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Research Article

Predictors and Prevalence of Latent Tuberculosis Infection in Patients Receiving Long-Term Hemodialysis and Peritoneal Dialysis

  • Chin-Chung Shu,

    Affiliations: Department of Traumatology, National Taiwan University Hospital, Taipei City, Taiwan, College of Internal Medicine, National Taiwan University, Taipei City, Taiwan

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  • Vin-Cent Wu,

    Affiliations: College of Internal Medicine, National Taiwan University, Taipei City, Taiwan, Department of Internal Medicine, National Taiwan University Hospital, Taipei City, Taiwan

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  • Feng-Jung Yang,

    Affiliation: Department of Internal Medicine, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin County, Taiwan

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  • Sung-Ching Pan,

    Affiliation: Department of Internal Medicine, National Taiwan University Hospital, Taipei City, Taiwan

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  • Tai-Shuan Lai,

    Affiliation: Department of Internal Medicine, National Taiwan University Hospital, Bei-Hu Branch, Taipei City, Taiwan

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  • Jann-Yuan Wang mail,

    jywang@ntu.edu.tw

    Affiliations: College of Internal Medicine, National Taiwan University, Taipei City, Taiwan, Department of Internal Medicine, National Taiwan University Hospital, Taipei City, Taiwan

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  • Jann-Tay Wang,

    Affiliations: College of Internal Medicine, National Taiwan University, Taipei City, Taiwan, Department of Internal Medicine, National Taiwan University Hospital, Taipei City, Taiwan

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  • Li-Na Lee

    Affiliation: Department of Laboratory Medicine, National Taiwan University Hospital, Taipei City, Taiwan

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  • Published: August 20, 2012
  • DOI: 10.1371/journal.pone.0042592

Abstract

Background

Tuberculosis is a common infectious disease in long-term dialysis patients. The prevalence of latent tuberculosis infection (LTBI) in this population is unclear, particularly in those receiving peritoneal dialysis (PD). This study investigated the prevalence of LTBI in patients receiving either hemodialysis (HD) or PD to determine predictors of LTBI and indeterminate results of interferon-gamma release assay.

Methods

Patients receiving long-term (≥3 months) HD or PD from March 2011 to February 2012 in two medical centers were prospectively enrolled. QuantiFERON-Gold in tube (QFT) test was used to determine the status of LTBI after excluding active tuberculosis. The LTBI prevalence was determined in patients receiving different dialysis modes to obtain predictors of LTBI and QFT-indeterminate results.

Results

Of 427 patients enrolled (124 PD and 303 HD), 91 (21.3%) were QFT-positive, 316 (74.0%) QFT-negative, and 20 (4.7%) QFT-indeterminate. The prevalence of LTBI was similar in the PD and HD groups. Independent predictors of LTBI were old age (OR: 1.034 [1.013–1.056] per year increment), TB history (OR: 6.467 [1.985–21.066]), and current smoker (OR: 2.675 [1.061–6.747]). Factors associated with indeterminate QFT results were HD (OR: 10.535 [1.336–83.093]), dialysis duration (OR: 1.113 [1.015–1.221] per year increment), anemia (OR: 8.760 [1.014–75.651]), and serum albumin level (OR: 0.244 [0.086–0.693] per 1 g/dL increment).

Conclusion

More than one-fifth of dialysis patients have LTBI. The LTBI prevalence is similar in PD and HD patients but is higher in the elderly, current smokers, and those with prior TB history. Such patients require closer follow-up. Repeated or alternative test may be required for malnutrition patients who received long length of HD.

Introduction

Tuberculosis (TB) remains a worldwide infectious disease with high mortality. Control involves preventing further TB transmission via early diagnosis and treatment of latent TB infection (LTBI) [1]. Dialysis patients are at increased risk of tuberculosis (TB) due to attenuated cellular immunity [2]. Compared to the general population, their risk of developing active TB is 7.8–25 times higher [3][5] and their mortality rate due to TB is also higher [4][7]. Moreover, TB diagnosis in dialysis patients is usually delayed because of frequent extra-pulmonary manifestations [8], [9]. Early LTBI detection and monitoring of the development of active TB in this specific group are therefore important [1]. Currently, interferon-gamma release assays (IGRAs) used to determine LTBI cases, though not 100% accurate, have been proven useful even in immuno-compromised hosts and Bacille Calmette Guérin (BCG)-vaccinated subjects [10][12]. For patients receiving hemodialysis, the IGRA-positive rate is reportedly around 21–40% [13][15], while 6–11% of patients have indeterminate IGRA results [14][17]. However, studies focusing on patients receiving peritoneal dialysis (PD) are lacking.

Traditionally, HD patients are believed to have higher prevalence of LTBI than PD patients due to more frequent hospital visits and longer hospital stay [14]. In fact, studies supporting this argument are lacking. Understanding the predictors for LTBI and indeterminate IGRA results in the dialysis population is important in policy-making to determine the priority groups for IGRA screening [18], [19]. This cross sectional study was conducted to analyze the prevalence of LTBI in patients receiving long-term HD and PD, and to examine the predictors for LTBI and indeterminate IGRA results.

Methods

This cross sectional study was conducted at National Taiwan University Hospital, a tertiary referral center in northern Taiwan, and its branch in southern Taiwan. The hospital's institutional review board approved the study. From March 2011 to February 2012, adult patients (age ≥20 years) receiving long-term (>3 months) dialysis were prospectively identified. All participants provided written informed consent. Chest radiography and clinical history were obtained to exclude active TB disease. Acid-fast smear and mycobacterial culture for three sputum samples were performed as previously described if TB was suspected [20]. Those with human immunodeficiency virus infection, liver cirrhosis of Child-Pugh class C [21], cancer or autoimmune disease receiving chemotherapy within the last three months, life expectancy of less than 6 months, and active TB within the last three years were excluded.

Peripheral blood samples were taken to detect LTBI using QuantiFERON-TB Gold In-Tube assay (QFT) (Celestis, Australia), which was performed according to the manufacturer's instructions [22]. Interferon-gamma level of the post-reaction supernatant was then measured by enzyme-linked immuno-sorbent assay (ELISA) and results were interpreted as positive, negative, or indeterminate accordingly [23], [24]. In this study, LTBI was defined as a positive QFT result.

Data collection

Demographic and clinical data, including age, sex, underlying co-morbidities, prior TB history, contact history of TB, respiratory and constitutional symptoms, smoking status, and blood hemoglobin and serum albumin levels were recorded in a standardized case report form. Dialysis mode was defined as its use in the past three months prior to the QFT test. Every session of HD regularly lasted for 4 hours according to the National Kidney Foundation Kidney Disease Outcome Quality Initiative (NKF KDOQI) [25], with two-to-three sessions per week depending on the patient's residual renal function and the adequacy of dialysis. Peritoneal dialysis was recorded as continuous ambulatory peritoneal dialysis (CAPD) or automated peritoneal dialysis (APD). Hypoalbuminemia was defined as serum albumin level <3.5 g/dL [26] and anemia as hemoglobin level <12 g/dL in males and <11 g/dL in females. Cough ≥3 weeks was defined as chronic cough. Current smoker was defined as those who had smoked >100 cigarettes, with the latest time of smoking within one month prior to the study [27].

Chest radiography findings were classified into “no lung parenchymal lesion”; “lung lesion not compatible with TB”; or “lung lesion compatible with prior TB”. The lung lesion compatible with TB was defined as new patch(es) of consolidation, collapse, lymphadenopathy, mass or nodule, or cavitary lesion without other proven etiology [5]. Prior TB was defined radiographically as fibrotic infiltrates with pleural thickening or calcified nodules over the upper lung fields and other fibrotic lesions documented from previous TB disease [28].

Statistical analysis

Subjects were classified according to LTBI status for further comparison. Inter-group differences were analyzed using the student t test for numerical variables and chi-square test for categorical variables. Multivariate logistic regression analysis was used to identify factors associated with LTBI and QFT-indeterminate results. All potential predictors were included in the stepwise variable selection procedure. A two-sided p<0.05 was considered significant. All analyses were performed using the SPSS (Version 13.0, Chicago, IL).

Results

A total of 427 subjects (mean age, 61.1±13.1 years; male, 53%) with long-term dialysis (mean length of dialysis use, 4.8±4.2 years) were enrolled, including 303 HD patients and 124 PD patients (Table 1). Among HD patients, 271 (89.4%) had three sessions per week while the remaining 32 (10.6%) had two sessions per week. Among PD patients, 81 (65.3%) had CAPD and 43 (34.7%) had APD.

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Table 1. Clinical characteristics of patients with different modes of dialysis.

doi:10.1371/journal.pone.0042592.t001

Compared to HD patients, PD patients were significantly younger, predominantly female, more symptomatic with chronic cough, had shorter length of dialysis duration, had lower serum albumin level, and were less likely to have pulmonary lesions on chest radiograph (18% vs. 37%; p<0.001). The proportion of QFT-positive patients was similar in the two groups (19% vs. 22%, p = 0.109).

The QFT result was positive in 91 (21.3%) patients, negative in 316 (74.0%), and indeterminate in the remaining 20 (4.7%) (Table 2). Among the 20 QFT-indeterminate results, 19 were due to weak response to mitogen and one due to strong response of negative control. The QFT tests were repeated in 14 of the 20 patients and were negative in 9, positive in 1, and indeterminate in the remaining 4.

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Table 2. Clinical characteristics of patients with different QuantiFERON-TB test (QFT) results.

doi:10.1371/journal.pone.0042592.t002

Compared to combined group of QFT- positive and QFT-negative patients, the 20 QFT-indeterminate patients were older and less likely to be ex-smokers, received HD for a longer period, and had more dyspnea and constitutional symptoms (Table 2). They also had lower serum albumin level and a higher proportion of patients with pulmonary lesions. Multivariate logistic regression analysis revealed that dialysis duration (Odds Ratio [O.R.] 1.113, 95% C.I. 1.015–1.221 per year increment), HD (O.R. 10.535, 95% C.I. 1.336–83.093), anemia (O.R. 8.760, 95% C.I. 1.014–75.651), and serum albumin level (O.R. 0.244, 95% C.I. 0.086–0.693 per unit increment) were significant predictors of QFT-indeterminate results (Table 3). If 3.5 g/dl was used as cut-off value for serum albumin level to predict an indeterminate QFT result, sensitivity and specificity were 80% and 93%, respectively.

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Table 3. Multivariate logistic regression for indeterminate results of QuantiFERON-TB test.

doi:10.1371/journal.pone.0042592.t003

Patients with LTBI (QFT-positive) were older and more likely had a prior TB history compared to QFT-negative patients, by univariate analysis (Table 2). In multivariate logistic regression analysis, independent predictors of LTBI included age (O.R. 1.034, 95% C.I. 1.013–1.056, per year increment), prior TB history (O.R. 6.467, 95% C.I. 1.985–21.066), and current smoker (O.R. 6.467, 95% C.I. 1.985–21.066) (Table 4; Figure 1). The presence of underlying co-morbidity was not an independent predictor. In patients with prior TB history and those who were current smokers, the prevalence of LTBI was 57.1% and 29.6%, respectively. This prevalence increased by <15% in patients younger than 50 years old to almost 30% in those older than 80 years old.

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Figure 1. The proportion of latent tuberculosis infection (LTBI) cases defined by QuantiFERON-TB test was plotted according to age, smoking status, and history of TB.

doi:10.1371/journal.pone.0042592.g001
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Table 4. Multivariate logistic regression for latent tuberculosis (TB) infection diagnosed by QuantiFERON-TB test.

doi:10.1371/journal.pone.0042592.t004

Discussion

This is the first cross sectional study that investigated the prevalence of LTBI in a large number of patients receiving either long-term PD or HD. Using QFT as a diagnostic tool for LTBI in this immuno-compromised population, 4.7% may have an indeterminate result, especially those with anemia, hypoalbuminemia, and who have been receiving HD for a long time. There is a high prevalence (21.3%) of LTBI in the long-term dialysis population, especially in the elderly, current smokers, and those with prior TB history. However, the use of either PD or HD is associated with similar risks of LTBI.

Though IGRA-positive is not 100% equivalent of LTBI, it has several advantages over tuberculin skin test (TST) in terms of convenience and accuracy [10][12]. The TST has a significant limitation in Taiwan due to BCG vaccination [29] and the high prevalence of NTM disease [30]. In QFT, by incorporating positive control (mitogen) and negative control (no antigen) tubes, the true immune reaction against Mycobacterium tuberculosis-specific antigens can be differentiated from false-positive result due to non-specific activation and false-negative result due to immuno-suppression. Thus, IGRA is a better screening test for LTBI than TST while implementing public health policy, especially for an immune-compromised host.

Previous studies using IGRA report an LTBI prevalence of 21–40% in HD patients [13][15]. The QFT-positive rate in the present study is within this range and lower than 40%, as reported in a study conducted in south Taiwan [14]. This is probably because the incidence of TB has been decreasing in Taiwan [31]. However, the prevalence in the present study (21.3%) is similar to that reported in household contacts in large-scale studies (11~30%) [12], [32] and much higher than the results of new health-care staff in the study institute at the same period (13 [5.7%] QFT-positive in 229 [unpublished data]). As such, it can be posited that dialysis patients in Taiwan have a much higher prevalence of LTBI than the general population and should be a priority group for targeted screening for active TB disease, especially IGRA-positive patients. If IGRA is unavailable, focus should be on older patients, current smokers, and those with prior TB history. Quite interestingly, the three predictors for LTBI identified in the present study are also risk factors of active TB disease [14], [33], [34]. Different combinations of these predictors may be useful to select the target population for preventive therapy for LTBI. However, the cost and benefit of preventive therapy in this special population should be further evaluated.

The population of chronic renal failure patients receiving long-term dialysis is increasing worldwide and TB is a commonly associated infectious disease [18], [19]. It has been previously assumed that because HD patients frequently visit the HD room, they are more likely to acquire Mycobacterium tuberculosis infection than PD patients via airborne transmission. Only a report of PD patients in Spain has shown a comparable LTBI prevalence of 18% [35]. By simultaneously enrolling HD and PD patients, this is the first study to demonstrate similar LTBI prevalence in the two patient groups, thereby challenging the hypothesis of occult transmission in the HD room. Although the two dialysis groups are different in more ways than just dialysis place and duration, this observation suggests that transmission of TB to HD patients within crowded dialysis facilities may be similar to PD patients at home [36]. This suggests that the study institute has an effective TB infection control policy on early detection, prompt treatment, and rapid isolation.

Although 71.4% of QFT-indeterminate patients have definite results after repeat testing, 4.7% of the initial QFT tests with an indeterminate result are associated with hypoalbuminemia, anemia, HD, and longer dialysis duration. The association between anemia and indeterminate status has been shown before [37]. Along with hypoalbuminemia, these predictors suggest that malnutrition attenuates immune response and compromises the performance of IGRA [38]. The current finding that HD, but not PD, is associated with QFT-indeterminate is interesting and worth discussing further. A previous study reveals that while both HD and PD patients have lower but insignificant HLD-DR expression on peripheral blood monocytes compared to healthy controls, HLA-DR expression is significantly higher in PD than in HD patients [39]. This implies that continuous dialysis like PD can attenuate immune dysfunction compared to intermittent modes like HD. Moreover, longer duration of dialysis in dialysis patients has been correlated with worse cellular immunity [40]. This may explain how a much higher percentage (95%) of QFT-indeterminate results in the present study may come from low mitogen responses, compared to 51% in a public health clinic setting [24]. For diagnosing LTBI in such patients, IGRA should be meticulously applied. Repeating IGRA or using alternative tests may be necessary.

In contrast to a previous report [24], female gender is not an independent factor of QFT-indeterminate results in the present study. This may be due to different patient characteristics, such as age, race, and prevalence of HIV infection, between studies. Further large-scale investigations are necessary to confirm this finding and investigate possible reasons.

The present study has several limitations. First, this study was conducted in a tertiary referral center and its branch, so patients had more underlying co-morbidities and the LTBI prevalence might be higher. Second, without detailed contact investigation, the epidemiologic link and biological implication of QFT-positivity cannot be confirmed. Lastly, this is a cross-sectional study. Further prospective studies with long-term follow-up on the development of active TB are needed.

In conclusion, patients receiving PD have a similar prevalence of LTBI as those receiving HD (19% and 22%, respectively). The prevalence of LTBI in long-term dialysis patients is even higher in the elderly, current smokers, and those with prior TB history. These risk factors can be used to select a target group for cost-effective LTBI screening. Patients receiving HD or long duration of dialysis, and those with anemia or lower albumin level are likely to have a QFT-indeterminate result. For such patients, repeat IGRA or alternative test may be necessary to detect LTBI.

Disclosures

Parts of the study results have been presented as a poster in the 2011 Congress of the Asia Pacific Society of Respirology and the 2012 International Conference of the American Thoracic Society.

Author Contributions

Conceived and designed the experiments: LNL JYW CCS. Performed the experiments: CCS FJY SCP TSL JTW VCW. Analyzed the data: JYW CCS. Wrote the paper: JYW VCW CCS.

References

  1. 1. Rose DN (2000) Benefits of screening for latent Mycobacterium tuberculosis infection. Arch Intern Med 160: 1513–1521. doi: 10.1001/archinte.160.10.1513
  2. 2. Christopoulos AI, Diamantopoulos AA, Dimopoulos PA, Gumenos DS, Barbalias GA (2006) Risk of tuberculosis in dialysis patients: association of tuberculin and 2,4-dinitrochlorobenzene reactivity with risk of tuberculosis. Int Urol Nephrol 38: 745–751. doi: 10.1007/s11255-006-9051-3
  3. 3. Dobler CC, McDonald SP, Marks GB (2011) Risk of tuberculosis in dialysis patients: a nationwide cohort study. PLoS One 6: e29563. doi: 10.1371/journal.pone.0029563
  4. 4. Lundin AP, Adler AJ, Berlyne GM, Friedman EA (1979) Tuberculosis in patients undergoing maintenance hemodialysis. Am J Med 67: 597–602. doi: 10.1016/0002-9343(79)90240-7
  5. 5. Smirnoff M, Patt C, Seckler B, Adler JJ (1998) Tuberculin and anergy skin testing of patients receiving long-term hemodialysis. Chest 113: 25–27. doi: 10.1378/chest.113.1.25
  6. 6. Jick SS, Lieberman ES, Rahman MU, Choi HK (2006) Glucocorticoid use, other associated factors, and the risk of tuberculosis. Arthritis Rheum 55: 19–26. doi: 10.1002/art.21705
  7. 7. Targeted tuberculin testing and treatment of latent tuberculosis infection. American Thoracic Society. MMWR Recomm Rep 49: 1–51.
  8. 8. Venkata RK, Kumar S, Krishna RP, Kumar SB, Padmanabhan S (2007) Tuberculosis in chronic kidney disease. Clin Nephrol 67: 217–220. doi: 10.5414/CNP67217
  9. 9. Fang HC, Lee PT, Chen CL, Wu MJ, Chou KJ, et al. (2004) Tuberculosis in patients with end-stage renal disease. Int J Tuberc Lung Dis 8: 92–97.
  10. 10. Simsek H, Alpar S, Ucar N, Aksu F, Ceyhan I, et al. (2010) Comparison of tuberculin skin testing and T-SPOT.TB for diagnosis of latent and active tuberculosis. Jpn J Infect Dis 63: 99–102.
  11. 11. Brock I, Weldingh K, Lillebaek T, Follmann F, Andersen P (2004) Comparison of tuberculin skin test and new specific blood test in tuberculosis contacts. Am J Respir Crit Care Med 170: 65–69. doi: 10.1164/rccm.200402-232OC
  12. 12. Diel R, Loddenkemper R, Meywald-Walter K, Niemann S, Nienhaus A (2008) Predictive value of a whole blood IFN-gamma assay for the development of active tuberculosis disease after recent infection with Mycobacterium tuberculosis. Am J Respir Crit Care Med 177: 1164–1170. doi: 10.1164/rccm.200711-1613OC
  13. 13. Triverio PA, Bridevaux PO, Roux-Lombard P, Niksic L, Rochat T, et al. (2009) Interferon-gamma release assays versus tuberculin skin testing for detection of latent tuberculosis in chronic haemodialysis patients. Nephrol Dial Transplant 24: 1952–1956. doi: 10.1093/ndt/gfn748
  14. 14. Lee SS, Chou KJ, Su IJ, Chen YS, Fang HC, et al. (2009) High prevalence of latent tuberculosis infection in patients in end-stage renal disease on hemodialysis: Comparison of QuantiFERON-TB GOLD, ELISPOT, and tuberculin skin test. Infection 37: 96–102. doi: 10.1007/s15010-008-8082-3
  15. 15. Lee SS, Chou KJ, Dou HY, Huang TS, Ni YY, et al. (2010) High prevalence of latent tuberculosis infection in dialysis patients using the interferon-gamma release assay and tuberculin skin test. Clin J Am Soc Nephrol 5: 1451–1457. doi: 10.2215/CJN.01790210
  16. 16. Chung WK, Zheng ZL, Sung JY, Kim S, Lee HH, et al. (2010) Validity of interferon-gamma-release assays for the diagnosis of latent tuberculosis in haemodialysis patients. Clin Microbiol Infect 16: 960–965. doi: 10.1111/j.1469-0691.2009.02949.x
  17. 17. Sester M, Sester U, Clauer P, Heine G, Mack U, et al. (2004) Tuberculin skin testing underestimates a high prevalence of latent tuberculosis infection in hemodialysis patients. Kidney Int 65: 1826–1834. doi: 10.1111/j.1523-1755.2004.00586.x
  18. 18. Stevens LA, Viswanathan G, Weiner DE (2010) Chronic kidney disease and end-stage renal disease in the elderly population: current prevalence, future projections, and clinical significance. Adv Chronic Kidney Dis 17: 293–301. doi: 10.1053/j.ackd.2010.03.010
  19. 19. Hill CJ, Fogarty DG (2012) Changing trends in end-stage renal disease due to diabetes in the United kingdom. J Ren Care 38 Suppl 1: 12–22. doi: 10.1111/j.1755-6686.2012.00273.x
  20. 20. Shu CC, Wang JT, Lee CH, Wang JY, Lee LN, et al. (2010) Predicting results of mycobacterial culture on sputum smear reversion after anti-tuberculous treatment: a case control study. BMC Infect Dis 10: 48. doi: 10.1186/1471-2334-10-48
  21. 21. Pugh RN, Murray-Lyon IM, Dawson JL, Pietroni MC, Williams R (1973) Transection of the oesophagus for bleeding oesophageal varices. Br J Surg 60: 646–649. doi: 10.1002/bjs.1800600817
  22. 22. Lalvani A, Pathan AA, McShane H, Wilkinson RJ, Latif M, et al. (2001) Rapid detection of Mycobacterium tuberculosis infection by enumeration of antigen-specific T cells. Am J Respir Crit Care Med 163: 824–828. doi: 10.1164/ajrccm.163.4.2009100
  23. 23. Dyrhol-Riise AM, Gran G, Wentzel-Larsen T, Blomberg B, Haanshuus CG, et al. (2010) Diagnosis and follow-up of treatment of latent tuberculosis; the utility of the QuantiFERON-TB Gold In-tube assay in outpatients from a tuberculosis low-endemic country. BMC Infect Dis 10: 57. doi: 10.1186/1471-2334-10-57
  24. 24. Banach DB, Harris TG (2011) Indeterminate QuantiFERON(R)-TB Gold results in a public health clinic setting. Int J Tuberc Lung Dis 15: 1623–1630. doi: 10.5588/ijtld.11.0017
  25. 25. NKF-DOQI clinical practice guidelines for hemodialysis adequacy. National Kidney Foundation. Am J Kidney Dis 30: S15–66.
  26. 26. Lukowsky LR, Kheifets L, Arah OA, Nissenson AR, Kalantar-Zadeh K (2012) Patterns and Predictors of Early Mortality in Incident Hemodialysis Patients: New Insights. Am J Nephrol 35: 548–558. doi: 10.1159/000338673
  27. 27. Lin HH, Ezzati M, Chang HY, Murray M (2009) Association between tobacco smoking and active tuberculosis in Taiwan: prospective cohort study. Am J Respir Crit Care Med 180: 475–480. doi: 10.1164/rccm.200904-0549OC
  28. 28. Jasmer RM, Snyder DC, Chin DP, Hopewell PC, Cuthbert SS, et al. (2000) Twelve months of isoniazid compared with four months of isoniazid and rifampin for persons with radiographic evidence of previous tuberculosis: an outcome and cost-effectiveness analysis. Am J Respir Crit Care Med 162: 1648–1652. doi: 10.1164/ajrccm.162.5.2003028
  29. 29. Yu MC, Suo J, Huang C, Bai KJ, Lin TP, et al. (1999) Annual risk of tuberculous infection in Taiwan, 1996–1998. J Formos Med Assoc 98: 496–499.
  30. 30. Lai CC, Tan CK, Chou CH, Hsu HL, Liao CH, et al. (2010) Increasing incidence of nontuberculous mycobacteria, Taiwan, 2000–2008. Emerg Infect Dis 16: 294–296. doi: 10.3201/eid1602.090675
  31. 31. Centers of Disease Control DoH, R.O.C. (Taiwan) (2010) CDC Annual Report 2011. Taipei: Centers of Disease Control, Department of Health, R.O.C. (Taiwan).
  32. 32. Wang JY, Shu CC, Lee CH, Yu CJ, Lee LN, et al. (2012) Interferon-gamma release assay and Rifampicin therapy for household contacts of tuberculosis. J Infect 64: 291–298. doi: 10.1016/j.jinf.2011.11.028
  33. 33. Shu CC, Wu HD, Yu MC, Wang JT, Lee CH, et al. (2010) Use of high-dose inhaled corticosteroids is associated with pulmonary tuberculosis in patients with chronic obstructive pulmonary disease. Medicine (Baltimore) 89: 53–61. doi: 10.1097/MD.0b013e3181cafcd3
  34. 34. Bates MN, Khalakdina A, Pai M, Chang L, Lessa F, et al. (2007) Risk of tuberculosis from exposure to tobacco smoke: a systematic review and meta-analysis. Arch Intern Med 167: 335–342. doi: 10.1001/archinte.167.4.335
  35. 35. Palomar R, Arias Guillen M, Robledo C, Aguero R, Aguero J, et al. (2011) Detection of latent tuberculosis infection in peritoneal dialysis patients: new methods. Nefrologia 31: 169–173. doi: 10.3265/Nefrologia.pre2011.Jan.10765
  36. 36. Chavers BM, Solid CA, Gilbertson DT, Collins AJ (2007) Infection-related hospitalization rates in pediatric versus adult patients with end-stage renal disease in the United States. J Am Soc Nephrol 18: 952–959. doi: 10.1681/ASN.2006040406
  37. 37. Lange B, Vavra M, Kern WV, Wagner D (2010) Indeterminate results of a tuberculosis-specific interferon-gamma release assay in immunocompromised patients. Eur Respir J 35: 1179–1182. doi: 10.1183/09031936.00122109
  38. 38. Fabrizi F, Dixit V, Martin P, Jadoul M, Messa P (2011) Meta-Analysis: The Impact of Nutritional Status on the Immune Response to Hepatitis B Virus Vaccine in Chronic Kidney Disease. Dig Dis Sci 2012; 57: 1366–1372. doi: 10.1007/s10620-011-1987-1
  39. 39. de Cal M, Cruz DN, Corradi V, Nalesso F, Polanco N, et al. (2008) HLA-DR expression and apoptosis: a cross-sectional controlled study in hemodialysis and peritoneal dialysis patients. Blood Purif 26: 249–254. doi: 10.1159/000122110
  40. 40. Vacher-Coponat H, Brunet C, Lyonnet L, Bonnet E, Loundou A, et al. (2008) Natural killer cell alterations correlate with loss of renal function and dialysis duration in uraemic patients. Nephrol Dial Transplant 23: 1406–1414. doi: 10.1093/ndt/gfm596