Cytomegalovirus Infection in Postrenal Transplant Recipients: 18 Years’ Experience From a Tertiary Referral Center

Risk factors for graft loss and death among kidney transplant recipients: A competing risk analysis

INTRODUCTION

Kidney transplantation is the best therapeutical option for CKD patients. Graft loss risk factors are usually estimated with the cox method. Competing risk analysis could be useful to determine the impact of different events affecting graft survival, the occurrence of an outcome of interest can be precluded by another. We aimed to determine the risk factors for graft loss in the presence of mortality as a competing event.

METHODS

A retrospective cohort of 1454 kidney transplant recipients who were transplanted between July 1, 2008, to May 31, 2019, in Colombiana de Trasplantes, were analyzed to determine risk factors of graft loss and mortality at 5 years post-transplantation. Kidney and patient survival probabilities were estimated by the competing risk analysis. The Fine and Gray method was used to fit a multivariable model for each outcome. Three variable selection methods were compared, and the bootstrapping technique was used for internal validation as split method for resample. The performance of the final model was assessed calculating the prediction error, brier score, c-index and calibration plot.

RESULTS

Graft loss occurred in 169 patients (11.6%) and death in 137 (9.4%). Cumulative incidence for graft loss and death was 15.8% and 13.8% respectively. In a multivariable analysis, we found that BKV nephropathy, serum creatinine and increased number of renal biopsies were significant risk factors for graft loss. On the other hand, recipient age, acute cellular rejection, CMV disease were risk factors for death, and recipients with living donor had better survival compared to deceased-donor transplant and coronary stent. The c-index were 0.6 and 0.72 for graft loss and death model respectively.

CONCLUSION

We developed two prediction models for graft loss and death 5 years post-transplantation by a unique transplant program in Colombia. Using a competing risk multivariable analysis, we were able to identify 3 significant risk factors for graft loss and 5 significant risk factors for death. This contributes to have a better understanding of risk factors for graft loss in a Latin-American population. The predictive performance of the models was mild.

Cytomegalovirus in renal transplant recipients from living donors with and without valganciclovir prophylaxis and with immunosuppression based on anti-thymocyte globulin or basiliximab

BACKGROUND

In our population, anti-thymocyte globulin (ATG) of 1 mg/Kg/day for 4 days is used; which permits not using valgancyclovir (VGC) prophylaxis in some renal transplant recipients (RTR) with moderate risk (R+), to reduce costs. This study aimed to determine the incidence and risk of developing cytomegalovirus (CMV), with or without prophylaxis, when exposed to low doses of ATG or basiliximab (BSL).

PATIENTS AND METHODS

A retrospective cohort included 265 RTR with follow-up of 12 months. Prophylaxis was used in R-/D+ and some R+. Tacrolimus (TAC), mycophenolate mofetil, and prednisone were used in all patients. Logistic regression analysis was performed to estimate the risk of CMV in RTR with or without VGC.

RESULTS

Cytomegalovirus was documented in 46 (17.3%) patients: 20 (43.5%) with CMV infection, and 26 (56.5%) with CMV disease. Anti-thymocyte globulin was used in 39 patients (85%): 32 R+, six D+/R-, and one D-/R-. ATG was used in 90% (27 of 30) of patients with CMV and without prophylaxis. The multivariate analysis showed an association of risk for CMV with the absence of prophylaxis (RR 2.29; 95% CI 1.08-4.86), ATG use (RR 3.7; 95% CI 1.50-9.13), TAC toxicity (RR 3.77; 95% CI 1.41-10.13), and lymphocytes at the sixth post-transplant month (RR 1.77; 95% CI 1.0-3.16).

CONCLUSIONS

Low doses of ATG favored the development of CMV and a lower survival free of CMV compared with BSL. In scenarios where resources for employing VGC are limited, BSL could be an acceptable strategy.

Performance evaluation of the Roche cobas 6800 system for quantifying cytomegalovirus DNA in plasma and urine samples

INTRODUCTION

Cytomegalovirus (CMV) nucleic acid amplification testing is important for CMV infection diagnosis and management. CMV DNA is found in plasma and various other fluids, including urine. If CMV can be reliably detected in urine, it may be considered a non-invasive alternative to blood tests. The cobas 6800 system (Roche Diagnostics, Mannheim, Germany) is a Food and Drug Administration-approved testing platform for measuring CMV DNA in plasma.

OBJECTIVE

To evaluate the analytical performance of the cobas 6800 system and compare the clinical feasibility of CMV detection in plasma and urine samples.

STUDY DESIGN

Imprecision, linearity, limit of quantitation (LOQ), and cross-reactivity of the cobas 6800 system were assessed, and reference interval verification was performed. Plasma CMV DNA quantification was compared to CMV DNA values in urine samples obtained from 129 pediatric patients (<18 years of age) from March 2020 to May 2020 at a tertiary hospital.

RESULTS

The assay precision was within the acceptable range. Linearity was observed within the tested concentration range (2.36-6.33 log IU/mL) with a coefficient of determination of 0.9972. The LOQ was 34.5 IU/mL. The assay did not show cross-reactivity with 15 other viruses. Plasma and urine detection results were stratified into three categories: negative, <LOQ, and positive to analyze the degree of agreement with the results. The quadratic weighted kappa value was 0.623 (P = 0.000), showing substantial concurrence.

CONCLUSION

The cobas 6800 system offers good sensitivity, precision, and linearity and is suitable for monitoring CMV viral loads in the plasma and urine samples.