Association of Radiological Findings with the Xpert MTB/RIF Test in Patients with Suspected Pulmonary Tuberculosis

Purpose

Tuberculosis (TB) treatment is often carried out empirically, based on clinical and radiological findings. Chest X-ray (CXR) has good sensitivity but poor specificity in TB diagnosis. Xpert MTB/RIF (Mycobacterium tuberculosis/Rifampicin) is increasingly used in many countries as the initial diagnostic test for TB. The aim of the present study was to evaluate the association of radiological findings with the Xpert MTB/RIF test in patients with suspected pulmonary TB.

Methods

Cross-sectional study in an outpatient TB clinic. Sputum AFB smear, culture, Xpert MTB/RIF, and CXR were collected in patients with suspected pulmonary TB.

Results

During the study period, 312 patients met the inclusion criteria and were included in the analysis. Among Xpert MTB/RIF-positive cases, the radiographic patterns were classified as typical of TB, compatible of TB, and normal in 78 (70.3%), 31 (27.9%), and 2 (1.8%) patients, respectively. CXRs were classified as typical of TB, compatible of TB, and normal in 20 (10.0%), 25 (12.4%), and 152 (75.6%) patients, respectively, in Xpert MTB/RIF-negative cases.

Conclusions

We found an association between radiographic patterns and Xpert MTB/RIF results in patients with suspected pulmonary TB. These results confirm the current recommended diagnosis algorithm.

     

Pattern of missing probes in rifampicin resistant TB by Xpert MTB/RIF assay at a tertiary care centre in Mumbai

Setting

Department of Microbiology.

Post-treatment change in Mycobacterium tuberculosis antigen-stimulated tumor necrosis factor-alpha release in patients with active tuberculosis

Background

Monitoring tuberculosis (TB) treatment response remains challenging due to lack of reliable laboratory markers. In recent years, increased efforts have been exerted toward development of new biomarkers reflecting treatment response appropriately. While performance of interferon-gamma release assays (IGRAs) to monitor anti-TB treatment has been extensively evaluated, there is no data about post-treatment changes in Mycobacterium tuberculosis (MTB) antigen-stimulated tumor necrosis factor-alpha (TNF-α) release in active TB patients. Herein, we explored whether the MTB antigen-stimulated TNF-α release would be useful for monitoring responses to anti-TB treatment.

Methods

We compared unstimulated (TNF-α_Nil), MTB antigen-stimulated (TNF-α_Ag), and MTB antigen-stimulated minus unstimulated TNF-α levels (TNF-α_Ag-Nil) in supernatants from QuantiFERON-TB Gold In-Tube tests before and after treatment in 16 active TB patients, 25 latent TB infection (LTBI) subjects, and 10 healthy controls (HC).

Results

TNF-α_Ag and TNF-α_Ag-Nil levels decreased significantly after treatment in patients with active TB. In addition, TNF-α_Nil, TNF-α_Ag, and TNF-α_Ag-Nil levels were significantly higher in untreated active TB patients compared to LTBI subjects and HC.

Conclusions

This finding cautiously suggests that MTB Ag-stimulated TNF-α response may be a potential adjunctive marker for monitoring treatment response in active TB patients.     

Thoracoscopic pleural biopsy improves yield of Xpert MTB/RIF for diagnosis of pleural tuberculosis

Background and objective

Extrapulmonary tuberculosis (EPTB) accounts for ~15% of all TB patients, and TB pleural effusion is the second most common site of EPTB. The diagnosis of pleural TB is challenging due to the pauci‐bacillary nature of the disease. Histopathology of thoracoscopically obtained pleural biopsy provides the highest diagnostic yield. The Xpert MTB/RIF assay (Xpert) is a PCR test that can identify both Mycobacterium tuberculosis (MTB) and rifampicin resistance. Currently, there is a lack of clarity regarding the value of Xpert on pleural tissue. We report our experience of using Xpert on thoracoscopic pleural biopsy samples.

Methods

We retrospectively reviewed the records of patients who underwent thoracoscopy in our institution over a 1‐year period. Relevant clinical details; indications; and results of tests on pleural tissue and fluid, including histopathology, mycobacterial cultures and Xpert, were extracted.

Results

Of the 156 patients who underwent thoracoscopy, 73 (47%) had TB, 66 (42%) malignancy and 17 (11%) other conditions. Histopathology was diagnostic in all the 73 TB patients (100%). The yields of the microbiological tests against histopathology on thoracoscopic biopsy sample and pleural fluid were: pleural tissue Xpert 45%, pleural tissue culture 39%, pleural fluid culture 17% and pleural fluid Xpert 14%. Pleural tissue provided higher yields than fluid in both Xpert and culture (P < 0.05). Pleural tissue Xpert provided a higher yield than culture and substantially improved yield compared with closed pleural biopsy as we previously reported.

Conclusion

Thoracoscopic pleural biopsy results in increased sensitivity on Xpert testing.

     

Performance of Xpert MTB/RIF for detection of Mycobacterium tuberculosis and rifampicin resistance in pus aspirates

IntroductionWHO endorsed Xpert MTB/RIF assay has proven to be rapid with results obtained within 2 h. The evidence base regarding the use of Xpert MTB/RIF in pulmonary TB is strong. Relatively few performance data have been published to date on detection of Mycobacterium tuberculosis in aspirated pus specimens from abscesses.ObjectivesThe aim of the study was to determine the sensitivity and specificity of Xpert MTB/RIF assay for the detection of M. tuberculosis and rifampicin resistance in aspirated pus specimens using culture on Lowenstein Jensen (LJ) medium and economic variant of proportion method (PM) for drug susceptibility testing (DST) as the reference standard.ResultsXpert MTB/RIF assay in comparison to conventional reference method showed sensitivity and specificity of 76.19% and 68.75% for detection of M. tuberculosis and 71.4% and 100% for detection of rifampicin resistance respectively.ConclusionThe simplicity, sensitivity, speed and automation makes this assay a very promising diagnostic test for detection of M. tuberculosis and rifampicin resistance in aspirated pus specimens.     

Regional differences of nontuberculous mycobacteria species in Ulsan,Korea

Background

In Korea recently, nontuberculous mycobacteria (NTM) have been more frequently isolated in respiratory specimens, while Mycobacterium tuberculosis (MTB) isolations have decreased. The major NTM lung disease species in Korea are M. intracellulare, M. avium, and M. abscessus, whereas M. kansasii is a rare species. This retrospective study was performed to determine if there are region-specific characteristics of lung disease-causing NTM species in Ulsan, a highly industrialized city in Korea.

Methods

Between January 2010 and July 2013, the results of all acid-fast bacilli (AFB) cultures of respiratory specimens performed at Ulsan University Hospital (Ulsan, Korea) were collected. NTM were identified and regional differences of NTM species were compared.

Results

AFB cultures were performed on 33,567 respiratory specimens, obtained from 10,208 patients, during the study period. Further, 10% of the specimens (3,287/33,567) were AFB culture-positive [MTB, 2,288/3,287 (70%); NTM 999/3,287 (30%)]. The proportion of NTM isolations gradually increased between 2010 and 2013, at 25% and 38%, respectively. The most common NTM species was M. intracellulare (356/999, 36%), followed by M. kansasii (295/999, 30%), M. avium (161/999, 16%), M. abscessus (117/999, 12%) and M. fortuitum (39/999, 4%). This trend was maintained throughout the study period.

Conclusions

In Ulsan, NTM isolation from respiratory specimens is increasing, consistent with previous studies performed in Korea. The distribution of respiratory NTM species, however, differed from previous studies that were performed in other regions of Korea: M. kansasii was the second most common NTM species in Ulsan. In Ulsan, there is a regional difference in the NTM species isolated.     

结核分枝杆菌/利福平耐药实时荧光定量核酸扩增检测技术诊断艾滋病患者肺结核的临床应用评价

目的:探讨结核分枝杆菌(Mycobacterium tuberculosis,MTB)/利福平耐药实时荧光定量核酸扩增检测(Xpert MTB/RIF)技术诊断艾滋病患者肺结核的应用价值。方法:回顾性分析2017年7月至2019年11月上海市(复旦大学附属)公共卫生临床中心收治的226例疑似肺结核的艾滋病患者的临床资料。分别进行痰涂片荧光染色显微镜下检查、BACTEC MGIT 960液体培养(或罗氏固体培养)和Xpert MTB/RIF检测,并分析在艾滋病患者中Xpert MTB/RIF技术诊断MTB感染和利福平耐药的灵敏度和特异度。结果:226例疑似肺结核患者中,痰培养阳性94例(41.6%),其中MTB阳性51例(54.3%),非结核分枝杆菌(nontuberculosis mycobacteria,NTM)阳性43例(45.7%)。以痰分枝杆菌培养阳性且结核分枝杆菌分泌蛋白64抗原阳性为金标准,Xpert MTB/RIF技术诊断MTB的灵敏度为72.6%[95%可信区间(confidence interval,CI)66.7%~78.4%],特异度为97.1%(95%CI 95.0%~99.3%)。Xpert MTB/RIF技术诊断痰涂片阳性患者MTB的灵敏度为76.7%(95%CI 67.7%~85.8%),特异度为90.0%(95%CI 83.6%~96.5%)。Xpert MTB/RIF技术诊断痰涂片阴性患者MTB的灵敏度为50.0%(95%CI 41.8%~58.2%),特异度为99.3%(95%CI 97.9%~100.0%)。18例患者同时检测利福平表型和基因型耐药,以表型耐药为金标准,Xpert MTB/RIF技术检测利福平基因型耐药的灵敏度为75.0%,特异度为100.0%。结论:艾滋病患者中Xpert MTB/RIF技术诊断肺结核的灵敏度和特异度均较高,且能快速区分MTB和NTM,具有较好的应用价值。     

Clinical application and research progress of Xpert MTB/RIF Ultra and Xpert MTB/RIF tests

结核病(TB)是目前全球最严重的传染性疾病之一,利福平耐药实时荧光定量核酸扩增(Xpert MTB/RIF,简称“Xpert”)检测技术作为一种快速检测结核分枝杆菌(MTB)和利福平耐药性的方法,以较高的敏感度和特异度为TB的诊断和治疗提供了可靠的信息,但其本身还存在一些不足和局限。2017年3月,世界卫生组织(WHO)推荐新一代检测方法——超敏结核分枝杆菌和利福平耐药基因检测(Xpert MTB/RIF Ultra,简称“Xpert Ultra”)替代Xpert检测。与Xpert检测相比, Xpert Ultra检测对含菌量少的标本检测敏感度更高,如肺外结核、TB并发艾滋病、儿童结核病等,对于正确选择治疗药物、制定合理的治疗方案有重要的意义。作者对Xpert技术的局限性及其与Xpert Ultra的异同进行综述,为Xpert Ultra在临床中的应用提供依据。     

Comparison of four DNA extraction methods for detecting Mycobacterium tuberculosis by real-time PCR and its clinical application in pulmonary tuberculosis

Objectives

China is one of the countries with a high burden of Mycobacterium tuberculosis (MTB) infection. One challenge for the earlier diagnosis of tuberculosis is the DNA extraction of MTB. This study was to compare four MTB DNA extraction methods, and use the best one in the diagnosis of pulmonary tuberculosis.

Methods

A total of 43 serum and 94 plasma samples were collected from 124 clinical diagnosed pulmonary tuberculosis patients. Four different MTB DNA extraction methods, including phenol-chloroform method, Qiagen kit, Omega kit and magnetic bead method, were compared to determine which method displayed the highest sensitivity. A quantitative fluorescent PCR assay was also designed for the detection of MTB DNA.

Results

The highest DNA extraction efficiency (52.8%) and the best reproducibility (coefficient of variance =26.7%) were observed using the magnetic bead method. For 39 of the 124 (31.5%) pulmonary tuberculosis patients, MTB DNA was detected in their plasma or serum samples. Interestingly, 35.3% (12/34) of smear-negative cases were MTB DNA positive.

Conclusions

In conclusion, magnetic bead method is the best one for the DNA extraction of MTB. The detection of MTB DNA may provide valuable information for the diagnosis of acid-fast bacilli (AFB) negative pulmonary tuberculosis patients.KEY WORDS : Mycobacterium tuberculosis (MTB), pulmonary tuberculosis, plasma DNA, quantitative fluorescent PCR     

GeneXpert MTB/RIF for rapid diagnosis and rifampin resistance detection of endobronchial tuberculosis

Background and objective

Delayed diagnosis and treatment of tuberculosis (TB) contribute to poor outcomes, especially for endobronchial TB (EBTB), which typically leads to tracheobronchial stenosis. Finding rapid and accurate diagnostic tools for EBTB is crucial. GeneXpert Mycobacterium tuberculosis (MTB)/rifampin (RIF) was recommended by the World Health Organization (WHO) as a standard molecular biological diagnostic technique for MTB. The aim of this study was to evaluate the efficacy of GeneXpert MTB/RIF for diagnosing EBTB and for evaluating RIF resistance.

Methods

Biopsy tissue and bronchial brushings from EBTB patients were prospectively assessed with GeneXpert MTB/RIF. The diagnostic yields of auramine O‐stained sputum smears and bronchial brush smears were obtained, and the results were compared with the cultures of sputum and biopsy tissues for MTB.

Results

In 61 confirmed cases of EBTB, the sensitivities of sputum smear, bronchial brush smear, sputum culture and tissue culture to diagnose EBTB were 13.1%, 32.8%, 36.1% and 68.9%, respectively. For bronchial brushings and biopsies, our data showed sensitivities of 57.4% and 63.9%, respectively, and a specificity of 100% for GeneXpert MTB/RIF, and these results were superior to those of sputum smears, bronchial brush smears and sputum culture. GeneXpert MTB/RIF for bronchial brushings and biopsies showed complementarity in its diagnostic performance. Resistance to RIF was identified in 17.4% (8/46) of GeneXpert MTB‐positive cases.

Conclusion

GeneXpert MTB/RIF may enable more rapid EBTB diagnosis and determination of RIF resistance, which are crucial for timely treatment.

     

Incidence and Clinical Outcomes of Clostridium difficile Infection after Treatment with Tuberculosis Medication

Background/Aims

To determine the incidence and clinical characteristics of tuberculosis (TB) medication-associated Clostridium difficile infection.

Methods

This multicenter study included patients from eight tertiary hospitals enrolled from 2008 to 2013. A retrospective analysis was conducted to identify the clinical features of C. difficile infection in patients who received TB medication.

Results

C. difficile infection developed in 54 of the 19,080 patients prescribed TB medication, representing a total incidence of infection of 2.83 cases per 1,000 adults. Fifty-one of the 54 patients (94.4%) were treated with rifampin. The patients were usually treated with oral metronidazole, which produced improvement in 47 of the 54 patients (87%). Twenty-three patients clinically improved with continuous rifampin therapy for C. difficile infection. There were no significant differences in improvement between patients treated continuously (n=21) and patients in whom treatment was discontinued (n=26).

Conclusions

The incidence of C. difficile infection after TB medication was not low considering the relatively low TB medication dosage compared to other antibiotics. It may not be always necessary to discontinue TB medication. Instead, decisions concerning discontinuation of TB medication should be based on TB status.     

Performance of Xpert MTB/RIF assay on thoracoscopic pleural biopsy in undiagnosed exudative pleural effusion

AimsThe aim of the study was to determine the performance of Xpert MTB/RIF assay in diagnosing tuberculosis on thoracoscopic pleural biopsies in exudative pleural effusion.MethodsPatients who underwent thoracoscopic pleural biopsy in the defined period were included in the study. Histopathology was done for all and Xpert MTB RIF assay and AFB culture of pleural biopsy specimen and pleural fluid were done as per the clinician's discretion.ResultsTotal of 110 patients underwent pleural biopsy and tissue Xpert MTB/RIF and MTB culture were done in 29 patients. XpertMTB/RIF assay and MTB culture had a sensitivity of 59% and 35% respectively and specificity of specificity of 100.ConclusionThe study described the ability of XPERT MTB/RIF in getting additional diagnostic information from thoracoscopic Pleural biopsy. Pleural biopsy Xpert MTB/RIF had sensitivity of 59% and specificity of 100% in diagnosing TPE. In addition to the diagnosis, Xpert MTB/RIF can also give valuable information about rifampicin resistance too. XPERT MTB/RIF assay also helped in getting diagnosis when histopathology alone was not able to confirm or rule out the diagnosis of TPE. Pleural fluid ADA of 38 IU/L had a sensitivity of 71% and a specificity of 86% for diagnosis of TPE in present study.     

Diagnosis of pneumocystis pneumonia using serum (1-3)-β-D-Glucan: a bivariate meta-analysis and systematic review

Background

The (1-3)-β-D-Glucan (BG) assay has been approved for making a diagnosis of invasive fungal disease. However, the role of serum-BG assay for the diagnosis of pneumocystis pneumonia (PCP) is controversial, especially between patients with human immunodeficiency virus (HIV) and non-HIV. We conducted a meta-analysis to determine the difference of the overall accuracy of serum-BG assay for the diagnosis of PCP in immunocompromised patients with and without HIV.

Methods

After a systematic review of English-language studies and manual researching, sensitivity (Se), specificity (Sp), and other measures of accuracy of serum-BG for the diagnosis of PCP were pooled using random-effects models for bivariate meta-analysis. Summary receiver operating characteristic (SROC) curve was used to summarize overall test performance. Subgroup analyses were performed to explore the heterogeneity in Se and Sp.

Results

Thirteen studies met our inclusion criteria. The summary estimates for serum-BG assay for definite PCP were as follows: Se, 0.91 [95% confidence interval (CI), 0.88–0.93]; Sp, 0.75 (95% CI, 0.68–0.81). As for the patients with and without HIV, the Se and Sp were 0.92 and 0.78, 0.85 and 0.73, respectively. Significant heterogeneity between Se was presented (P=0.04).

Conclusions

Contrary to the results of the previous meta-analysis, a negative result of serum-BG determination is sufficient for ruling out PCP only in HIV cases. For non-HIV patients, the results should be interpreted in parallel with clinical and radiological findings. Besides, further prospective studies with larger sample size are needed to confirm the diagnosis strategy of BG detection.     

Xpert MTB/RIF对结核菌利福平耐药的诊断价值及rpoB基因突变特点的分析

目的分析Xpert MTB/RIF检测对结核分枝杆菌利福平耐药的诊断价值及rpoB基因突变特点。方法回顾分析2016年1月至2020年6月期间来院就诊患者相同标本,同时进行了结核分枝杆菌培养及药敏试验和Xpert MTB/RIF检测,且任一种方法检出MTB。结果用Xpert MTB/RIF及培养药敏两种方法检测标本共7659例,Xpert MTB/RIF对MTB的检出率高,且有统计学意义(P<0.05)。两种方法同时检出MTB 3621例,Xpert MTB/RIF检出利福平耐药262例,培养药敏检出利福平耐药238例;两种方法检测利福平耐药的一致率为99.01%;采用Kappa检验,两种方法的检测结果完全符合。RR-TB探针突变的频率为E探针63.37%、D探针20.16%、B探针8.23%、A探针4.53%、C探针0.82%、联合探针突变2.88%;以培养药敏结果为利福平耐药的金标准,Xpert无探针突变组利福平耐药的准确性要明显低于有探针突变组;初治和复治病例探针突变频率差异有统计学意义。结论Xpert MTB/RIF检测可以快速有效的诊断利福平耐药结核,有助于早发现、早治疗。利福平耐药结核探针突变主要发生在E探针和D探针,C探针突变最少。     

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the identification of beta-hemolytic streptococci

Objective

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as promising technology for species identification. The purpose of this investigation was to compare the performance of MS and the traditional method for identification of beta-hemolytic streptococci (BHS).

Methods

Clinical BHS isolates were identified by the BD Phoenix SMIC/ID Streptococcal panels, and two MALDI-TOF MS platforms: the VITEK MS and the Bruker MALDI Biotyper systems respectively. In case of discordant results, 16sRNA sequencing was performed to provide the reference ID.

Results

A total of 96 isolates of BHS were analyzed. Thirty-six isolates (20.8%) were re-tested by BD Phoenix for identification failure; and four isolates (4.2%) were rerun on the Bruker system for low identification score. No isolate need a second run for identification by Vitek MS system. Overall, BD Phoenix, BioTyper and Vitek MS automated system accurately identified 76 strains (79.2%), 91 (94.7%) strains and 92 (95.8%) strains, respectively.

Conclusions

Our study suggests that MALDI-TOF MS is a superior method to conventional phenotypic methods for BHS identification.     

Evaluation of amplification targets for the specific detection of Bordetella pertussis using real-time polymerase chain reaction

BACKGROUND:

Bordetella pertussis infections continue to be a major public health challenge in Canada. Polymerase chain reaction (PCR) assays to detect B pertussis are typically based on the multicopy insertion sequence IS481, which offers high sensitivity but lacks species specificity.

METHODS:

A novel B pertussis real-time PCR assay based on the porin gene was tested in parallel with several previously published assays that target genes such as IS481, ptx-promoter, pertactin and a putative thialase. The assays were evaluated using a reference panel of common respiratory bacteria including different Bordetella species and 107 clinical nasopharyngeal specimens. Discrepant results were confirmed by sequencing the PCR products.

RESULTS:

Analytical sensitivity was highest for the assay targeting the IS481 element; however, the assay lacked specificity for B pertussis in the reference panel and in the clinical samples. False-positive results were also observed with assays targeting the ptx-promoter and pertactin genes. A PCR assay based on the thialase gene was highly specific but failed to detect all reference strains of B pertussis. However, a novel assay targeting the porin gene demonstrated high specificity for B pertussis both in the reference panel and in clinical samples and, based on sequence-confirmed results, correctly predicted all B pertussis-positive cases in clinical samples. According to Probit regression analysis, the 95% detection limit of the new assay was 4 colony forming units/reaction.

CONCLUSION:

A novel porin assay for B pertussis demonstrated superior performance and may be useful for improved molecular detection of B pertussis in clinical specimens.     

Leishmania infantum DNA detection in Phlebotomus tobbi in a new northern focus of visceral leishmaniasis in Iran

Objective

To identify the vector(s), the parasite and the species composition of sand flies in the district during May-October 2012.

Methods

For reaching our objectives we used polymerase chain reaction of kDNA, ITS1-rDNA, followed by restriction fragment length polymorphism.

Results

Two species of Phlebotomus sergenti and Phlebotomus tobbi were the most prevalent among 8 species identified comprising 51.1% and 32.9% respectively. Among the 160 specimens of female sand flies tested by polymerase chain reaction of kDNA, ITS1-rDNA, followed by restriction fragment length polymorphisms, only 1 out of 80 Phlebotomus tobbi (1.25%) were positive to Leishmania infantum parasites.

Conclusions

Our finding showed that Phlebotomus tobbi may play as a vector to circulate the parasite of Leishmania infantum among reservoir(s) and human.     

Detection of Helicobacter pylori in Gastric Aspirates Using a Monoclonal Antibody-Based Test

Background/Aims

The objective of this study was to evaluate a monoclonal antibody-based test to detect Helicobacter pylori-specific antigen in gastric aspirates from humans.

Methods

Sixty-one volunteers were enrolled in the study. All of the subjects underwent a ¹³C-urea breath test (UBT) before esophagogastroduodenoscopy. Gastric aspirates were analyzed for pH and ammonia and used for polymerase chain reaction (PCR), culture, and monoclonal antibody-based detection of H. pylori. Multiple biopsies of the gastric antrum and body were obtained for a rapid urease test (RUT) and histological evaluation.

Results

Thirty-six subjects were H. pylori-positive and 25 were H. pylori-negative according to the UBT results. Compared with the H. pylori-negative subjects, H. pylori-positive subjects had a higher pH (4.77±1.77 vs 3.49±1.30, p<0.05) and ammonia level (1,130.9±767.4 vs 184.2±126.3, p<0.0001). The sensitivities and specificities of the PCR test, RUT, culture test, and monoclonal antibody-based test were 100% and 72%, 89% and 100%, 47% and 100%, and 78% and 100%, respectively.

Conclusions

The monoclonal antibody-based test for diagnosing H. pylori infection in gastric aspirates has increased sensitivity compared with the culture test and specificity as high as that of the RUT. The test may be useful as an additive test for examining gastric aspirates.     

Expression of paired basic amino acid-cleaving enzyme 4 (PACE4) correlated with prognosis in non-small cell lung cancer (NSCLC) patients

Background

Paired basic amino acid-cleaving enzyme 4 (PACE4) was shown to enhance tumor cells proliferation and invasive. This study provides the first investigation of PACE4 expression in non-small cell lung cancer (NSCLC) and the correlation with clinicopathologic features, prognostic indicators of 172 cases.

Methods

Quantitative real-time PCR (RT-PCR) and immunofluorescence (IF) were applied to detect PACE4 expression in NSCLC and 16HBE cell lines, then 172 consecutive NSCLC and 15 normal lung tissues were studied through immunohistochemistry (IHC). The association between PACE4 expression and clinicopathological parameters was evaluated. Kaplan-Meier survival analysis and Cox proportional hazards models were used to estimate the effect of PACE4 expression on survival.

Results

PACE4 expression in NSCLC were significantly higher than normal lung cell and tissues (P<0.05). PACE4 had cytoplasmic expression and was observed in 111 of the 172 (64.5%) NSCLC patients. Clinicopathologically, PACE4 expression was significantly associated with lymph node metastasis (N stage) (P=0.007), and clinical stage (P=0.024). Multivariable analysis confirmed that PACE4 expression increased the hazard of death after adjusting for other clinicopathological factors [hazards ratio (HR): 1.584; 95% confidence interval (CI): 1.167-2.151; P<0.001]. Overall survival (OS) was significantly prolonged in PACE4 negative group when compared with PACE4 positive group (5-year survival rates, 23.1% vs. 54.5%, log-rank test, χ²=17.717, P<0.001), as was disease-free survival (DFS) (5-year survival rates, 23.4% vs. 55.4%, log-rank test, χ²=20.486, P<0.001).

Conclusions

Our results suggest that positive expression of PACE4 is an independent factor for NSCLC patients and it might serve as a potential prognostic biomarker for patients with NSCLC.