- Email: [email protected]
First Epidemiologic Study in Argentina of the Prevalence of BK Viruria in Kidney Transplant Patients
First Epidemiologic Study in Argentina of the Prevalence of BK Viruria in Kidney Transplant Patients R. Schiavellia,*, R. Bonaventurab, M.C. Rialc, H. Petroned, G. Soler Pujole, L.J. Gaitef, M. Acostag, A. Gutierrezg, F. Acostah, G. Valdezi, P. Raffaelej, G. Chantaa, M. Perezk, L. Potesk, E. Susol, G. Cremadesl, J. Ibañezm, N. Imperialin, R. Luxardon, M. Castellanoso, E. Maggiorap, C. Agost Carreñoq, M. Cobosr, K. Marinics, J.L. Sinchis, A.B. Oterot, and M.C. Freireb a Unidad de Nefrología y Trasplante Renal, Hospital Argerich, CABA, Argentina; bServicio de Neurovirosis, INEI-ANLIS “C.G.Malbrán”, CABA, Argentina; cNephrology, CABA, Argentina; dCRAI Sur, Provincia de BA, Argentina; eCEMIC, CABA, Argentina; fClínica de Nefrología, Urología y Enfermedades Cardiovasculares, Santa Fe, Argentina; gClínica La Entrerriana, Entre Rios, Argentina; hHospital Provincial Centenario, Rosario, Argentina; iCRAI Norte, Provincia de Buenos Aires, Argentina; jFundación Favaloro, CABA, Argentina; k Hospital de la Comunidad, Mar del Plata, Argentina; lHospital Español de Mendoza, Mendoza, Argentina; mHospital Garrahan, CABA, Argentina; nHospital Italiano Bs.As., CABA, Argentina; oHospital Privado de Córdoba, Cordoba, Argentina; pSanatorio Anchorena; q Sanatorio Mitre, CABA, Argentina; rHospital Español de la Plata, La Plata, Argentina; sHospital Perrando, Chaco, Argentina; and t Novartis Argentina SA
ABSTRACT Background. The worldwide seroprevalence of human BK polyomavirus (BKV) in adults is 80%. About 10%e60% of renal transplant recipients experience BKV infection, nephropathy of the graft may occur in 5% of the cases, and up to 45% lose the graft. The aim of this work was to describe the prevalence of BK viruria during the 1st year after transplantation. Methods. An epidemiologic multicenter cross-sectional study was carried out in consecutive patients at each site with kidney transplantation from August 2011 to July 2012. Clinically significant viruria was defined as >107 copies/mL. Viral DNA was extracted with the use of silica columns. Quantification was performed with the use of real-time polymerase chain reaction with primers that amplify a fragment of the large T-antigen gene and with a specific Taqman-MGB probe for BKV. For each assay, a standard curve with a quantified plasmid was included. Results. Of 402 renal transplant recipients at 18 renal transplant sites, we analyzed 382; median age was 46.33 years, and 46.40% were female. The median of the temporal distribution for urine samples was 153 days. BK virus was detected in 50/382 samples (13%), 18 with values >107 copies/mL (4.7%). The median of the distribution of positive values was 123 days and the highest frequency of positive values was in months 3e7. The conditions of recipient older than 34 years and donor older than 41 years were the only ones that showed statistically significant association with BK viruria. No association with any specific immunosuppressive drug was observed. Conclusions. This is the first multicenter study conducted in Argentina to determine the prevalence of BK viruria in renal transplant recipients. Because of the growing number of the population susceptible to this infection, it is important to register and describe data about its epidemiology and associated risk factors.
T
HE WORLDWIDE seroprevalence of human BK polyomavirus (BKV) in adults is 80%. The primary infection is asymptomatic and occurs during childhood. After entering the body, the virus remains latent, mainly in
The first 2 authors contributed equally to this work. Funding: grant from Novartis Argentina. *Address correspondence to R. Schiavelli, Alte Brown 240, CABA, CP 1155, Argentina. E-mail: [email protected]
0041-1345/14 http://dx.doi.org/10.1016/j.transproceed.2014.07.009
ª 2014 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
3010
Transplantation Proceedings, 46, 3010e3014 (2014)
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Table 1. Baseline Recipient and Donor Data % or Median
Recipients Female (%) Age (y) CMV positivity (%) HCV positivity (%) HBsAg positivity (%) Chagas positivity (%) Dialysis after transplantation (%) Creatinine at the time of sampling (mg/dL) Urine sample (days after transplantation) Donors Alive (%) Female (%) Age (y) EB positivity in alive patients (%) CMV positivity (%) HCV positivity (%) HBsAg positivity (%) Chagas positivity (%)
46.4 46.33 87.46 5.86 1.60 3.46 55.91 1.84 154
19 45.43 42.92 21.67 42.55 4.17 1.56 1.04
95% CI
d 44.47e48.19 d d d d d 1.71e1.97 153e175
d d 41.35e44.49 d d d d d
Abbreviations: CI, confidence interval; CMV, cytomegalovirus; HCV, hepatitis C virus; HBsAg, hepatitis B surface antigen.
the urinary tract. Reactivation may occur in individuals with compromised cellular immunity [1e3]. About 10%e60% of renal transplant recipients show BKV infection, and as a result, nephropathy of the graft may occur in 5% of the cases and up to 45% may lose their organ. Therefore, early diagnosis allows the treatment of positive cases [4e7]. It is important to consider that no specific antiviral therapy is available for the treatment of this infection, although the use of cidofovir or lefluonamide has been shown to be
effective in some cases; also, reduction of immunosuppression is generally implemented [8e10]. Because viruria always precede viremia, the determination of the urinary viral load is very useful. Additionally, it is very important to determine the presence of the virus in the blood as well as its quantification so that a more certain diagnosis can be made and the prognosis of the patient can be established. If viruria is >107 copies/mL or viremia >104 copies/mL and these values are maintained for >3 weeks, this is indicative of BKV-associated nephropathy (BKVAN) and should be confirmed with a biopsy [10e12]. In general, screening for BKV is recommended in renal transplant recipients during the 1st 2 years following the intervention, although most BKVAN cases occur during the 1st year after transplantation. Kidney Disease Improving Global Outcomes guidelines recommend monthly assessment of the urinary viral load during the first 3e6 months and then quarterly during the 1st year after transplantation or when unexplained creatinine increases or rejection occur [13]. Given the current costs of this determination, routine surveillance following these periods of time is not a common practice. In 2012, almost 75% of transplantations performed in Argentina were kidney transplantations. Considering these data and the increasing number of renal transplantations year after year, there is a growing population susceptible to symptomatic BKV infection. Because the prevalence of viruria, viremia, and BKVAN in Argentina is not known, the present study was proposed with the primary objective of describing the prevalence of clinically significant viruria (>107 copies/mL) in renal transplant recipients during the 1st year after transplantation and the identification of the factors associated with such positivity.
Fig 1. Temporal distribution of urinary sampling during the recruitment year.
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SCHIAVELLI, BONAVENTURA, RIAL ET AL
Fig 2. Temporal distribution of urinary sampling positive for BK virus (any viral load value).
METHODS An epidemiologic multicenter, initially cross-sectional, study was carried out in consecutive patients receiving kidney transplants from August 2011 to July 2012. For this screening, the determination of viruria was selected because it is the most sensitive diagnostic test for the detection of active BKV infection [4]. Patient data recording and the results of viruria were performed with the use of an electronic clinical record form with direct online access with the use of a personal and unique access password for each participating site. The sample size required was 350 patients, calculated for an estimated BKVAN prevalence of 5% and considering that, most probably, those patients suffering from the condition have a urinary viral load >107 copies/mL [14]. Only 1 random urine sample was collected from each participating patient. Patients were consecutively enrolled by site. All 402 patients enrolled provided consent for sample and data collection. The operators were blinded to the identity of patients. Viral DNA was extracted with the use of the Qiamp viral RNA extraction kit according to the manufacturer’s protocol (Qiagen, Hilden, Germany). Quantification was performed with the use of real-time polymerase chain reaction technique with
primers, PM2þ and PM2, that amplify a conserved 103-bp fragment of the large T-antigen gene and a specific Taqman-MGB probe (Applied Biosystems) for BKV labeled with carboxyfluorescein [15]. For each assay, a standard curve from 102 to 1010 copies was constructed with a previously quantified plasmid. All study and control sample were evaluated in duplicate. Results were listed and analyzed with the use of descriptive statistics tools, and association measures (odds ratio [OR]) were also applied to identify the risk factors associated with positive viruria.
RESULTS
A total of 402 renal transplant recipients were recruited in 18 renal transplant sites in the provinces of Buenos Aires (La Plata, Mar del Plata, and Gran Buenos Aires), Santa Fe, Mendoza, Entre Ríos, Córdoba, Chaco, and Ciudad Autónoma de Buenos Aires. The final analysis was performed with 382 patients (patients eliminated were cases where the urine sample had been obtained outside the perprotocol period of time), 46.40% were female, the median
Fig 3. Temporal distribution of urinary sampling positive for BK virus (viral load >107copies/mL).
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Table 2. Univariate Analysis of Results for Patients With Viruria (>107 copies/mL) Characteristic
Positivity
Characteristic
Positivity
Deceased donor CMVþ donor CMVþ recipient HCVþ donor HCVþ recipient Dialysis after transplantation: yes Recipient <34 y Donor <41 y Presence of rejection Creatinine <1.22 mg/dL Induction: yes Cyclosporine: yes Tacrolimus: yes mTORi: yes Mismatch <3
16/302 11/292 15/328 0/3 2/22 10/175 1/103 4/147 0/51 7/210 14/291 3/46 12/279 2/51 6/101
Alive donor CMV donor CMV recipient HCV donor HCV recipient Dialysis after transplantation: no Recipient 34 years Donor 41 years Absence of rejection Creatinine 1.22 mg/dL Induction: no Cyclosporine: no Tacrolimus no mTORi: no Mismatch 3
2/79 2/56 1/38 13/341 14/344 5/138 17/277 10/84 18/331 7/164 4/88 15/336 6/103 16/313 7/151
OR (95% CI)
2.14 1.05 1.77 12.61 2.35 1.61 0.14 0.20 0.00 0.80 1.06 1.46 0.76 0.80 1.29
(4.53) (1.53) (2.05) (2.41) (1.54) (1.09) (2.09) (1.19) (0) (1.06) (1.13) (2.30) (1.13) (1.82) (1.12)
P Value (Fisher)
.24 .29 .32 .11 .18 .15 .02 .0054 .08 .20 .22 .38 .59 .55 .77
Note. Because data were sometimes incomplete for each variable, the total sum of cases in each comparison may not reach 382 analyzed cases; therefore, the number of cases considered for each characteristic is reported in the numerator. The ORs for azathioprine (0/11) and mycophenolate (18/352) were not calculated. Abbreviations: OR, odds ratio; mTORi, inhibitor of mammalian target of rapamycin; other abbreviations as in Table 1.
age of the group was 46.33 years, the age range was 4e79 years, and the number of pediatric patients included was 20, in which the prevalence of BKV positivity was 0%. The baseline characteristics of the group of patients recruited are listed in Table 1. In general, the tabulated data correspond to the usual distribution of renal transplant recipients in Argentina, where annually w1,200 renal patients undergo transplantation, 81% of them being recipients from deceased donors (data from the National Information System; https://cresi.incucai.gov.ar/reporte/resumenestadistico/ EjecutarConsultaTx.do). The median of the temporal distribution for urine samples was 153 days, ranging from 1 to 396 days (Fig 1). Sample reception was accepted with a deviation up to 1 month with respect to the year. The presence of BKV was detected in 50/382 samples (13%), 18 of which showing values greater than 107 copies/mL (4.7%). The median of the distribution of positive values was 123 days (21e304 days), the highest concentration being observed in months 3e7 after transplantation (Figs 2 and 3). Univariate analyses were performed in patients with positive results in urine determinations (>107 copies/mL) for each possible risk factor and showed that the risk for developing viruria greater than the cutoff value was increased only for the conditions of being a recipient older than 34 years and a donor older than 41 years, with a statistically significant association between the risk factor and the result (Table 2). The immunosuppressive regimens included induction in 286 (75%) patients: antithymocyte globulin in 195 patients, anti-CD25 in 73 patients, and antilymphocyte globulin in 18 patients. The use of calcineurin inhibitors included tacrolimus in 279 patients and cyclosporine in 46 patients; 352 patients received mycophenolate as a coimmunosuppressive agent, 11 azathioprine, and 51 patients a proliferation signal
inhibitor (sirolimus or everolimus). No association between the type of immunosuppression and the presence of viruria was observed (Table 2). Considering the almost universal use of mycophenolatedalways in association with another immunosuppressive agentdthe ORs for azathioprine (0/11) and mycophenolate (18/352) were not calculated. DISCUSSION
This was the first epidemiologic cross-sectional study carried out in Argentina to evaluate the prevalence of BK viruria (>107 copies/mL) in renal transplant recipients during the 1st year after transplantation. The population under study showed the typical characteristics of the general population of kidney transplant recipients in Argentina. Furthermore, as a result of the number of patients included in the analysis (382), the number of sites participating (18), and the estimated prevalence of the condition under study (5%), we consider that the patients evaluated in this sample were significantly representative of the kidney transplant population in Argentina. The prevalence observed for an degree of BK viruria was 50/382 (13%). This figure is in accord with, though in the lowest end of the range, the international literature, which reports values of 10%e60% [4]. Although the prevalence observed for BK viruria >107 copies/mL was 4.7%, and these patients are at increased risk for developing BKVAN, that could not be confirmed in any case during the time of this cross-sectional analysis. In addition to the prevalence of BK viruria, this study analyzed the association between several risk factors previously described for BKVAN in the international literature [16], considering the presence of BK viruria >107 copies/mL to be a surrogate marker of nephropathy [17,18]. The analysis was not able to associate typically identified factors with the presence of viruria >107 copies/mL, but it showed a statistically significant increased risk for 2
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characteristics: donors older than 41 years and recipients older than 34 years. The lack of association between BKVAN and the traditional risk factors has been described by Sood et al [19]. This was the first multicenter study conducted in Argentina to determine the prevalence of BK viruria in renal transplant recipients. Because of the growing number of the population susceptible to this infection, it is important that accurate information regarding the situation in our country be available. REFERENCES [1] Lin PL, Vats AN, Green. BK virus infection in renal transplant recipients. Pediatr Transplant 2001;5:398e405. [2] de Caprio JA, Imperiale MJ, Major EO. Polyomavirus. In: Knipe DM, Howley PM, Cohen JI, et al., editors. Fields’ virology. 6th ed. Philadelphia: Lippincott Williams; 2013. pp. 1633e61. [3] Priftakis P. Studies on Human polyomavirus infection in immunosuppressed patients and in patients with polyoma related tumors [thesis]. Division of Experimental Oncology, Department of Oncology-Pathology, Cancer Center Karolinska, Karolinska Institute, Stockholm, Sweden; 2001. p 9e24. [4] Hirsch HH, Brennan D, Drachenberg CB, et al. Polyomavirusassociated nephropathy in renal transplantation: interdisciplinary analyses and recommendations. Transplantation 2005;10:1277e86. [5] Nickeleit V, Hirsch HH, Binet IF, et al. Polyomavirus infection of renal allograft recipients: from latent infection to manifest disease. J Am Soc Nephrol 1999;10:1080e9. [6] Nickeleit V, Hirsch HH, Zeiler M, et al. BK-virus nephropathy in renal transplants-tubular necrosis, MHC-class II expression and rejection in a puzzling game. Nephrol Dial Transplant 2000;15: 324e32. [7] Randhawa PS, Demetris AJ. Nephropathy due to polyomavirus type BK. N Engl J Med 2000;342:1361e3. [8] Schaub S, Hirsch HH, Dickenmann M, et al. Reducing immunosuppression preserves allograft function in presumptive and
SCHIAVELLI, BONAVENTURA, RIAL ET AL definitive polyomavirus-associated nephropathy. Am J Transplant 2010;10:2615e23. [9] Herman J, van Ranst M, Snoeck R, et al. Polyomavirus infection in pediatric renal transplant recipients: evaluation using a quantitative real-time PCR technique. Pediatr Transplant 2004;8:485e92. [10] Vats A, Shapiro R, Randhawa P, et al. Quantitative viral load monitoring and cidofovir therapy for the management of BK viruseassociated nephropathy in children and adults. Transplantation 2003;75:105e12. [11] Hirsch HH. BK virus: opportunity makes a pathogen. Clin Infect Dis 2005;41:354e60. [12] Weinstein L, Swartz MN. Pathogenic properties of invading micro-organisms. In: Sodeman Jr WA, Sodeman WA, editors. Pathologic physiology: mechanisms of disease. Philadelphia: Saunders; 1974. pp. 457e72. [13] Kasiske BL, Zeier MG, Chapman JR, et al. KDIGO clinical practice guideline for the care of kidney transplant recipients: a summary. Kidney Int 2010;77:299e311. [14] Naing L, Winn T, Rusli BN. Practical issues in calculating the sample size for prevalence studies. Arch Orofac Sci 2006;1: 9e14. [15] Bárcena-Panero A, Echevarría JE, Romero-Gómez MP, et al. Development and validation with clinical samples of internally controlled multiplex real-time PCR for diagnosis of BKV and JCV infection in associated pathologies. Comp Immunol Microbiol Infect Dis 2012;35:173e9. [16] Hirsch HH. BK virus replication and disease in solid organ transplant recipients: an update. Curr Opin Organ Transpl 2003;8: 262e8. [17] Dharnidharka VR, Cherikh WS, Abbott KC. An OPTN analysis of national registry data on treatment of BK virus allograft nephropathy in the United States. Transplantation 2009; 87:1019e26. [18] Hirsch HH, Vincenti F, Friman S, et al. Polyomavirus BK replication in de novo kidney transplant patients receiving tacrolimus or cyclosporine: a prospective, randomized, multicenter study. Am J Transplant 2013;13:136e45. [19] Sood P, Senanayake S, Sujeet K, et al. Lower prevalence of BK virus infection in African American renal transplant recipients: a prospective study. Transplantation 2012;93:291e6.
ABSTRACT Background. The worldwide seroprevalence of human BK polyomavirus (BKV) in adults is 80%. About 10%e60% of renal transplant recipients experience BKV infection, nephropathy of the graft may occur in 5% of the cases, and up to 45% lose the graft. The aim of this work was to describe the prevalence of BK viruria during the 1st year after transplantation. Methods. An epidemiologic multicenter cross-sectional study was carried out in consecutive patients at each site with kidney transplantation from August 2011 to July 2012. Clinically significant viruria was defined as >107 copies/mL. Viral DNA was extracted with the use of silica columns. Quantification was performed with the use of real-time polymerase chain reaction with primers that amplify a fragment of the large T-antigen gene and with a specific Taqman-MGB probe for BKV. For each assay, a standard curve with a quantified plasmid was included. Results. Of 402 renal transplant recipients at 18 renal transplant sites, we analyzed 382; median age was 46.33 years, and 46.40% were female. The median of the temporal distribution for urine samples was 153 days. BK virus was detected in 50/382 samples (13%), 18 with values >107 copies/mL (4.7%). The median of the distribution of positive values was 123 days and the highest frequency of positive values was in months 3e7. The conditions of recipient older than 34 years and donor older than 41 years were the only ones that showed statistically significant association with BK viruria. No association with any specific immunosuppressive drug was observed. Conclusions. This is the first multicenter study conducted in Argentina to determine the prevalence of BK viruria in renal transplant recipients. Because of the growing number of the population susceptible to this infection, it is important to register and describe data about its epidemiology and associated risk factors.
T
HE WORLDWIDE seroprevalence of human BK polyomavirus (BKV) in adults is 80%. The primary infection is asymptomatic and occurs during childhood. After entering the body, the virus remains latent, mainly in
The first 2 authors contributed equally to this work. Funding: grant from Novartis Argentina. *Address correspondence to R. Schiavelli, Alte Brown 240, CABA, CP 1155, Argentina. E-mail: [email protected]
0041-1345/14 http://dx.doi.org/10.1016/j.transproceed.2014.07.009
ª 2014 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
3010
Transplantation Proceedings, 46, 3010e3014 (2014)
BK-VIRUS IN KIDNEY TRANSPLANTATION
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Table 1. Baseline Recipient and Donor Data % or Median
Recipients Female (%) Age (y) CMV positivity (%) HCV positivity (%) HBsAg positivity (%) Chagas positivity (%) Dialysis after transplantation (%) Creatinine at the time of sampling (mg/dL) Urine sample (days after transplantation) Donors Alive (%) Female (%) Age (y) EB positivity in alive patients (%) CMV positivity (%) HCV positivity (%) HBsAg positivity (%) Chagas positivity (%)
46.4 46.33 87.46 5.86 1.60 3.46 55.91 1.84 154
19 45.43 42.92 21.67 42.55 4.17 1.56 1.04
95% CI
d 44.47e48.19 d d d d d 1.71e1.97 153e175
d d 41.35e44.49 d d d d d
Abbreviations: CI, confidence interval; CMV, cytomegalovirus; HCV, hepatitis C virus; HBsAg, hepatitis B surface antigen.
the urinary tract. Reactivation may occur in individuals with compromised cellular immunity [1e3]. About 10%e60% of renal transplant recipients show BKV infection, and as a result, nephropathy of the graft may occur in 5% of the cases and up to 45% may lose their organ. Therefore, early diagnosis allows the treatment of positive cases [4e7]. It is important to consider that no specific antiviral therapy is available for the treatment of this infection, although the use of cidofovir or lefluonamide has been shown to be
effective in some cases; also, reduction of immunosuppression is generally implemented [8e10]. Because viruria always precede viremia, the determination of the urinary viral load is very useful. Additionally, it is very important to determine the presence of the virus in the blood as well as its quantification so that a more certain diagnosis can be made and the prognosis of the patient can be established. If viruria is >107 copies/mL or viremia >104 copies/mL and these values are maintained for >3 weeks, this is indicative of BKV-associated nephropathy (BKVAN) and should be confirmed with a biopsy [10e12]. In general, screening for BKV is recommended in renal transplant recipients during the 1st 2 years following the intervention, although most BKVAN cases occur during the 1st year after transplantation. Kidney Disease Improving Global Outcomes guidelines recommend monthly assessment of the urinary viral load during the first 3e6 months and then quarterly during the 1st year after transplantation or when unexplained creatinine increases or rejection occur [13]. Given the current costs of this determination, routine surveillance following these periods of time is not a common practice. In 2012, almost 75% of transplantations performed in Argentina were kidney transplantations. Considering these data and the increasing number of renal transplantations year after year, there is a growing population susceptible to symptomatic BKV infection. Because the prevalence of viruria, viremia, and BKVAN in Argentina is not known, the present study was proposed with the primary objective of describing the prevalence of clinically significant viruria (>107 copies/mL) in renal transplant recipients during the 1st year after transplantation and the identification of the factors associated with such positivity.
Fig 1. Temporal distribution of urinary sampling during the recruitment year.
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SCHIAVELLI, BONAVENTURA, RIAL ET AL
Fig 2. Temporal distribution of urinary sampling positive for BK virus (any viral load value).
METHODS An epidemiologic multicenter, initially cross-sectional, study was carried out in consecutive patients receiving kidney transplants from August 2011 to July 2012. For this screening, the determination of viruria was selected because it is the most sensitive diagnostic test for the detection of active BKV infection [4]. Patient data recording and the results of viruria were performed with the use of an electronic clinical record form with direct online access with the use of a personal and unique access password for each participating site. The sample size required was 350 patients, calculated for an estimated BKVAN prevalence of 5% and considering that, most probably, those patients suffering from the condition have a urinary viral load >107 copies/mL [14]. Only 1 random urine sample was collected from each participating patient. Patients were consecutively enrolled by site. All 402 patients enrolled provided consent for sample and data collection. The operators were blinded to the identity of patients. Viral DNA was extracted with the use of the Qiamp viral RNA extraction kit according to the manufacturer’s protocol (Qiagen, Hilden, Germany). Quantification was performed with the use of real-time polymerase chain reaction technique with
primers, PM2þ and PM2, that amplify a conserved 103-bp fragment of the large T-antigen gene and a specific Taqman-MGB probe (Applied Biosystems) for BKV labeled with carboxyfluorescein [15]. For each assay, a standard curve from 102 to 1010 copies was constructed with a previously quantified plasmid. All study and control sample were evaluated in duplicate. Results were listed and analyzed with the use of descriptive statistics tools, and association measures (odds ratio [OR]) were also applied to identify the risk factors associated with positive viruria.
RESULTS
A total of 402 renal transplant recipients were recruited in 18 renal transplant sites in the provinces of Buenos Aires (La Plata, Mar del Plata, and Gran Buenos Aires), Santa Fe, Mendoza, Entre Ríos, Córdoba, Chaco, and Ciudad Autónoma de Buenos Aires. The final analysis was performed with 382 patients (patients eliminated were cases where the urine sample had been obtained outside the perprotocol period of time), 46.40% were female, the median
Fig 3. Temporal distribution of urinary sampling positive for BK virus (viral load >107copies/mL).
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Table 2. Univariate Analysis of Results for Patients With Viruria (>107 copies/mL) Characteristic
Positivity
Characteristic
Positivity
Deceased donor CMVþ donor CMVþ recipient HCVþ donor HCVþ recipient Dialysis after transplantation: yes Recipient <34 y Donor <41 y Presence of rejection Creatinine <1.22 mg/dL Induction: yes Cyclosporine: yes Tacrolimus: yes mTORi: yes Mismatch <3
16/302 11/292 15/328 0/3 2/22 10/175 1/103 4/147 0/51 7/210 14/291 3/46 12/279 2/51 6/101
Alive donor CMV donor CMV recipient HCV donor HCV recipient Dialysis after transplantation: no Recipient 34 years Donor 41 years Absence of rejection Creatinine 1.22 mg/dL Induction: no Cyclosporine: no Tacrolimus no mTORi: no Mismatch 3
2/79 2/56 1/38 13/341 14/344 5/138 17/277 10/84 18/331 7/164 4/88 15/336 6/103 16/313 7/151
OR (95% CI)
2.14 1.05 1.77 12.61 2.35 1.61 0.14 0.20 0.00 0.80 1.06 1.46 0.76 0.80 1.29
(4.53) (1.53) (2.05) (2.41) (1.54) (1.09) (2.09) (1.19) (0) (1.06) (1.13) (2.30) (1.13) (1.82) (1.12)
P Value (Fisher)
.24 .29 .32 .11 .18 .15 .02 .0054 .08 .20 .22 .38 .59 .55 .77
Note. Because data were sometimes incomplete for each variable, the total sum of cases in each comparison may not reach 382 analyzed cases; therefore, the number of cases considered for each characteristic is reported in the numerator. The ORs for azathioprine (0/11) and mycophenolate (18/352) were not calculated. Abbreviations: OR, odds ratio; mTORi, inhibitor of mammalian target of rapamycin; other abbreviations as in Table 1.
age of the group was 46.33 years, the age range was 4e79 years, and the number of pediatric patients included was 20, in which the prevalence of BKV positivity was 0%. The baseline characteristics of the group of patients recruited are listed in Table 1. In general, the tabulated data correspond to the usual distribution of renal transplant recipients in Argentina, where annually w1,200 renal patients undergo transplantation, 81% of them being recipients from deceased donors (data from the National Information System; https://cresi.incucai.gov.ar/reporte/resumenestadistico/ EjecutarConsultaTx.do). The median of the temporal distribution for urine samples was 153 days, ranging from 1 to 396 days (Fig 1). Sample reception was accepted with a deviation up to 1 month with respect to the year. The presence of BKV was detected in 50/382 samples (13%), 18 of which showing values greater than 107 copies/mL (4.7%). The median of the distribution of positive values was 123 days (21e304 days), the highest concentration being observed in months 3e7 after transplantation (Figs 2 and 3). Univariate analyses were performed in patients with positive results in urine determinations (>107 copies/mL) for each possible risk factor and showed that the risk for developing viruria greater than the cutoff value was increased only for the conditions of being a recipient older than 34 years and a donor older than 41 years, with a statistically significant association between the risk factor and the result (Table 2). The immunosuppressive regimens included induction in 286 (75%) patients: antithymocyte globulin in 195 patients, anti-CD25 in 73 patients, and antilymphocyte globulin in 18 patients. The use of calcineurin inhibitors included tacrolimus in 279 patients and cyclosporine in 46 patients; 352 patients received mycophenolate as a coimmunosuppressive agent, 11 azathioprine, and 51 patients a proliferation signal
inhibitor (sirolimus or everolimus). No association between the type of immunosuppression and the presence of viruria was observed (Table 2). Considering the almost universal use of mycophenolatedalways in association with another immunosuppressive agentdthe ORs for azathioprine (0/11) and mycophenolate (18/352) were not calculated. DISCUSSION
This was the first epidemiologic cross-sectional study carried out in Argentina to evaluate the prevalence of BK viruria (>107 copies/mL) in renal transplant recipients during the 1st year after transplantation. The population under study showed the typical characteristics of the general population of kidney transplant recipients in Argentina. Furthermore, as a result of the number of patients included in the analysis (382), the number of sites participating (18), and the estimated prevalence of the condition under study (5%), we consider that the patients evaluated in this sample were significantly representative of the kidney transplant population in Argentina. The prevalence observed for an degree of BK viruria was 50/382 (13%). This figure is in accord with, though in the lowest end of the range, the international literature, which reports values of 10%e60% [4]. Although the prevalence observed for BK viruria >107 copies/mL was 4.7%, and these patients are at increased risk for developing BKVAN, that could not be confirmed in any case during the time of this cross-sectional analysis. In addition to the prevalence of BK viruria, this study analyzed the association between several risk factors previously described for BKVAN in the international literature [16], considering the presence of BK viruria >107 copies/mL to be a surrogate marker of nephropathy [17,18]. The analysis was not able to associate typically identified factors with the presence of viruria >107 copies/mL, but it showed a statistically significant increased risk for 2
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characteristics: donors older than 41 years and recipients older than 34 years. The lack of association between BKVAN and the traditional risk factors has been described by Sood et al [19]. This was the first multicenter study conducted in Argentina to determine the prevalence of BK viruria in renal transplant recipients. Because of the growing number of the population susceptible to this infection, it is important that accurate information regarding the situation in our country be available. REFERENCES [1] Lin PL, Vats AN, Green. BK virus infection in renal transplant recipients. Pediatr Transplant 2001;5:398e405. [2] de Caprio JA, Imperiale MJ, Major EO. Polyomavirus. In: Knipe DM, Howley PM, Cohen JI, et al., editors. Fields’ virology. 6th ed. Philadelphia: Lippincott Williams; 2013. pp. 1633e61. [3] Priftakis P. Studies on Human polyomavirus infection in immunosuppressed patients and in patients with polyoma related tumors [thesis]. Division of Experimental Oncology, Department of Oncology-Pathology, Cancer Center Karolinska, Karolinska Institute, Stockholm, Sweden; 2001. p 9e24. [4] Hirsch HH, Brennan D, Drachenberg CB, et al. Polyomavirusassociated nephropathy in renal transplantation: interdisciplinary analyses and recommendations. Transplantation 2005;10:1277e86. [5] Nickeleit V, Hirsch HH, Binet IF, et al. Polyomavirus infection of renal allograft recipients: from latent infection to manifest disease. J Am Soc Nephrol 1999;10:1080e9. [6] Nickeleit V, Hirsch HH, Zeiler M, et al. BK-virus nephropathy in renal transplants-tubular necrosis, MHC-class II expression and rejection in a puzzling game. Nephrol Dial Transplant 2000;15: 324e32. [7] Randhawa PS, Demetris AJ. Nephropathy due to polyomavirus type BK. N Engl J Med 2000;342:1361e3. [8] Schaub S, Hirsch HH, Dickenmann M, et al. Reducing immunosuppression preserves allograft function in presumptive and
SCHIAVELLI, BONAVENTURA, RIAL ET AL definitive polyomavirus-associated nephropathy. Am J Transplant 2010;10:2615e23. [9] Herman J, van Ranst M, Snoeck R, et al. Polyomavirus infection in pediatric renal transplant recipients: evaluation using a quantitative real-time PCR technique. Pediatr Transplant 2004;8:485e92. [10] Vats A, Shapiro R, Randhawa P, et al. Quantitative viral load monitoring and cidofovir therapy for the management of BK viruseassociated nephropathy in children and adults. Transplantation 2003;75:105e12. [11] Hirsch HH. BK virus: opportunity makes a pathogen. Clin Infect Dis 2005;41:354e60. [12] Weinstein L, Swartz MN. Pathogenic properties of invading micro-organisms. In: Sodeman Jr WA, Sodeman WA, editors. Pathologic physiology: mechanisms of disease. Philadelphia: Saunders; 1974. pp. 457e72. [13] Kasiske BL, Zeier MG, Chapman JR, et al. KDIGO clinical practice guideline for the care of kidney transplant recipients: a summary. Kidney Int 2010;77:299e311. [14] Naing L, Winn T, Rusli BN. Practical issues in calculating the sample size for prevalence studies. Arch Orofac Sci 2006;1: 9e14. [15] Bárcena-Panero A, Echevarría JE, Romero-Gómez MP, et al. Development and validation with clinical samples of internally controlled multiplex real-time PCR for diagnosis of BKV and JCV infection in associated pathologies. Comp Immunol Microbiol Infect Dis 2012;35:173e9. [16] Hirsch HH. BK virus replication and disease in solid organ transplant recipients: an update. Curr Opin Organ Transpl 2003;8: 262e8. [17] Dharnidharka VR, Cherikh WS, Abbott KC. An OPTN analysis of national registry data on treatment of BK virus allograft nephropathy in the United States. Transplantation 2009; 87:1019e26. [18] Hirsch HH, Vincenti F, Friman S, et al. Polyomavirus BK replication in de novo kidney transplant patients receiving tacrolimus or cyclosporine: a prospective, randomized, multicenter study. Am J Transplant 2013;13:136e45. [19] Sood P, Senanayake S, Sujeet K, et al. Lower prevalence of BK virus infection in African American renal transplant recipients: a prospective study. Transplantation 2012;93:291e6.