- Email: [email protected]
RIF in Brazil
Respiratory Medicine 134 (2018) 12–15
Contents lists available at ScienceDirect
Respiratory Medicine journal homepage: www.elsevier.com/locate/rmed
Diagnostic performances of the Xpert MTB/RIF in Brazil a,b,∗,1
c,1
d,e,1
T b,f
Denise Rossato Silva , Giovanni Sotgiu , Lia D'Ambrosio , Giovana Rodrigues Pereira , Márcia Silva Barbosag, Natan José Dutra Diash, Laura Saderic, Rosella Centisd, Giovanni Battista Migliorid,∗∗ a
Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil Programa de Pós-Graduação em Ciências Pneumológicas da UFRGS, Porto Alegre, Brazil c Clinical Epidemiology and Medical Statistics Unit, Department of Biomedical Sciences, University of Sassari, Sassari, Italy d World Health Organization Collaborating Centre for Tuberculosis and Lung Diseases, Maugeri Care and Research Institute, IRCCS, Tradate, Italy e Public Health Consulting Group, Lugano, Switzerland f Setor de Tuberculose, Laboratório Municipal de Alvorada, Alvorada, Brazil g Microbiologia, Faculdade Factum, Porto Alegre, Brazil h Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil b
A R T I C L E I N F O
A B S T R A C T
Keywords: Tuberculosis Xpert MTB/RIF HIV Diagnosis Brazil
Background and objectives: As for all tests, the diagnostic performances of Xpert MTB/RIF might be different in settings with different tuberculosis prevalence. Aim of the study is to evaluate the performances of Xpert MTB/ RIF to diagnose tuberculosis in Brazil, where 407 culture-confirmed tuberculosis patients were retrospectively enrolled in Rio Grande do Sul, between 2015 and 2016. Methods: Sensitivity, specificity, positive and negative predictive values of the test were calculated and a logistic regression analysis was performed to assess the role played by explanatory variables in the occurrence of true positive and negative diagnostic results. Results: Sensitivity of Xpert MTB/RIF was 100.0%, specificity 92.8%; positive and negative predictive values were 71.4% and 100.0%, respectively. In the HIV- infected sub-group specificity was 59.3%. In the multivariate logistic regression analysis, true positivity was associated with increasing age (1.0; pvalue: 0.02) while true positivity and negativity were negatively associated with alcohol abuse. Conclusions: Xpert is sensitive and specific in the Brasilian settings.
1. Introduction Tuberculosis (TB) is a first-class health priority, with over 10.4 million cases notified in 2015, of whom 480,000 are affected by multidrug-resistant (MDR, defined as disease caused by strains of M. tuberculosis resistant to at least rifampicin and isoniazid) form of disease and additional 100,000 have rifampicin-resistant TB (RR-TB) following diagnosis with Xpert MTB/RIF [1–4]. In Brazil 84,000 TB incident cases were estimated to occur in 2015, with 1900 MDR- and RR TB cases [1,5]. Xpert MTB/RIF has changed the programmatic approach to TB diagnosis, allowing the clinician to know in less than 2 h if his/her case is
affected by TB and if there is resistance to rifampicin (which is considered a proxy for MDR-TB) [6–8]. This is particularly true in high incidence TB countries, where the sensitivity and specificity of the test are high (88% and 98%, respectively) [6,7]. The test was endorsed by World Health Organization (WHO) in 2011 [9–11]. However, the sensitivity of Xpert MTB/RIF is higher in sputum smear positive than in negative cases (98% vs 67%) [6]. The positive and negative predictive values of the test critically depend on the prevalence of TB. The negative predictive value is high, but the positive predictive value can be rather low in low TB incidence countries. In countries where the incidence of TB is intermediate, like in Brazil, information on Xpert MTB/RIF is lacking [12]. Given the potentialities
∗
Corresponding author. Universidade Federal do Rio Grande do Sul, Hospital de Clínicas de Porto Alegre, 2350 Ramiro Barcelos Street, Porto Alegre, Brazil. Corresponding author. World Health Organization Collaborating Centre for Tuberculosis and Lung Diseases, Maugeri Care and Research Institute, IRCCS, Via Roncaccio 16, 21049, Tradate, Italy. E-mail addresses: [email protected] (D.R. Silva), [email protected] (G. Sotgiu), [email protected] (L. D'Ambrosio), [email protected] (G.R. Pereira), [email protected] (M.S. Barbosa), [email protected] (N.J.D. Dias), [email protected] (L. Saderi), [email protected] (R. Centis), [email protected] (G.B. Migliori). 1 Equally contributed. ∗∗
https://doi.org/10.1016/j.rmed.2017.11.012 Received 15 September 2017; Received in revised form 10 October 2017; Accepted 20 November 2017 Available online 21 November 2017 0954-6111/ © 2017 Elsevier Ltd. All rights reserved.
Respiratory Medicine 134 (2018) 12–15
D.R. Silva et al.
of the test to improve TB diagnosis in Brazil, this study was designed to evaluate the diagnostic performances of the test in the HIV- uninfected and – infected patients (sensitivity, specificity, positive and negative predictive values) within the framework of the ERS (European Respiratory Society)/SBPT (Brazilian Society of Respiratory Diseases) collaborative TB project.
Table 1 Demographic, epidemiological, and clinical characteristics of the enrolled cohort. Variables Median (IQR) age, years Male, n (%) White race, n (%) Smoking, n (%)
Non-smoker Former smoker Active smoker Median (IQR) number of cigarettes daily smoked Median (IQR) number of years of smoking habit Median (IQR) number of years of smoking abstinence Cough, n (%) Sputum production, n (%) Weight loss, n (%) Night sweats, n (%) Dyspnoea, n (%) Chest pain, n (%) Fever, n (%) Haemoptysis, n (%) Median (IQR) duration of symptoms, days Previous TB, n (%) Previous default, n (%) Alcohol abuse, n (%) Drug abuse, n (%) Institutionalization (past 3 years), n (%) Comorbidities, n (%) HIV infected, n (%) Acid fast bacilli in the sputum, n (%) Mycobacterium tuberculosis culture positive, n (%) Normal chest X-ray, n (%) Lung cavitations, n (%) Reticular infiltrates, n (%) Lung consolidation, n (%) Lung fibrotic changes, n (%) Miliary pattern, n (%) Resistant to rifampicin, n (%) Xpert MTB/RIF, n (%) Treatment outcome Cure Failure Default Death
2. Material and methods A Brazilian sample of culture-confirmed TB patients was retrospectively enrolled in an outpatient TB clinic located in Alvorada – Rio Grande do Sul, from January 2015 to December 2016. Sampling was consecutive and no specific selection criteria were adopted. Paediatric cases were excluded. An ad-hoc electronic form was built on to collect demographic (e.g., age, gender, ethnicity), epidemiological (e.g., exposure to tobacco smoking, comorbidities, previous TB), clinical (e.g., symptoms, clinical and radiological signs, treatment outcomes), and microbiological (e.g., microscopic, culture, and molecular testing results) variables which could explain the variability of the diagnostic accuracy. Sputum smears were stained by Ziehl-Neelsen (ZN) staining technique for the detection of AFB (alcohol acid fast bacilli), and culture was performed using the Ogawa-Kudoh method. The Xpert MTB/RIF test was performed according to manufacturer's instructions (Cepheid, Sunnyvale, Calif, USA, 2013). In short, clinical sputum samples are treated with a sodium hydroxide and isopropanol-containing sample reagent (SR). The SR is added to the sample and incubated at room temperature for 15 min. This step is designed to reduce the viability of M. tuberculosis in sputum at least 106-fold to reduce biohazard risk. The treated sample is then manually transferred to the cartridge that is preloaded with liquid buffers and lyophilized reagent beads necessary for sample processing, DNA extraction and heminested RT-PCR. Subsequent processing is fully automated. The results are generated automatically on the screen and reported as M. tuberculosis detected or not detected (with semiquantitative estimates of M. tuberculosis concentration reported as low, medium or high) and susceptible or resistant to rifampicin. Categorical and numerical variables were summarized with frequencies (absolute and percentage) and medians (interquartile ranges, IQR), respectively. A logistic regression analysis was performed to assess the role played by explanatory variables in the occurrence of true positive and negative diagnostic results. A statistical significance was considered when two-tailed p-values were less than 0.05. Statistical computations were carried out with the version 13 of the statistical software STATA (StataCorp, College Station, TX, USA).
54 (42–62) 238/407 (58.5) 313/407 (76.9) 44/159 (27.7) 17/159 (10.7) 98/159 (61.6) 20 (20–20) 20 (10–30) 2 (2–5) 398/407 (97.8) 355/407 (87.2) 214/407 (52.6) 101/407 (24.8) 56/407 (13.8) 42/407 (10.3) 71/407 (17.4) 12/407 (3.0) 35 (30–60) 38/159 (23.9) 18/159 (11.3) 57/159 (35.9) 52/159 (32.7) 23/159 (14.5) 247/407 (60.7) 47/407 (11.6) 90/407 (22.1) 75/407 (18.4) 254/407 (62.4) 57/406 (14.0) 62/406 (15.3) 70/406 (17.2) 89/404 (22.0) 9/406 (2.2) 4/407 (1.0) 108/407 (26.5) 112/159 (70.4) 12/159 (7.6) 28/159 (17.6) 7/159 (4.4)
IQR: interquartile range.
with that detected in the HIV- uninfected sub-group. Out of 108 Xpert positive TB cases, 33 (30.6%) were culture negative. All of these Xpert positive/culture negative patients had cough and a chest radiography typical or compatible with TB. Also, 11/33 (33.3%) were HIV infected. In summary, based on clinical/radiological criteria, they were likely to have TB. The multivariate logistic regression analysis found that a true positivity is associated with increasing age (1.0; p-value: 0.02), whereas true positivity and negativity in a multivariate model was negatively associated with alcohol abuse (data not shown).
3. Results A cohort of 407 individuals was recruited; the majority was male (238, 58.5%), white (313/407, 76.9%) with a median (IQR) age of 54 (42–62) years (Table 1). More than 70% of the cases were current or former smokers and less than one quarter (23.9%) had a previous TB episode. The proportion of HIV- infected patients was higher than 10%. More than 60% did not show radiological abnormalities at the chest radiography. Only 1.0% of the patients were resistant to rifampicin. Treatment outcome was described for 159 patients: 70.4% were cured, 17.6% defaulted, 7.6% failed, and 4.4% died. The Xpert MTB/RIF and the culture were performed in all 407 patients. The results in HIV- infected and uninfected patients were described in Table 2. Using culture as the gold standard, the diagnostic performance of the Xpert MTB/RIF in the HIV-negative patients was as follows: sensitivity 100.0%, specificity 92.8%; positive and negative predictive values were 71.4% and 100.0%, respectively. In the HIV- infected subgroup the specificity was significantly lower (59.3%) in comparison
4. Discussion Aim the study was to evaluate the diagnostic performance of the test in the HIV- uninfected and HIV- infected patients in Brazil. In HIV-negative individuals sensitivity and specificity were both very high (100% and 92.8% respectively), consistent with the results by Rachow A et al. [13,14] who described a sensitivity of 98.0% and a specificity of 90.9%. One-third of the cases had positive Xpert and negative culture. Using culture as the gold standard, in HIV- infected patients the specificity was as low as 59.3%, which is difficult to explain. Among the possible reasons, we mention the relatively small sample size and the immunosuppression-related lower sputum smear positivity rate. The results of the multivariate model suggest that the true positivity increases with age. These results are consistent with the findings of 2 existing paediatric studies. In a first study, Sekkade et al. found that age 13
Respiratory Medicine 134 (2018) 12–15
D.R. Silva et al.
Author contributions'
Table 2 Relationship between Xpert MTB/RIF and culture results in HIV- infected and - uninfected subjects. HIV- Infected cases
All authors contributed to the conception and design of the study, drafted the article, revised it critically and finally approved this submitted version.
Culture n (%)
Xpert MTB/RIF
Negative
Positive
Total
Positive Negative Total
11(35.5) 16 (100) 27 (57.4)
20 (64.5) 0 (0) 20 (42.6)
31 16 47
HIV-Negative cases
Culture
Xpert MTB/RIF
Negative
Positive
Total
Positive Negative Total
22 (28.6) 283 (100) 305 (84.7)
55 (71.4) 0 (0) 55 (15.3)
77 283 360
Diagnostic indicator
Sensitivity Specificity Positive predictive value Negative predictive value Positive likelihood ratio Negative likelihood ratio
HIV- infected cases
HIV- uninfected cases
% (95% CI)
% (95% CI)
100.0 (83.2–100.0) 59.3 (38.8–77.6) 64.5 (45.4–80.8) 100.0 (79.4–100.0) 2.5 (1.6–3.9) 0.0 (−)
100.0 (93.5–100.0) 92.8 (89.3–95.4) 71.4 (60.0–81.2) 100.0 (98.7–100.0) 13.9 (9.3–20.7) 0.0 (−)
Conflicts of interest None. Acknowledgements This article has been developed within the ERS (European Respiratory Society)/SBPT (Brazilian Society of Respiratory Diseases) collaborative TB project. References [1] World Health Organization. Global tuberculosis report, WHO/HTM/TB/2016.13 Geneva, World Health Organization, 2016 2016. [2] S.E. Borisov, K. Dheda, M. Enwerem, R. Romero Leyet, L. D'Ambrosio, R. Centis, et al., Effectiveness and safety of bedaquiline containing regimens in the treatment of MDR- and XDR-TB: a multicentre study, Eur. Respir. J. 49 (2017) 1700387 https://doi.org/10.1183/13993003.00387-2017. [3] M. Dalcolmo, R. Gayoso, G. Sotgiu, L. D'Ambrosio, J.L. Rocha, L. Borga, et al., Resistance profile to the drugs composing the ‘shorter’ regimen for multidrug-resistant TB in Brazil, Eur. Respir. J. 2017 (2000-2015) 49 1602309 https://doi.org/ 10.1183/13993003.02309-2016]. [4] M. Dalcolmo, R. Gayoso, G. Sotgiu, L. D'Ambrosio, J.L. Rocha, L. Borga, et al., Effectiveness and safety of clofazimine within a standard multidrug-resistant tuberculosis regimen in Brazil: first nation-wide report on over 2,500 cases, Eur. Respir. J. 49 (3) (2017; Mar 22), http://dx.doi.org/10.1183/13993003.02445-2016 pii: 1602445. [5] V.C. Micheletti, S. Moreira Jda, M.O. Ribeiro, A.L. Kritski, J.U. Braga, Drug-resistant tuberculosis in subjects included in the second national survey on antituberculosis drug resistance in Porto Alegre, Brazil, J. Bras. Pneumol. 40 (2) (2014 Mar-Apr) 155–163. [6] S.D. Lawn, P. Mwaba, M. Bates, A. Piatek, H. Alexander, B.J. Marais, L.E. Cuevas, T.D. McHugh, L. Zijenah, N. Kapata, I. Abubakar, R. McNerney, M. Hoelscher, Z.A. Memish, G.B. Migliori, P. Kim, M. Maeurer, M. Schito, A. Zumla, Advances in tuberculosis diagnostics: the Xpert MTB/RIF assay and future prospects for a pointof-care test, Lancet Infect. Dis. 13 (4) (2013) 349–361, http://dx.doi.org/10.1016/ S1473-3099(13)70008-2. [7] K.R. Steingart, I. Schiller, D.J. Horne, M. Pai, C.C. Boehme, N. Dendukuri, Xpert(R) MTB/RIF assay for pulmonary tuberculosis and rifampicin resistance in adults, Cochrane Database Syst. Rev. 1 (2014), http://dx.doi.org/10.1002/14651858. CD009593.pub3 CD009593. [8] M.A. Telles, A. Menezes, A. Trajman, Bottlenecks and recommendations for the incorporation of new technologies in the tuberculosis laboratory network in Brazil, J. Bras. Pneumol. 38 (6) (2012 Nov-Dec) 766–770. [9] C.C. Boehme, M.P. Nicol, P. Nabeta, J.S. Michael, E. Gotuzzo, R. Tahirli, et al., Feasibility, diagnostic accuracy, and effectiveness of decentralised use of the Xpert MTB/RIF test for diagnosis of tuberculosis and multidrug resistance: a multicentre implementation study, Lancet 377 (9776) (2011 Apr 30) 1495–1505, http://dx.doi. org/10.1016/S0140-6736(11)60438-8. [10] World Health Organization, Xpert MTB/RIF Implementation Manual: Technical and Operational ‘how-to’; Practical Considerations. Document WHO/HTM/TB/2014.1, World Health Organization, Geneva, 2014. [11] K. Weyer, F. Mirzayev, G.B. Migliori, W. Van Gemert, L. D'Ambrosio, M. Zignol, et al., Rapid molecular TB diagnosis: evidence, policy making and global implementation of Xpert MTB/RIF, Eur. Respir. J. 42 (1) (2013) 252–271. [12] M. Pinto, A.P. Entringer, R. Steffen, A. Trajman, Cost analysis of nucleic acid amplification for diagnosing pulmonary tuberculosis, within the context of the Brazilian Unified Health Care System, J. Bras. Pneumol. 41 (6) (2015 Nov-Dec) 536–538. [13] A. Rachow, A. Zumla, N. Heinrich, G. Rojas-Ponce, B. Mtafya, K. Reither, et al., Rapid and accurate detection of Mycobacterium tuberculosis in sputum samples by Cepheid Xpert MTB/RIF assay–a clinical validation study, PLoS One 6 (6) (2011) e20458, http://dx.doi.org/10.1371/journal.pone.0020458. [14] N. Heinrich, A. Rachow, M. Hoelscher, Rapid molecular detection of tuberculosis, N. Engl. J. Med. 364 (2) (2011 Jan 13) 182, http://dx.doi.org/10.1056/ NEJMc1011919#SA1 author reply 184-5. [15] M.P. Sekadde, E. Wobudeya, M.L. Joloba, W. Ssengooba, H. Kisembo, S. BakeeraKitaka, et al., Evaluation of the Xpert MTB/RIF test for the diagnosis of childhood pulmonary tuberculosis in Uganda: a cross-sectional diagnostic study, BMC Infect. Dis. 13 (2013 Mar 12) 133, http://dx.doi.org/10.1186/1471-2334-13-133. [16] Q.Q. Yin, W.W. Jiao, R. Han, A.X. Jiao, L. Sun, J.L. Tian, et al., Rapid diagnosis of childhood pulmonary tuberculosis by Xpert MTB/RIF assay using bronchoalveolar lavage fluid, Biomed. Res. Int. 2014 (2014) 310194, http://dx.doi.org/10.1155/ 2014/310194.
CI: Confidence Interval.
>5 years was associated with a positive Xpert test [15]. In a second study done on children with less than 3 years of age absence of BCG (Bacillus Calmette Guerin) scar and contact with a TB case were associated with a positive test [16]. To our knowledge this is the first study in the literature describing the association between age and positive Xpert test in an adult population, and the first study investigating the performances of the test under programmatic conditions in Brazil. Interestingly, while different studies were able to describe association between alcohol abuse and TB [17–19], we are the first to describe the relationship between alcohol abuse and Xpert performances. In fact, it is known that alcohol consumption (>40 g/day) is responsible of a 13% adult population attributable fraction, being a common habit in the 22 high TB burden countries (although the relative risk for TB is rather low - 2.9) [20]. According to a recent systematic review [19] alcohol consumption is responsible, globally, of 22.02 incidence cases and 2.35 deaths per 100,000 population, which corresponds to about 17% of all incidence cases and death. However, the relationship between alcohol consumption and Xpert positivity has never been previously analysed.
5. Conclusions The study results demonstrate that Xpert is sensitive and specific in countries with an intermediate TB incidence, such as Brazil, and, therefore, its scale-up is important to ensure quality-assured diagnosis and effective treatment, which are core activities to control TB.
Funding source This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
14
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[19] S. Imtiaz, K.D. Shield, M. Roerecke, A.V. Samokhvalov, K. Lönnroth, J. Rehm, Alcohol consumption as a risk factor for tuberculosis: meta-analyses and burden of disease, Eur. Respir. J. 50 (1) (2017), http://dx.doi.org/10.1183/13993003.002162017 pii:1700216. [20] J. Creswell, M.C. Raviglione, S. Ottmani, G.B. Migliori, M. Uplekar, L. Blanc, et al., Tuberculosis and noncommunicable diseases: neglected links and missed opportunities, Eur. Respir. J. 37 (5) (2011) 1269–1282.
[17] S. Hermosilla, P. You, A. Aifah, T. Abildayev, A. Akilzhanova, U. Kozhamkulov, et al., Identifying risk factors associated with smear positivity of pulmonary tuberculosis in Kazakhstan, PLoS One 12 (3) (2017 Mar 1) e0172942, http://dx.doi. org/10.1371/journal.pone.0172942. eCollection 2017. [18] J. Francisco, O. Oliveira, Gaio AR. Felgueiras Ó, R. Duarte, How much is too much alcohol in tuberculosis? Eur. Respir. J. 49 (1) (2017 Jan 18), http://dx.doi.org/10. 1183/13993003.01468-2016 pii: 1601468.
15
Contents lists available at ScienceDirect
Respiratory Medicine journal homepage: www.elsevier.com/locate/rmed
Diagnostic performances of the Xpert MTB/RIF in Brazil a,b,∗,1
c,1
d,e,1
T b,f
Denise Rossato Silva , Giovanni Sotgiu , Lia D'Ambrosio , Giovana Rodrigues Pereira , Márcia Silva Barbosag, Natan José Dutra Diash, Laura Saderic, Rosella Centisd, Giovanni Battista Migliorid,∗∗ a
Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil Programa de Pós-Graduação em Ciências Pneumológicas da UFRGS, Porto Alegre, Brazil c Clinical Epidemiology and Medical Statistics Unit, Department of Biomedical Sciences, University of Sassari, Sassari, Italy d World Health Organization Collaborating Centre for Tuberculosis and Lung Diseases, Maugeri Care and Research Institute, IRCCS, Tradate, Italy e Public Health Consulting Group, Lugano, Switzerland f Setor de Tuberculose, Laboratório Municipal de Alvorada, Alvorada, Brazil g Microbiologia, Faculdade Factum, Porto Alegre, Brazil h Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil b
A R T I C L E I N F O
A B S T R A C T
Keywords: Tuberculosis Xpert MTB/RIF HIV Diagnosis Brazil
Background and objectives: As for all tests, the diagnostic performances of Xpert MTB/RIF might be different in settings with different tuberculosis prevalence. Aim of the study is to evaluate the performances of Xpert MTB/ RIF to diagnose tuberculosis in Brazil, where 407 culture-confirmed tuberculosis patients were retrospectively enrolled in Rio Grande do Sul, between 2015 and 2016. Methods: Sensitivity, specificity, positive and negative predictive values of the test were calculated and a logistic regression analysis was performed to assess the role played by explanatory variables in the occurrence of true positive and negative diagnostic results. Results: Sensitivity of Xpert MTB/RIF was 100.0%, specificity 92.8%; positive and negative predictive values were 71.4% and 100.0%, respectively. In the HIV- infected sub-group specificity was 59.3%. In the multivariate logistic regression analysis, true positivity was associated with increasing age (1.0; pvalue: 0.02) while true positivity and negativity were negatively associated with alcohol abuse. Conclusions: Xpert is sensitive and specific in the Brasilian settings.
1. Introduction Tuberculosis (TB) is a first-class health priority, with over 10.4 million cases notified in 2015, of whom 480,000 are affected by multidrug-resistant (MDR, defined as disease caused by strains of M. tuberculosis resistant to at least rifampicin and isoniazid) form of disease and additional 100,000 have rifampicin-resistant TB (RR-TB) following diagnosis with Xpert MTB/RIF [1–4]. In Brazil 84,000 TB incident cases were estimated to occur in 2015, with 1900 MDR- and RR TB cases [1,5]. Xpert MTB/RIF has changed the programmatic approach to TB diagnosis, allowing the clinician to know in less than 2 h if his/her case is
affected by TB and if there is resistance to rifampicin (which is considered a proxy for MDR-TB) [6–8]. This is particularly true in high incidence TB countries, where the sensitivity and specificity of the test are high (88% and 98%, respectively) [6,7]. The test was endorsed by World Health Organization (WHO) in 2011 [9–11]. However, the sensitivity of Xpert MTB/RIF is higher in sputum smear positive than in negative cases (98% vs 67%) [6]. The positive and negative predictive values of the test critically depend on the prevalence of TB. The negative predictive value is high, but the positive predictive value can be rather low in low TB incidence countries. In countries where the incidence of TB is intermediate, like in Brazil, information on Xpert MTB/RIF is lacking [12]. Given the potentialities
∗
Corresponding author. Universidade Federal do Rio Grande do Sul, Hospital de Clínicas de Porto Alegre, 2350 Ramiro Barcelos Street, Porto Alegre, Brazil. Corresponding author. World Health Organization Collaborating Centre for Tuberculosis and Lung Diseases, Maugeri Care and Research Institute, IRCCS, Via Roncaccio 16, 21049, Tradate, Italy. E-mail addresses: [email protected] (D.R. Silva), [email protected] (G. Sotgiu), [email protected] (L. D'Ambrosio), [email protected] (G.R. Pereira), [email protected] (M.S. Barbosa), [email protected] (N.J.D. Dias), [email protected] (L. Saderi), [email protected] (R. Centis), [email protected] (G.B. Migliori). 1 Equally contributed. ∗∗
https://doi.org/10.1016/j.rmed.2017.11.012 Received 15 September 2017; Received in revised form 10 October 2017; Accepted 20 November 2017 Available online 21 November 2017 0954-6111/ © 2017 Elsevier Ltd. All rights reserved.
Respiratory Medicine 134 (2018) 12–15
D.R. Silva et al.
of the test to improve TB diagnosis in Brazil, this study was designed to evaluate the diagnostic performances of the test in the HIV- uninfected and – infected patients (sensitivity, specificity, positive and negative predictive values) within the framework of the ERS (European Respiratory Society)/SBPT (Brazilian Society of Respiratory Diseases) collaborative TB project.
Table 1 Demographic, epidemiological, and clinical characteristics of the enrolled cohort. Variables Median (IQR) age, years Male, n (%) White race, n (%) Smoking, n (%)
Non-smoker Former smoker Active smoker Median (IQR) number of cigarettes daily smoked Median (IQR) number of years of smoking habit Median (IQR) number of years of smoking abstinence Cough, n (%) Sputum production, n (%) Weight loss, n (%) Night sweats, n (%) Dyspnoea, n (%) Chest pain, n (%) Fever, n (%) Haemoptysis, n (%) Median (IQR) duration of symptoms, days Previous TB, n (%) Previous default, n (%) Alcohol abuse, n (%) Drug abuse, n (%) Institutionalization (past 3 years), n (%) Comorbidities, n (%) HIV infected, n (%) Acid fast bacilli in the sputum, n (%) Mycobacterium tuberculosis culture positive, n (%) Normal chest X-ray, n (%) Lung cavitations, n (%) Reticular infiltrates, n (%) Lung consolidation, n (%) Lung fibrotic changes, n (%) Miliary pattern, n (%) Resistant to rifampicin, n (%) Xpert MTB/RIF, n (%) Treatment outcome Cure Failure Default Death
2. Material and methods A Brazilian sample of culture-confirmed TB patients was retrospectively enrolled in an outpatient TB clinic located in Alvorada – Rio Grande do Sul, from January 2015 to December 2016. Sampling was consecutive and no specific selection criteria were adopted. Paediatric cases were excluded. An ad-hoc electronic form was built on to collect demographic (e.g., age, gender, ethnicity), epidemiological (e.g., exposure to tobacco smoking, comorbidities, previous TB), clinical (e.g., symptoms, clinical and radiological signs, treatment outcomes), and microbiological (e.g., microscopic, culture, and molecular testing results) variables which could explain the variability of the diagnostic accuracy. Sputum smears were stained by Ziehl-Neelsen (ZN) staining technique for the detection of AFB (alcohol acid fast bacilli), and culture was performed using the Ogawa-Kudoh method. The Xpert MTB/RIF test was performed according to manufacturer's instructions (Cepheid, Sunnyvale, Calif, USA, 2013). In short, clinical sputum samples are treated with a sodium hydroxide and isopropanol-containing sample reagent (SR). The SR is added to the sample and incubated at room temperature for 15 min. This step is designed to reduce the viability of M. tuberculosis in sputum at least 106-fold to reduce biohazard risk. The treated sample is then manually transferred to the cartridge that is preloaded with liquid buffers and lyophilized reagent beads necessary for sample processing, DNA extraction and heminested RT-PCR. Subsequent processing is fully automated. The results are generated automatically on the screen and reported as M. tuberculosis detected or not detected (with semiquantitative estimates of M. tuberculosis concentration reported as low, medium or high) and susceptible or resistant to rifampicin. Categorical and numerical variables were summarized with frequencies (absolute and percentage) and medians (interquartile ranges, IQR), respectively. A logistic regression analysis was performed to assess the role played by explanatory variables in the occurrence of true positive and negative diagnostic results. A statistical significance was considered when two-tailed p-values were less than 0.05. Statistical computations were carried out with the version 13 of the statistical software STATA (StataCorp, College Station, TX, USA).
54 (42–62) 238/407 (58.5) 313/407 (76.9) 44/159 (27.7) 17/159 (10.7) 98/159 (61.6) 20 (20–20) 20 (10–30) 2 (2–5) 398/407 (97.8) 355/407 (87.2) 214/407 (52.6) 101/407 (24.8) 56/407 (13.8) 42/407 (10.3) 71/407 (17.4) 12/407 (3.0) 35 (30–60) 38/159 (23.9) 18/159 (11.3) 57/159 (35.9) 52/159 (32.7) 23/159 (14.5) 247/407 (60.7) 47/407 (11.6) 90/407 (22.1) 75/407 (18.4) 254/407 (62.4) 57/406 (14.0) 62/406 (15.3) 70/406 (17.2) 89/404 (22.0) 9/406 (2.2) 4/407 (1.0) 108/407 (26.5) 112/159 (70.4) 12/159 (7.6) 28/159 (17.6) 7/159 (4.4)
IQR: interquartile range.
with that detected in the HIV- uninfected sub-group. Out of 108 Xpert positive TB cases, 33 (30.6%) were culture negative. All of these Xpert positive/culture negative patients had cough and a chest radiography typical or compatible with TB. Also, 11/33 (33.3%) were HIV infected. In summary, based on clinical/radiological criteria, they were likely to have TB. The multivariate logistic regression analysis found that a true positivity is associated with increasing age (1.0; p-value: 0.02), whereas true positivity and negativity in a multivariate model was negatively associated with alcohol abuse (data not shown).
3. Results A cohort of 407 individuals was recruited; the majority was male (238, 58.5%), white (313/407, 76.9%) with a median (IQR) age of 54 (42–62) years (Table 1). More than 70% of the cases were current or former smokers and less than one quarter (23.9%) had a previous TB episode. The proportion of HIV- infected patients was higher than 10%. More than 60% did not show radiological abnormalities at the chest radiography. Only 1.0% of the patients were resistant to rifampicin. Treatment outcome was described for 159 patients: 70.4% were cured, 17.6% defaulted, 7.6% failed, and 4.4% died. The Xpert MTB/RIF and the culture were performed in all 407 patients. The results in HIV- infected and uninfected patients were described in Table 2. Using culture as the gold standard, the diagnostic performance of the Xpert MTB/RIF in the HIV-negative patients was as follows: sensitivity 100.0%, specificity 92.8%; positive and negative predictive values were 71.4% and 100.0%, respectively. In the HIV- infected subgroup the specificity was significantly lower (59.3%) in comparison
4. Discussion Aim the study was to evaluate the diagnostic performance of the test in the HIV- uninfected and HIV- infected patients in Brazil. In HIV-negative individuals sensitivity and specificity were both very high (100% and 92.8% respectively), consistent with the results by Rachow A et al. [13,14] who described a sensitivity of 98.0% and a specificity of 90.9%. One-third of the cases had positive Xpert and negative culture. Using culture as the gold standard, in HIV- infected patients the specificity was as low as 59.3%, which is difficult to explain. Among the possible reasons, we mention the relatively small sample size and the immunosuppression-related lower sputum smear positivity rate. The results of the multivariate model suggest that the true positivity increases with age. These results are consistent with the findings of 2 existing paediatric studies. In a first study, Sekkade et al. found that age 13
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Author contributions'
Table 2 Relationship between Xpert MTB/RIF and culture results in HIV- infected and - uninfected subjects. HIV- Infected cases
All authors contributed to the conception and design of the study, drafted the article, revised it critically and finally approved this submitted version.
Culture n (%)
Xpert MTB/RIF
Negative
Positive
Total
Positive Negative Total
11(35.5) 16 (100) 27 (57.4)
20 (64.5) 0 (0) 20 (42.6)
31 16 47
HIV-Negative cases
Culture
Xpert MTB/RIF
Negative
Positive
Total
Positive Negative Total
22 (28.6) 283 (100) 305 (84.7)
55 (71.4) 0 (0) 55 (15.3)
77 283 360
Diagnostic indicator
Sensitivity Specificity Positive predictive value Negative predictive value Positive likelihood ratio Negative likelihood ratio
HIV- infected cases
HIV- uninfected cases
% (95% CI)
% (95% CI)
100.0 (83.2–100.0) 59.3 (38.8–77.6) 64.5 (45.4–80.8) 100.0 (79.4–100.0) 2.5 (1.6–3.9) 0.0 (−)
100.0 (93.5–100.0) 92.8 (89.3–95.4) 71.4 (60.0–81.2) 100.0 (98.7–100.0) 13.9 (9.3–20.7) 0.0 (−)
Conflicts of interest None. Acknowledgements This article has been developed within the ERS (European Respiratory Society)/SBPT (Brazilian Society of Respiratory Diseases) collaborative TB project. References [1] World Health Organization. Global tuberculosis report, WHO/HTM/TB/2016.13 Geneva, World Health Organization, 2016 2016. [2] S.E. Borisov, K. Dheda, M. Enwerem, R. Romero Leyet, L. D'Ambrosio, R. Centis, et al., Effectiveness and safety of bedaquiline containing regimens in the treatment of MDR- and XDR-TB: a multicentre study, Eur. Respir. J. 49 (2017) 1700387 https://doi.org/10.1183/13993003.00387-2017. [3] M. Dalcolmo, R. Gayoso, G. Sotgiu, L. D'Ambrosio, J.L. Rocha, L. Borga, et al., Resistance profile to the drugs composing the ‘shorter’ regimen for multidrug-resistant TB in Brazil, Eur. Respir. J. 2017 (2000-2015) 49 1602309 https://doi.org/ 10.1183/13993003.02309-2016]. [4] M. Dalcolmo, R. Gayoso, G. Sotgiu, L. D'Ambrosio, J.L. Rocha, L. Borga, et al., Effectiveness and safety of clofazimine within a standard multidrug-resistant tuberculosis regimen in Brazil: first nation-wide report on over 2,500 cases, Eur. Respir. J. 49 (3) (2017; Mar 22), http://dx.doi.org/10.1183/13993003.02445-2016 pii: 1602445. [5] V.C. Micheletti, S. Moreira Jda, M.O. Ribeiro, A.L. Kritski, J.U. Braga, Drug-resistant tuberculosis in subjects included in the second national survey on antituberculosis drug resistance in Porto Alegre, Brazil, J. Bras. Pneumol. 40 (2) (2014 Mar-Apr) 155–163. [6] S.D. Lawn, P. Mwaba, M. Bates, A. Piatek, H. Alexander, B.J. Marais, L.E. Cuevas, T.D. McHugh, L. Zijenah, N. Kapata, I. Abubakar, R. McNerney, M. Hoelscher, Z.A. Memish, G.B. Migliori, P. Kim, M. Maeurer, M. Schito, A. Zumla, Advances in tuberculosis diagnostics: the Xpert MTB/RIF assay and future prospects for a pointof-care test, Lancet Infect. Dis. 13 (4) (2013) 349–361, http://dx.doi.org/10.1016/ S1473-3099(13)70008-2. [7] K.R. Steingart, I. Schiller, D.J. Horne, M. Pai, C.C. Boehme, N. Dendukuri, Xpert(R) MTB/RIF assay for pulmonary tuberculosis and rifampicin resistance in adults, Cochrane Database Syst. Rev. 1 (2014), http://dx.doi.org/10.1002/14651858. CD009593.pub3 CD009593. [8] M.A. Telles, A. Menezes, A. Trajman, Bottlenecks and recommendations for the incorporation of new technologies in the tuberculosis laboratory network in Brazil, J. Bras. Pneumol. 38 (6) (2012 Nov-Dec) 766–770. [9] C.C. Boehme, M.P. Nicol, P. Nabeta, J.S. Michael, E. Gotuzzo, R. Tahirli, et al., Feasibility, diagnostic accuracy, and effectiveness of decentralised use of the Xpert MTB/RIF test for diagnosis of tuberculosis and multidrug resistance: a multicentre implementation study, Lancet 377 (9776) (2011 Apr 30) 1495–1505, http://dx.doi. org/10.1016/S0140-6736(11)60438-8. [10] World Health Organization, Xpert MTB/RIF Implementation Manual: Technical and Operational ‘how-to’; Practical Considerations. Document WHO/HTM/TB/2014.1, World Health Organization, Geneva, 2014. [11] K. Weyer, F. Mirzayev, G.B. Migliori, W. Van Gemert, L. D'Ambrosio, M. Zignol, et al., Rapid molecular TB diagnosis: evidence, policy making and global implementation of Xpert MTB/RIF, Eur. Respir. J. 42 (1) (2013) 252–271. [12] M. Pinto, A.P. Entringer, R. Steffen, A. Trajman, Cost analysis of nucleic acid amplification for diagnosing pulmonary tuberculosis, within the context of the Brazilian Unified Health Care System, J. Bras. Pneumol. 41 (6) (2015 Nov-Dec) 536–538. [13] A. Rachow, A. Zumla, N. Heinrich, G. Rojas-Ponce, B. Mtafya, K. Reither, et al., Rapid and accurate detection of Mycobacterium tuberculosis in sputum samples by Cepheid Xpert MTB/RIF assay–a clinical validation study, PLoS One 6 (6) (2011) e20458, http://dx.doi.org/10.1371/journal.pone.0020458. [14] N. Heinrich, A. Rachow, M. Hoelscher, Rapid molecular detection of tuberculosis, N. Engl. J. Med. 364 (2) (2011 Jan 13) 182, http://dx.doi.org/10.1056/ NEJMc1011919#SA1 author reply 184-5. [15] M.P. Sekadde, E. Wobudeya, M.L. Joloba, W. Ssengooba, H. Kisembo, S. BakeeraKitaka, et al., Evaluation of the Xpert MTB/RIF test for the diagnosis of childhood pulmonary tuberculosis in Uganda: a cross-sectional diagnostic study, BMC Infect. Dis. 13 (2013 Mar 12) 133, http://dx.doi.org/10.1186/1471-2334-13-133. [16] Q.Q. Yin, W.W. Jiao, R. Han, A.X. Jiao, L. Sun, J.L. Tian, et al., Rapid diagnosis of childhood pulmonary tuberculosis by Xpert MTB/RIF assay using bronchoalveolar lavage fluid, Biomed. Res. Int. 2014 (2014) 310194, http://dx.doi.org/10.1155/ 2014/310194.
CI: Confidence Interval.
>5 years was associated with a positive Xpert test [15]. In a second study done on children with less than 3 years of age absence of BCG (Bacillus Calmette Guerin) scar and contact with a TB case were associated with a positive test [16]. To our knowledge this is the first study in the literature describing the association between age and positive Xpert test in an adult population, and the first study investigating the performances of the test under programmatic conditions in Brazil. Interestingly, while different studies were able to describe association between alcohol abuse and TB [17–19], we are the first to describe the relationship between alcohol abuse and Xpert performances. In fact, it is known that alcohol consumption (>40 g/day) is responsible of a 13% adult population attributable fraction, being a common habit in the 22 high TB burden countries (although the relative risk for TB is rather low - 2.9) [20]. According to a recent systematic review [19] alcohol consumption is responsible, globally, of 22.02 incidence cases and 2.35 deaths per 100,000 population, which corresponds to about 17% of all incidence cases and death. However, the relationship between alcohol consumption and Xpert positivity has never been previously analysed.
5. Conclusions The study results demonstrate that Xpert is sensitive and specific in countries with an intermediate TB incidence, such as Brazil, and, therefore, its scale-up is important to ensure quality-assured diagnosis and effective treatment, which are core activities to control TB.
Funding source This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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[19] S. Imtiaz, K.D. Shield, M. Roerecke, A.V. Samokhvalov, K. Lönnroth, J. Rehm, Alcohol consumption as a risk factor for tuberculosis: meta-analyses and burden of disease, Eur. Respir. J. 50 (1) (2017), http://dx.doi.org/10.1183/13993003.002162017 pii:1700216. [20] J. Creswell, M.C. Raviglione, S. Ottmani, G.B. Migliori, M. Uplekar, L. Blanc, et al., Tuberculosis and noncommunicable diseases: neglected links and missed opportunities, Eur. Respir. J. 37 (5) (2011) 1269–1282.
[17] S. Hermosilla, P. You, A. Aifah, T. Abildayev, A. Akilzhanova, U. Kozhamkulov, et al., Identifying risk factors associated with smear positivity of pulmonary tuberculosis in Kazakhstan, PLoS One 12 (3) (2017 Mar 1) e0172942, http://dx.doi. org/10.1371/journal.pone.0172942. eCollection 2017. [18] J. Francisco, O. Oliveira, Gaio AR. Felgueiras Ó, R. Duarte, How much is too much alcohol in tuberculosis? Eur. Respir. J. 49 (1) (2017 Jan 18), http://dx.doi.org/10. 1183/13993003.01468-2016 pii: 1601468.
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