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Keywords:

  • Cytomegalovirus (CMV);
  • death;
  • graft failure;
  • graft loss;
  • liver transplantation;
  • mortality

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. Disclosure
  9. References
  10. Supporting Information

In the era of effective antiviral chemoprophylaxis, cytomegalovirus (CMV) disease has been inconsistently associated with increased mortality in liver transplant (LT) recipients. A retrospective study evaluating the association of CMV infection and disease occurring within 1 year of transplant with the endpoints of death or the combined endpoint of graft loss or death was undertaken in a cohort of 227 CMV donor seropositive, recipient seronegative first LT recipients. Associations were evaluated using Cox proportional hazards regression models. CMV infection and disease occurred in 91 (40%) and 43 (19%) patients, respectively. Forty-eight (21%) died while 58 (26%) sustained graft loss or death. In multivariable analysis, CMV infection was associated with an increased risk of death (RR: 2.24, p = 0.008) and graft loss or death (RR: 2.85, p < 0.001). CMV disease was also associated with an increased risk of death (RR: 2.73, p = 0.003) and graft loss or death (RR: 3.04, p = 0.001). CMV infection and disease occurring within the first year after LT in high-risk recipients is associated with increased risk of death and of graft loss or death. Investigation of strategies to further reduce the risk of CMV infection and disease in high-risk LT recipients is warranted.


Abbreviations: 
CMV

cytomegalovirus

LT

liver transplant

D+

donor seropositive

R−

recipient seronegative

IV

intravenous

OKT3

muromonab

PCR

polymerase chain reaction

CI

confidence intervals

RR

relative risks

HCV

hepatitis C virus

MELD

model for end-stage liver disease

Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. Disclosure
  9. References
  10. Supporting Information

Cytomegalovirus (CMV) infection and disease in liver transplant (LT) recipients have been associated with numerous adverse outcomes. The associated indirect complications of CMV include increased risk of infections (bacterial, fungal and viral), hepatic allograft rejection and vanishing bile duct syndrome (1,2). The direct effects of CMV in LT recipients include CMV syndrome and end-organ tissue damage with CMV gastroenteritis and CMV hepatitis. Without antiviral prophylaxis, it is estimated that 44–65% of high-risk LT recipients of CMV donor seropositive (D+)/recipient seronegative (R−) seromatch develop CMV disease during the first year following LT (1–5). Following the introduction of CMV prophylaxis administered during the first 3 months after LT, this incidence decreased to an estimated 12–30% (1,4,6). Although CMV prophylaxis has decreased the 1-year incidence of CMV disease, the development of late-onset CMV disease following the discontinuation of viral prophylaxis remains a clinical challenge.

In the era of effective CMV prophylaxis, two retrospective cohort studies have suggested an increased risk of mortality in LT recipients who develop CMV disease (7,8). Both of these studies included patients of all four CMV seromatches of donor and recipient, and examined mortality at 1 year after LT. CMV D+/R− seromatch was the only risk factor independently associated with development of CMV disease in both studies. In a recent study involving 67 patients of CMV D+/R− seromatch Arthurs et al. observed that patients who developed CMV disease were approximately 1.5 times more likely to die or experience graft loss (6). However, the study was underpowered and these findings did not reach statistical significance. Thus, the relationship between CMV disease and patient and graft survival in high-risk LT recipients in the current era of antiviral prophylaxis remains uncertain. The objective of this study was to evaluate the associations of CMV infection and CMV disease with death and the combined endpoint of graft loss or death in a large series of high-risk LT recipients.

Material and Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. Disclosure
  9. References
  10. Supporting Information

Patient population

This retrospective cohort study evaluated 227 consecutive LT recipients of CMV seromatch D+/R− who underwent first LT at Mayo Clinic Florida between January 1, 2003 and December 31, 2008. Patients who had combined organ transplants were excluded. LT recipients received CMV prophylaxis with either intravenous (IV) or oral, ganciclovir or valganciclovir through day 100 after LT. Patients who received alternative forms of CMV prophylaxis were excluded from the study. Treatment of CMV infection and disease during the study period was consistent with the current American Society of Transplantation infectious disease guidelines for CMV at the time of the study (9). Patients received treatment for CMV infection and disease with either IV ganciclovir or valganciclovir. CMV infection was defined as the isolation of CMV by viral culture, CMV pp65 antigenemia or detection of CMV by nucleic acid amplification or immunostaining in any body fluid or tissue specimen in asymptomatic patients. CMV disease with either end organ tissue damage or CMV syndrome was defined as per established criteria in transplant patients (10).

Immunosuppresion during the study period consisted of a three-drug regimen: tacrolimus, mycophenolate mofetil or azathioprine and prednisone. Mycophenolate mofetil or azathioprine was discontinued by 4 months after LT or earlier in the setting of malignancy, infection, bone marrow suppression or gastrointestinal side effects. Prednisone was tapered and discontinued by 4 months after LT unless there was graft rejection, inadequate primary immunosuppression or conversion to a sirolimus-based regimen. Basiliximab induction was used in patients with renal insufficiency, defined by a serum creatinine greater than 1.5 mg/dL at the time of LT, to delay the initiation of tacrolimus.

The study was approved by the Institutional Review Board of the Mayo Foundation.

Clinical follow-up

Patients had allograft biopsies performed routinely on day 7, at 4 months and once yearly after LT. Allograft biopsies were also performed for the evaluation of hepatic decompensation. Patients with moderate to severe acute cellular rejection were treated with IV methylprednisolone 1–3 g, divided into three alternate-day doses. Muromonab (OKT3) or antithymocyte globulin infusion was reserved for patients with acute cellular rejection resistant to IV methylprednisolone. Routine surveillance for CMV infection was performed weekly with CMV pp65 antigenemia assay or blood CMV quantitative polymerase chain reaction (PCR) during the first 8 weeks, at 4 months and at 12 months after LT. Liver biopsy specimens and urine specimens were also evaluated for evidence of CMV by PCR at 4 and 12 months after LT. Patients with clinical suspicion of CMV disease underwent blood testing with CMV pp65 antigenemia assay or blood CMV quantitative PCR.

Information about patient and donor characteristics at the time of transplant, operative and postoperative clinical variables and events that have been associated with CMV infection, CMV disease, graft loss or death were gathered from Mayo Clinic Florida LT databases and patient medical records. First episodes of CMV infection, CMV disease, bacterial infection, fungal infection, moderate to severe acute cellular rejection and abdominal reoperation (excluding liver retransplantation) occurring within the first year after LT were identified. If the patient received a second LT within the first year of the original transplant, data were only collected for the time period of the first LT. Date of graft loss in those patients who had liver retransplantation and date of death were collected through the end of follow-up. Treatment of CMV infection, CMV disease and date of last follow-up were recorded. If the patient was not diagnosed with CMV infection prior to the development of CMV disease, they were then considered to have CMV infection and disease simultaneously. Patients who experienced death were assumed to have graft loss simultaneously.

Statistical analysis

The Kaplan–Meier method was used to estimate the cumulative incidence of CMV infection, CMV disease, death and graft loss or death after LT, along with 95% confidence intervals (CI). The two primary endpoints of interest were death and the combined endpoint of graft loss or death, each occurring after LT. The associations of CMV infection and CMV disease with the two endpoints were evaluated using Cox proportional hazards regression models. Single variable Cox models were utilized in an exploratory analysis, as well as multivariable Cox models adjusting for potentially confounding variables in the primary analysis. Potentially confounding variables showing the strongest single variable associations with the given endpoint were adjusted for in the multivariable analysis, allowing for no more than one variable in the model for every 10 patients who experienced the given endpoint (11). The sensitivity of results to the additional adjustment for each remaining variable not included in the aforementioned multivariable analysis was examined. Relative risks (RR) and 95% CI were estimated. Secondary analyses were performed for the endpoints of death and graft loss or death within 1 and 2 years of LT, where single variable and multivariable analyses were performed as previously described. The variables CMV infection, CMV disease, bacterial infection, fungal infection, abdominal reoperation, moderate to severe acute cellular rejection, renal replacement therapy, length of hospital stay and treatment of CMV infection and disease were considered as time-varying covarites in Cox regression analysis as all of these variables occur after LT. The Length of hospital stay (≤14 days, >14 days) was dichotomized for utilization in Cox regression analysis as a time-varying covariate. p-Values ≤ 0.05 were considered statistically significant. All statistical analyses were performed using S-Plus (version 8.0.1; Insightful Corporation, Seattle, WA, USA).

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. Disclosure
  9. References
  10. Supporting Information

Patient, operative, donor and postoperative information

Patient baseline characteristics, operative information, donor information and post-LT complications for the cohort of 227 CMV D+/R− LT recipients are summarized in Table 1. The median age of the cohort was 54 years, the majority of LT recipients were males (73%), the most common diagnosis for end stage liver disease was chronic hepatitis C virus (HCV) (36%), and the median model for end-stage liver disease (MELD) score was 17. The median length of follow-up in the cohort was 40.6 months (range 0.7–85.2 months). The majority of the cohort (93%) received valganciclovir for CMV prophylaxis.

Table 1.  Patient baseline characteristics, operative information, donor information and postliver transplant complications
VariableSummary (N = 227)
  1. The sample median (minimum, maximum) is given for numerical variables. MELD, model for end-stage liver disease; CMV, cytomegalovirus; HLA, human leukocyte antigen.

Patient characteristics
 Age54 (16, 80)
 Gender (male)166 (73%)
 BMI28 (18, 54)
 Diabetes54 (24%)
 Principal liver disease diagnosis
   Chronic hepatitis C81 (36%)
   Alcohol-related liver disease34 (15%)
   Cryptogenic cirrhosis33 (15%)
   Primary sclerosing cholangitis27 (12%)
   Other52 (23%)
 MELD score17 (6, 46)
 Hospitalization on the date of liver transplant23 (10%)
 Intensive care unit on the date of liver transplant8 (4%)
 Organ-perfusion support on the date of liver transplant1 (<1%)
 Malignancy found on explanted native liver70 (31%)
Operative information
 Operative time (minutes)239 (107, 745)
 Basiliximab during liver transplant60 (26%)
 Units of red blood cells received8 (0, 103)
Donor characteristics
 Age50 (9, 88)
 Gender (male)131 (58%)
 Donation after cardiac death24 (11%)
 Donor liver steatosis
   ≤5%202 (89%)
   6–30%21 (9%)
   31– 60%4 (2%)
 Donor risk index1.70 (0.95, 3.23)
 Donor/recipient gender incompatibility93 (41%)
 Number of HLA-A donor/recipient mismatches (0 or 1)92 (41%)
 Number of HLA-B donor/recipient mismatches (0 or 1)59 (26%)
 Number of HLA-DR donor/recipient mismatches (0 or 1)88 (39%)
Post-LT complications
 Bacterial infection90 (40%)
 Fungal infection16 (7%)
 Moderate to severe acute cellular rejection58 (26%)
 Treatment with antithymocyte globulin2 (1%)
 Abdominal reoperation29 (13%)
 Renal replacement therapy25 (11%)
 Length of hospital stay7 (4, 179)
 CMV infection91 (40%)
 CMV disease43 (19%)

CMV infection and disease

Within the first year following LT, 91 patients (40%) developed CMV infection. Figure 1 displays the cumulative incidence of CMV infection and CMV disease after LT. At 3, 6 and 12 months following LT, the estimated cumulative incidence of CMV infection was 9% (95% CI: 5–12%), 32% (95% CI: 26–38%) and 40% (95% CI: 33–46%).

image

Figure 1. Estimated cumulative incidence of CMV infection and CMV disease after liver transplant.

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A total of 43 patients (19%) developed CMV disease within the first year following LT. As displayed in Figure 1, at 3, 6 and 12 months following LT, the estimated cumulative incidence of CMV disease was 0.4% (95% CI: 0.0–1.3%), 14% (95% CI: 9–18%) and 19% (95% CI: 14–24%). The most common presenting CMV disease diagnosis was CMV syndrome (58%), followed by CMV hepatitis (19%), CMV gastroenteritis (14%), CMV pneumonitis (7%) and CMV transverse myelitis (2%).

Nineteen patients developed CMV infection without disease within the first 3 months. CMV infection appeared in five patients after discontinuation of antiviral prophylaxis for leukopenia or normalization of renal function on a renal adjusted dose. Likely cause for the appearance of CMV infection on prophylaxis was not ascertained for the remaining 14 or for the appearance of CMV disease in one patient. Resistance of CMV to ganciclovir was not detected in any patient.

Twenty patients (22%) with CMV infection and 3 patients (7%) with CMV disease were not treated. CMV infection in 15 patients was not treated because of low level of virus: urine only by PCR (n = 3); liver biopsy only by PCR (n = 2); urine and liver only by PCR (n = 1); in blood only at low level by PCR (≤100 copies/ml, n = 7) or pp65 antigen (1 cell, n = 2). Two patients with CMV disease did not adhere to therapy. Likely causes for lack of treatment of five patients with infection and one with disease were not ascertained.

Death and graft loss

In the study cohort, 48 patients (21%) died and 58 patients (26%) experienced graft loss or death. At 1, 3 and 5 years after LT, the estimated cumulative incidence of death was 8% (95% CI: 4–11%), 15% (95% CI: 10–20%) and 24% (95% CI: 17–31%), respectively, while the estimated cumulative incidence of graft loss or death was 12% (95% CI: 8–17%), 20% (95% CI: 15–25%) and 30% (95% CI: 22–37%), respectively. The causes of death and graft loss are provided in Table 2.

Table 2.  Causes of graft loss and death
EtiologyGraft loss and Retransplant (N = 18)Death (N = 48)
  1. Eight patients retransplanted died during follow-up; these eight appear in both columns.

  2. Forty-eight patients died and by definition sustained graft loss at death.

  3. Ten patients retransplanted survived through follow-up + 48 deaths = 58 graft loss or death.

Recurrent hepatitis C23
Primary hepatic nonfunction41
Ischemic cholangiopathy6 
Hepatic artery thrombosis4 
Primary sclerosing cholangitis1 
Portal vein thrombosis11
Hepatic veno-occlusive disease 2
Nonalcoholic steatohepatitis 1
Metastatic cancer 15
Sepsis 10
Hemorrhage 2
Cardiac arrest 2
Uremia 1
Unknown 10

Association of CMV infection with death and graft loss after LT

As displayed in Table 3, in single variable analysis without adjustment for other variables, CMV infection within the first year following LT was associated with an increased risk of death (RR: 2.42, p = 0.004) and also with an increased risk of graft loss or death (RR: 2.92, p < 0.001). This is further illustrated in Figure 2a and b, which show the cumulative incidences of death and graft loss or death, respectively, according to development of CMV infection by 6 months following LT. As information regarding CMV infection and disease is not known at the time of LT, it was necessary to choose a time after LT to begin the display of Kaplan–Meier curves. Six months post-LT was chosen as a reasonable time to begin Kaplan–Meier curves because by that point most episodes of CMV infection and disease had occurred, yet most deaths and graft losses had not.

Table 3.  Associations of CMV infection and CMV disease within 1 year of liver transplant with death and graft loss or death occurring at any time after liver transplant.
AssociationSingle variable analysisMultivariable analysis
RR (95% CI)p-ValueRR (95% CI)p-Value
  1. Relative risks and p-values result from the Cox proportional hazards models.

  2. Multivariable models were adjusted for variables most highly associated with the given endpoint, allowing for no more than one variable in the multivariable model for every 10 patients who experienced the endpoint. For the endpoint of death, these variables were malignancy found on explanted native liver, bacterial infection and length of hospital stay >14 days. For the endpoint of graft loss or death, these variables were malignancy found on native liver, bacterial infection, abdominal reoperation and renal replacement therapy.

  3. RR, relative risk; CI, confidence interval; CMV, cytomegalovirus; MELD, model for end-stage liver disease.

CMV infection with:
 Death2.42 (1.34, 4.39)0.0042.24 (1.24, 4.05)0.008
 Graft loss or death2.92 (1.64, 5.18)<0.0012.85 (1.62, 5.01)<0.001
CMV disease with:
 Death2.60 (1.34, 5.05)0.0052.73 (1.40, 5.34)0.003
 Graft loss or death2.91 (1.52, 5.59)0.0013.04 (1.56, 5.92)0.001
image

Figure 2. (A) Cumulative incidence of death according to development of CMV infection by 6 months after LT. (B) Cumulative incidence of graft loss or death according to development of CMV infection by 6 months after LT. (C) Cumulative incidence of death according to development of CMV disease by 6 months after LT. (D) Cumulative incidence of graft loss or death according to development of CMV disease by 6 months after LT.

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As displayed in Table 4, the three variables most highly associated with death were malignancy found on explanted liver (RR: 3.49, p < 0.001), bacterial infection (RR: 4.06, p < 0.001) and length of hospital stay greater than 14 days (RR: 2.87, p = 0.003). The four variables most highly associated with the combined endpoint of graft loss or death were malignancy found on explanted liver (RR: 2.42, p = 0.001), bacterial infection (RR: 4.99, p < 0.001), abdominal reoperation (RR: 3.30, p < 0.001) and renal replacement therapy (RR: 3.32, p < 0.001). When adjusting for the aforementioned variables, the associations of CMV infection with an increased risk of death (RR: 2.24, 95% CI: 1.24–4.05, p = 0.008) and graft loss or death (RR: 2.85, 95% CI: 1.62–5.01, p < 0.001) remained significant.

Table 4.  Single variable associations of patient characteristics, operative information, donor information and postliver transplant complications (other than CMV infection and CMV disease) with the endpoints of death and graft loss or death
VariableAssociation with deathAssociation with graft loss or death
RR (95% CI)p-ValueRR (95% CI)p-Value
  1. Organ-perfusion support on date of liver transplant and treatment with antithymocyte globulin were not included due to the very small number of patients with these conditions.

  2. Relative risks and p-values result from single variable Cox proportional hazards models.

  3. RR, relative risk; CI, confidence interval; CMV, cytomegalovirus; MELD, model for end-stage liver disease; HLA, human leukocyte antigen.

Patient characteristics
 Age (10-year increase)1.35 (1.02, 1.78)0.0371.10 (0.87, 1.41)0.42
 Gender (male)2.59 (1.10, 6.10)0.0302.03 (0.99, 4.13)0.052
 BMI (10-unit increase)0.87 (0.54, 1.39)0.550.91 (0.60, 1.40)0.68
 Diabetes1.12 (0.58, 2.16)0.731.07 (0.58, 1.94)0.84
 Principal liver disease diagnosis
   Chronic hepatitis C1.84 (1.05, 3.25)0.0341.62 (0.96, 2.71)0.069
   Alcohol-related liver disease1.20 (0.58, 2.49)0.620.91 (0.45, 1.86)0.80
   Cryptogenic cirrhosis0.47 (0.17, 1.29)0.140.92 (0.44, 1.95)0.84
   Primary sclerosing cholangitis1.26 (0.56, 2.80)0.581.37 (0.67, 2.78)0.39
   Other0.41 (0.16, 1.02)0.0560.38 (0.16, 0.89)0.026
 MELD score (10-unit increase)0.49 (0.28, 0.87)0.0140.56 (0.35, 0.91)0.018
 Hospitalization on date of liver transplant1.09 (0.43, 2.76)0.850.83 (0.33, 2.06)0.68
 Intensive care unit on date of liver transplant0.66 (0.09, 4.79)0.680.49 (0.07, 3.53)0.48
 Malignancy found on explanted native liver3.49 (1.97, 6.19)<0.0012.42 (1.44, 4.05)0.001
Operative information
 Operative time (60-min increase)1.17 (1.03, 1.33)0.0181.20 (1.07, 1.35)0.002
 Basiliximab during liver transplant1.63 (0.88, 3.03)0.121.43 (0.81, 2.52)0.22
 Units of red blood cells received (doubling)1.14 (0.87, 1.49)0.340.98 (0.77, 1.25)0.88
Donor characteristics
 Age (10-year increase)1.24 (1.06, 1.45)0.0091.21 (1.05, 1.40)0.009
 Gender (male)0.66 (0.37, 1.16)0.150.71 (0.42, 1.18)0.19
 Donation after cardiac death1.21 (0.48, 3.07)0.690.92 (0.37, 2.31)0.86
 Donor liver steatosis (10% increase)1.35 (1.04, 1.75)0.0241.26 (0.99, 1.62)0.065
 Donor risk index (1-unit increase)2.33 (1.24, 4.38)0.0091.98 (1.13, 3.47)0.017
 Donor/recipient gender incompatibility1.73 (0.98, 3.05)0.0591.74 (1.04, 2.92)0.036
 Number of HLA-A donor/recipient mismatches (0 or 1)1.02 (0.57, 1.82)0.951.10 (0.65, 1.86)0.71
 Number of HLA-B donor/recipient mismatches (0 or 1)1.59 (0.88, 2.88)0.131.38 (0.80, 2.39)0.25
 Number of HLA-DR donor/recipient mismatches (0 or 1)1.43 (0.81, 2.53)0.211.05 (0.62, 1.78)0.85
Post-LT complications
 Bacterial infection4.06 (2.20, 7.50)<0.0014.99 (2.80, 8.89)<0.001
 Fungal infection2.18 (0.86, 5.55)0.102.64 (1.12, 6.23)0.026
 Moderate to severe acute cellular rejection1.24 (0.66, 2.36)0.511.38 (0.77, 2.46)0.28
 Abdominal re-operation2.25 (1.12, 4.52)0.0233.30 (1.81, 6.04)<0.001
 Renal replacement therapy2.98 (1.43, 6.23)0.0043.32 (1.71, 6.44)<0.001
 Length of hospital stay (>14 days)2.87 (1.44, 5.69)0.0032.66 (1.36, 5.21)0.004

The sensitivity of results to further individual adjustment for each remaining variable listed in Table 4 that was not adjusted for in the aforementioned multivariable analysis is displayed in Supporting Tables S1 and S2. After these additional adjustments, the associations of CMV infection with increased risk of death (all RRs ≥ 1.83, all p ≤ 0.050) and increased risk of graft loss or death (all RRs ≥ 2.17, all p ≤ 0.010) remained significant. No significant increase or decrease in the risk of death (p = 0.59) or the combined endpoint of graft loss or death (p = 0.88) was observed in the 20 patients who developed CMV infection who were not treated compared to 71 patients who developed CMV infection and were treated.

Association of CMV disease with death and graft loss after LT

As displayed in Table 3, in single variable analysis, CMV disease within the first year following LT was associated with an increased risk of death (RR: 2.60, p = 0.005) and the composite endpoint of graft loss or death (RR: 2.91, p = 0.001). This is further illustrated in Figure 2c and d, which show the cumulative incidences of death and graft loss or death, respectively, according to development of CMV disease by 6 months following LT. In multivariable analysis with adjustment for the previously mentioned covariates, the associations of CMV disease with an increased risk of death (RR: 2.73, 95% CI: 1.40–5.34, p = 0.003) and graft loss or death (RR: 3.04, 95% CI: 1.56–5.92, p = 0.001) remained significant. As displayed in Supporting Tables S1 and S2, after adjustment for each additional variable in Table 4 that was not included in the aforementioned multivariable analysis, the associations of CMV disease with increased risk of death (all RRs ≥ 2.23, all p ≤ 0.020) and increased risk of graft loss or death (all RRs ≥ 2.54, all p ≤ 0.006) remained significant.

Associations of CMV infection and disease with death and graft loss within 1 and 2 years of LT

In Table 5 an evaluation of the associations of CMV infection and disease with death and graft loss or death occurring within 1 and 2 years of LT is presented. Single variable analysis and multivariable analysis were performed, though multivariable analysis was more limited than that performed for death or graft loss through end of follow-up, due to the fewer number of patients experiencing these endpoints within 1 and 2 years of LT. (See Table 5 footnote for details on which variables were adjusted.) The increased risks of death and of graft loss or death associated with the development of CMV infection or disease remained when considering death and graft loss within 1 and 2 years of LT.

Table 5.  Associations of CMV infection and CMV disease within 1 year of liver transplant with death and graft loss or death occurring within 1 and 2 years of liver transplant
AssociationDeath and graft loss within 1 year of liver transplantDeath and graft loss within 2 years of liver transplant
RR (95% CI)p-valueRR (95% CI)p-value
  1. Relative risks and p-values result from the single variable Cox proportional hazards models.

  2. The following variables were adjusted for in multivariable analysis: death within 1 year of liver transplant (no adjustment owing to limited number of patients [18] experiencing this outcome); death within 2 years of liver transplant (adjusted for malignancy found on explanted native liver and bacterial infection [30 total deaths within 2 years of liver transplant]); graft loss or death within 1 year of liver transplant (adjusted for bacterial infection [28 total graft loss or death within 1 year of liver transplant]); graft loss or death within 2 years of liver transplant (adjusted for bacterial infection, abdominal re-operation and renal replacement therapy [41 total graft loss or death within 2 years of liver transplant]).

  3. RR, relative risk; CI, confidence interval; CMV, cytomegalovirus.

CMV infection with
  Death
   Single variable analysis3.82 (1.35, 10.76)0.0113.01 (1.38, 6.56)0.006
   Multivariable analysisN/AN/A2.42 (1.13, 5.20)0.023
 Graft loss or death
   Single variable analysis5.31 (2.20, 12.82)<0.0013.52 (1.72, 7.19)0.001
   Multivariable analysis4.89 (2.03, 11.74)<0.0013.25 (1.60, 6.57)0.001
CMV disease with
 Death
   Single variable analysis2.74 (0.81, 9.26)0.103.02 (1.31, 6.94)0.010
   Multivariable analysisN/AN/A2.68 (1.18, 6.10)0.019
 Graft loss or death
  Single variable analysis3.98 (1.25, 12.70)0.0203.31 (1.48, 7.41)0.004
  Multivariable analysis3.22 (1.03, 10.05)0.0442.89 (1.29, 6.48)0.010

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. Disclosure
  9. References
  10. Supporting Information

Prior to the introduction of effective antiviral chemoprophylaxis in the form of ganciclovir or valganciclovir, CMV disease and high-risk CMV seromatch (D+/R−) were associated with increased risk of death or graft loss after liver transplantation (12–15). Following the introduction of ganciclovir or valganciclovir for chemoprophylaxis, two meta-analyses have documented an attenuation of these associations in solid organ transplant recipients (16,17). The degree of attenuation and the clinical significance of the remaining associations have however remained controversial in LT. With effective chemoprophylaxis for the first 100 days after LT, reports have failed to consistently identify associations of late-onset CMV disease with graft loss or death, especially in high-risk CMV LT recipients (6–8,18). In this examination of the largest cohort of high-risk CMV D+/R− LT recipients studied to date, all of whom were given ganciclovir or valganciclovir during the first 100 days after transplant, we provide convincing evidence that patients who develop CMV infection or disease within the first year after LT are more likely to experience death or graft loss than patients who remain free of CMV infection and disease. Although it is important to underscore that we cannot conclude that CMV infection and disease cause these poor outcomes, the increased risks of death and graft loss that we observed in patients who developed CMV infection and disease were independent of a large number of patient, operative, donor and postoperative variables. These associations also remained when considering only death and graft loss occurring within 1 and 2 years of LT as endpoints.

Studies from Limaye et al. found a consistent and significant association of CMV disease with an increased risk of death at 1 year after LT in 2004 (RR 14, p = 0.0007) and in 2006 (RR 5.1, p = 0.002) (7,8). Although both of the cohort studies included a large sample size of 259 and 437 LT recipients of all four CMV seromatches, their CMV D+/R− group consisted of 38 and 77 patients, respectively. The majority of the patients who experienced CMV disease in both studies were CMV D+/R−; however, mortality in this group was not assessed (7,8). Most recently, Arthurs et al. retrospectively assessed the development of CMV disease in 67 CMV D+/R− LT recipients with the risk of graft loss or death, and although there was an increased risk of the outcomes in patients who developed CMV disease, this was not statistically significant in this small, underpowered series (RR 1.5, p = 0.58) (6). In contrast, our study with 227 D+/R− LT recipients had sufficient power to reveal a statistically significant increased risk of graft loss or death in patients who experienced CMV infection or disease.

The 6-month cumulative incidence of CMV disease in our cohort mainly receiving valganciclovir (93%) for prophylaxis was considerably lower at 14% versus 25% in the Arthurs study (6). Our 6-month incidence of CMV disease was also lower (14% vs. 19%) when compared to the valganciclovir arm in LT recipients of the PV 16000 trial (19). It is reasonable to assume that late-onset CMV disease occurs in at least 14% to 19% in high-risk LT recipients of CMV D+/R− seromatch while on valganciclovir prophylaxis. If cases of late-onset CMV disease were missed in our retrospective investigation, then our estimates of the cumulative incidence of this endpoint would be slightly low.

Several studies, including ours, demonstrate that the cumulative incidences of late-onset CMV infection and disease stabilize after 6 months of LT or solid organ transplant (6–8,19,20). This phenomenon may be explained by the progressive tapering of immunosuppression that occurs at 4 months of LT, which allows the recipient to mount a more adequate cell-mediated immune response against CMV. If this is true, extending CMV prophylaxis from 3 to 6 months for high-risk LT recipients might decrease their risk of graft loss or death through the end of the first year after LT and thereafter. This was recently explored in a multi-centered randomized control trial of high-risk kidney transplant recipients (CMV D+/R−) (21). Valganciclovir prophylaxis was compared at 200 days versus 100 days in 326 high-risk kidney transplant recipients (IMPACT study). The 12-month cumulative incidence of CMV disease in the 200 day arm was significantly reduced when compared to the 100 day arm (16.1% vs. 36.8%, p < 0.0001). Similar results were also evident for the cumulative incidence of CMV viremia at 12-months (37.4% vs. 50.9%, p = 0.015). Examination of longer term outcomes in this trial has found that the reduction in the incidence of CMV disease in the 200-day valganciclovir prophylaxis arm is sustained up to 2 years after transplant (22).

The current guidelines for the management of CMV in solid organ transplantation by the American Society of Transplantation (23) and The Transplantation Society (24) recommend ganciclovir or valganciclovir for a total of 3–6 months after LT in D+/R− patients. However, if the development of late-onset CMV infection and disease increases the risk of graft loss or death, then an extension of prophylaxis to 6 months in all high-risk LT recipients would seem reasonable. Further studies are warranted in high-risk LT recipients to determine whether extending CMV prophylaxis to 6 months would significantly decrease their risk for graft loss or death. Side effects and cost effectiveness of prolonged valganciclovir would need to be examined in our patient population. Based on the results of the IMPACT study, extending CMV prophylaxis to 200 days after kidney transplant with valganciclovir appeared to be a cost-effective strategy in the management of CMV disease (25).

One of the greatest strengths of the study is the large sample size of high-risk patients for CMV infection and disease in LT recipients, whereas previous smaller studies had similar findings but did not have adequate power. An additional strength was the collection of numerous covariates (patient, operative, donor and post-transplant complication information) for adjustment in our multivariable Cox regression analyses. Thus, although we cannot make this claim with certainty, the associations of CMV infection and disease with graft loss and death that we identified appear unlikely to be caused by confounding variables. Limitations of the study are related to its retrospective nature in a single transplant center, potentially introducing bias to the data collection and definition of clinical events that occurred, as well as bias related to incomplete capture of information on variables (e.g. undocumented noncompliance with protocol immunosuppression and CMV prophylaxis) and outcomes. Some caution should be applied to interpretation of the association between CMV infection during the first year following transplant and risk of death or of graft loss or death in these high-risk LT recipients. Asymptomatic CMV infection without disease in this and other similar studies was identified at arbitrary times following LT, times dictated by clinical protocols and usually during the first four months, not at anytime after LT. Whether and how CMV infection without disease appearing more than 4 months after LT is associated with increased risk of graft loss or death remains to be determined.

In the largest retrospective cohort study of first LT recipients of CMV D+/R− seromatch, development of CMV infection and disease within the first year following LT was associated with an increased risk of death and graft loss or death. Further studies are warranted to determine whether the extension of valganciclovir prophylaxis of high-risk LT recipients beyond 100 days after LT has any impact on the incidence of graft loss or death associated with the development of late-onset CMV infection and disease. Additionally, our study demonstrates that asymptomatic CMV infection occurs frequently after the discontinuation of viral chemoprophylaxis, and its association with these poor outcomes should be further explored.

Disclosure

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. Disclosure
  9. References
  10. Supporting Information

The manuscript was not prepared in any part by a commercial organization and was not funded in any part by a commercial organization or educational grant. The authors of this manuscript have no conflicts of interest to disclose as described by the American Journal of Transplantation.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. Disclosure
  9. References
  10. Supporting Information

Supporting Information

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgment
  8. Disclosure
  9. References
  10. Supporting Information

Table S1: Associations of development of CMV infection and CMV disease with death—further multivariable analysis.

Table S2: Associations of development of CMV infection and CMV disease with graft loss or death—further multivariable analysis.

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AJT_3618_sm_SuppMat.doc77KSupporting info item

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