to acid-fast staining smear microscopy and mycobacterial rapid culture(BACTECTM MGIT 960).Roche solid culture and Xpert test,and the remaining sputum samples after alkali treatment and neutralization were stored at-80 Cfor use.For patients with negative smears,samples stored at-80℃ were used for Xpert Ultra testing.The culture-positive M.tuberculosis was tested by the Drug susceptibility testing(DST).The diagnostic value of Xpert Ultra and Xpert for smear-negative pulmonary tuberculosis was evaluated using the composite reference standard(CRS)as the gold standard.CRS included clinical presentation,pathogenic examination,histopathological features,imaging findings,and at least 6 months follow-up.Results:A total of 292 cases of smear-negative tuberculosis and 206 cases of non-tuberculosis were included.The sensitivity of Xpert Ultra(70.89%,207/292)was significantly higher than that of Xpert(57.88%,169/292,P=0.001).The results of stratified analysis showed that the sensitivity of Xpert Ultra(87.18%,102/117)in smear-negative and culture-positive tuberculosis was also significantly higher than that of Xpert(76.92%,90/117,P=0.041);Xpert Ultra is more detailed than Xpert’s sensitivity(60.00%,105/175 vs 45.14%,79/175,P=0.009).Xpert Ultra specificity(96.60%,199/206)was slightly lower than Xpert(98.06%,202/206,P=0.154),but the difference was not statistically significant.In 16 patients with rifampicin resistance and 74 RIF-sensitive patients,the sensitivity of Xpert Ultra for rifampicin resistance was 100%(16/16)and the sensitivity of Xpert was 93.75%(DST was used as the gold standard).15/16),the specificity is 100%(74/74).Conclusion:Xpert Ultra has higher sensitivity than Xpert assay,but its specificity is slightly reduced.Xpert Ultra can be used to diagnose small bacterial tuberculosis.Especially in the diagnosis of smear-negative tuberculosis.Part Two Diagnostic value of Xpert MTB/RIF Ultra for tuberculous pleurisyObjective:To evaluate the diagnostic value of Xpert MTB/RIF Ultra in patients with tuberculous pleurisy.Method:Beijing Chest Hospital affiliated to Capital Medical University in 2014 undertook the Beijing Municipal Science and Technology Commission’s key project"Diagnostic and Normative Treatment of Tuberculous Pleurisy"(D141107005214003),which continuously included more than 400 patients with suspected tuberculous pleurisy.The patient’s pleural effusion was tested by smear,culture,and Xpert.The pleural effusion specimens collected from each patient were stored at-80℃.The final diagnosis of each patient was determined by follow-up of the patients for at least 1 year.This study was continuously included in the study-Xpert Ultra test for pleural effusion specimens stored at 80℃.The positive culture of Mycobacterium tuberculosis was tested by proportional DST.The diagnostic value of Xpert Ultra and Xpert for tuberculous pleurisy was evaluated using CRS as the gold standard.CRS includes clinical presentation,pathogen examination,pleural effusion laboratory examination,histopathological examination,thoracoscopic examination,imaging findings,and at least 1 year follow-up.Results:A total of 208 patients with tuberculous pleurisy and 84 patients with non-tuberculosis were enrolled.The sensitivity of Xpert Ultra(44.23%,92/208)was higher than that of Xpert(19.23%,40/208,P<0.001).The sensitivity of Xpert Ultra in tuberculous pleurisy(83.64%,46/55)was also higher than that of Xpert(50.91%,28/55,P<0.001).For non-tuberculosis patients,the specificity of Xpert and Xpert Ultra was 98.67%(83/84).In 5 patients with rifampicin resistance and 22 RIF-sensitive patients(DST was used as the gold standard),the sensitivity of Xpert Ultra and Xpert for rifampicin resistance were 100%(5/5)both,and the specificity of Xpert and Xpert Ultra were 100%(22/22)both either.Conclusion:Compared with Xpert,Xpert Ultra has a higher sensitivity in the detection of tuberculous pleurisy patients and is of great value for the diagnosis of patients.Part Three Diagnostic value of Xpert MTB/RIF Ultra for tuberculous meningitisObjective:To evaluate the diagnostic value of Xpert MTB/RIF Ultra in patients with tuberculous meningitis.Method:Cerebrospinal fluid samples from suspected tuberculous meningitis patients from Beijing Chest Hospital affiliated to Capital Medical University from July to December 2017 were collected.Each specimen was tested for acid-fast staining smear and rapid culture of mycobacteria(BACTECTM MGIT 960)Roche solid culture and Xpert test,and the remaining cerebrospinal fluid samples were stored frozen at-80 0C for use.Xpert Ultra detection was performed using a specimen stored at-80℃.The positive culture of Mycobacterium tuberculosis was tested by proportional DST.The diagnostic value of Xpert Ultra and Xpert for tuberculous meningitis was evaluated using CRS as the gold standard.CRS includes clinical presentation,pathogen examination,cerebrospinal fluid laboratory examination,cranial imaging findings,and at least 6 months follow-up.Results:43 patients with tuberculous meningitis and 17 patients with non-tuberculosis were included The results of pathological experiments were used as reference standards.The sensitivity of Xpert Ultra detection(86.36%,19/22)was higher than that of Xpert(36.36%,8/22,P=0.001).Xpert Ultra detection sensitivity(44.19%,19/43)was also higher than Xpert(18.60%,8/43,P=0.011)for all patients.The specificity of both Xpert Ultra and Xpert is 100%(17/17).The culture test results of cerebrospinal fluid in 3 patients were positive,of which 1 was Xpert positive and 2 were Xpert Ultra positive.There were no culture tests and Xpert and Xpert Ultra tests for positive samples,so the accuracy of Xpert and Xpert Ultra for rifampicin resistance testing was not evaluated.Conclusion:Compared with Xpert,Xpert Ultra has a higher sensitivity in the detection of tuberculous meningitis patients and is of great value for the diagnosis of patients.Part Four An incremental cost-effectiveness analysis of the second Xpert MTB/RIF assay in the diagnosis of tuberculosisObjective:To study the incremental cost-effectiveness of the second Xpert assay in detection of Mycobacterium tuberculosis(Mtb)and rifampicin(RIF)resistance.Methods We continuously collected 2 896 specimens from suspected tuberculosis patients who had undergone 2 Xpert tests in a week from March 2015 to March 2018,including 2 402 suspected tuberculosis patients with 1 523 males and 879 females,with an average age of 46 years.Among them,2 144 specimens of sputum and 258 cases of bronchoalveolar lavage fluid were collected,which were included in the tuberculosis group.We also enrolled 494 patients with suspected extrapulmonary tuberculosis,318 males and 176 females,with an average age of 42 years.Among them,157 pleural effusion specimens,106 cerebrospinal fluid specimens,34 urine specimens and 197 pus specimens were collected,which were included in the extrapulmonary tuberculosis group.All specimens were subjected to two Xpert tests,smear microscopy,liquid rapid culture(BACTEC MGIT 960),and positively cultured bacteria were tested for drug susceptibility.According to the smear test results,the tuberculosis group and the extrapulmonary tuberculosis group included their corresponding smear-negative tuberculosis group and smear-positive tuberculosis group,smear-negative extrapulmonary group and smear-positive extrapulmonary groupResults Among the 2 896 specimens from suspected tuberculosis patients,either one of the two Xpert test results was positive(including both tests were positive,the same below)in 1 639 patients,and 1 502(91.64%)were positive in the first Xpert tests.The additional 137(8.36%)test results were positive in the second tests.The value-added efficacy of the second Xpert test in the smear-negative group(108/727,14.86%)was significantly higher than that in the smear-positive group(29/912,3.18%)(x2=221.404,P<0.001),and the extrapulmonary tuberculosis group(23/206,11.17%)was higher than the tuberculosis group(114/433,7.96%)(x2=2.422,P=0.012).Of the susceptibility test results,a total of 371 were rifampicin-resistant specimens.The first Xpert detected 91.4%(339/371),and the second Xpert detected the additional 8.13%(30/371).The cost increase of the second test was very significant.Tests were calculated at 650 yuan per time,the average cost of the first and second tests of the pulmonary tuberculosis group was 0.12 million yuan and 0.22 million yuan(P<0.001),and the value added cost was 1.37 million yuan;the average cost of the first and second tests of the extrapulmonary tuberculosis group The cost was 0.18 million yuan and 0.31 million yuan(P<0.001),and the value-added cost was 1.4 million yuan(corresponding with tuberculosis group,value added cost P<0.001).In the test of specimens of tuberculosis and extrapulmonary tuberculosis,the smear-negative specimen cost increase of the second Xpert test was lower than that of the smear-positive specimen.Conclusion:The second xpert test has significant value-added cost-effectiveness in the diagnosis of tuberculosis.