Delayed-onset primary cytomegalovirus disease after liver transplantation
Clinical practice guidelines recommend antiviral prophylaxis to cytomegalovirus (CMV) donor-positive/recipient-negative (D+/R−) liver transplant recipients. We assessed the outcome of this strategy by determining the incidence, clinical features, and risk factors of CMV disease among CMV D+/R− liver transplant recipients who received antiviral prophylaxis. Sixty-seven CMV D+/R− liver transplant recipients (mean age ± standard deviation: 49.5 ± 11.4 years; 75% male) received oral ganciclovir [n = 9 (13%)] or valganciclovir [n = 58 (87%)] prophylaxis for a median duration of 92 days (interquartile range: 91-100). No breakthrough CMV disease was observed during antiviral prophylaxis. However, primary CMV disease was observed in 2%, 25%, 27%, 27%, and 29% of patients at 1, 3, 6, 12, and 24 months, respectively, after antiviral prophylaxis was stopped. The incidence of delayed-onset primary CMV disease was similar between those who received oral ganciclovir and valganciclovir. Nine (47%) patients had CMV syndrome, 8 (42%) had gastrointestinal CMV disease, and 2 (11%) had CMV hepatitis. Female patients (P = 0.01) and younger age at transplant (P = 0.03) were associated with an increased risk, whereas diabetes mellitus (P < 0.001) was significantly associated with a lower risk of delayed-onset primary CMV disease. Allograft loss or mortality occurred in 8 (12%) patients during the median follow-up period of 3.31 (range: 0.8-5.9) years. No significant association was observed between CMV disease and patient and allograft survival. In conclusion, CMV disease remains a common complication in CMV D+/R− liver transplant patients during the contemporary era of antiviral prophylaxis. Female patients and younger patients are at increased risk of delayed-onset primary CMV disease. Liver Transpl 13: 1703–1709, 2007. © 2007 AASLD.
Throughout the era of liver transplantation, cytomegalovirus (CMV) has been the most important opportunistic infection that negatively influences the outcome of patients.1 Because of its numerous direct and indirect effects, CMV causes significant morbidity, and in studies conducted prior to the era of antiviral prophylaxis, CMV disease was an independent predictor of patient and allograft survival.2–6 The mechanism underlying the adverse association between CMV and transplant outcomes is viral immunomodulation, as illustrated by an increased rate of other opportunistic infections and the tendency to develop chronic allograft dysfunction among liver transplant recipients with CMV disease.2 In particular, the immunomodulating property of CMV has been suggested to hasten the recurrence and increase the risk of allograft failure and mortality among liver transplant recipients with chronic hepatitis C.3
With the availability of effective antiviral drugs, there has been remarkable progress in the control of CMV in terms of its prevention and treatment. In addition to directly reducing the incidence of CMV disease, there is an accumulating body of evidence indicating that antiviral prophylaxis is associated indirectly with a lower risk of biopsy-proven rejection after liver transplantation.7 Nonetheless, clinical observations suggest that the current strategy of CMV prevention is not optimal because many liver transplant recipients continue to develop CMV disease after completing antiviral prophylaxis.8 Indeed, in many liver transplant recipients, the use of CMV-specific prophylaxis has only shifted the onset of disease so that it now occurs at a later period after liver transplantation;9, 10 this condition is termed delayed-onset CMV disease.
CMV donor-positive/recipient-negative (D+/R−) serologic mismatch status is the single most important risk factor for delayed-onset CMV disease after liver transplantation.9 In addition, studies conducted in heterogeneous groups of CMV D+/R− solid organ transplant recipients suggest that a lower creatinine clearance,11 female gender,11 and acute allograft rejection12 are significantly associated with increased risk of delayed-onset CMV disease. However, studies that specifically address this clinically relevant issue in a homogeneous group of high-risk CMV D+/R− liver transplant recipients have not been conducted. The conduct of a study that is limited to only the high-risk liver transplant recipients is of significant clinical importance because risk factors certainly differ among the various solid organ transplant populations. Additionally, whether delayed-onset primary CMV disease negatively influences the outcome of CMV D+/R− liver transplant recipients, in terms of allograft and patient survival, is not known. It is in this context that we conducted this retrospective study to (1) determine the incidence and clinical features of delayed-onset primary CMV disease in a homogeneous high-risk population of CMV D+/R− liver transplant recipients who received standard antiviral prophylaxis, (2) assess clinical and demographic variables associated with delayed-onset CMV disease, and (3) assess the association between delayed-onset CMV disease and patient and allograft survival.
PATIENTS AND METHODS
Because CMV D+/R− mismatch liver transplant recipients have the highest risk of delayed-onset primary CMV disease, this particular serogroup was the subject of this study. In order to identify these patients, we screened all 397 patients who had undergone liver transplantation at the Mayo Clinic (Rochester, MN) during a 5-year period from January 1, 2000 to December 31, 2004. The eligibility criteria for inclusion in this retrospective study were (1) >18 years of age, (2) CMV D+/R− serostatus, (3) use of oral ganciclovir and valganciclovir prophylaxis, and (4) survival beyond 3 months after transplantation. The other CMV serogroups (CMV D+/R+, CMV D−/R+, and CMV D−/R−) were not included in this study because our main objective was to assess the features of primary CMV disease and because our clinical practice is not to provide anti-CMV prophylaxis to these groups. In compliance with Minnesota law, only patients who provided consent for the review of their medical records were included. This study was approved by the Institutional Review Board of the Mayo Foundation.
The medical records of all CMV D+/R− patients were reviewed for demographic data, clinical variables, and the outcomes of CMV disease, allograft loss, and death. Immunosuppressive therapy, acute allograft rejection and its treatment, and a comprehensive assessment of comorbid conditions with the use of the Charlson comorbidity index13 at 3 months were recorded. All patients were followed until death or the end of study (June 2006).
Anti-CMV Prophylaxis and Surveillance
In accordance with current guidelines,14 our clinical practice is to administer antiviral prophylaxis to all CMV D+/R− liver transplant recipients. On the day of liver transplantation, the patient receives intravenous (IV) ganciclovir, 5 mg/kg daily (adjusted on the basis of renal function), and as soon as the patient is able to tolerate oral medications, antiviral prophylaxis with oral ganciclovir, 1 g 3 times a day (prior to October 2001), or valganciclovir, 900 mg once daily (on or after October 2001), is begun and continued through 90-100 days after transplant. The dose of the medication was adjusted on the basis of creatinine clearance. Patients who developed acute rejection during the first year after transplantation also received anti-CMV prophylaxis during the course of treatment with IV methylprednisolone, muromonab-CD3 (OKT3), or antithymocyte globulin (rabbit) and for 4 weeks after antirejection therapy. CMV surveillance with the use of CMV polymerase chain reaction (PCR) assay was not performed routinely during and after antiviral prophylaxis. CMV PCR was used for the diagnosis of CMV disease, as indicated by clinical symptoms.
Patients received IV methylprednisolone at the time of liver transplantation. Maintenance immunosuppression consisted of mycophenolate mofetil, tacrolimus, and prednisone. Our clinical practice is to discontinue mycophenolate mofetil at 2 months after transplantation unless the patient has met criteria for continuation of therapy (that is, low tacrolimus level, treated acute allograft rejection). Likewise, the dose of prednisone is tapered off over 4 months after liver transplant, at which time prednisone is discontinued unless circumstances warrant its use, such as retransplantation or acute rejection. In the long term, patients were maintained on tacrolimus monotherapy.
Definitions of CMV Disease
CMV disease was defined according to previously published criteria15 and required the presence of clinical symptoms and signs compatible with CMV disease accompanied by the detection or isolation of CMV in blood or virologic and/or histologic detection in a biopsy specimen. CMV disease was categorized into CMV syndrome or tissue-invasive CMV disease. CMV syndrome was diagnosed with detection of CMV in the blood accompanied by fever, fatigue, malaise, leukopenia, thrombocytopenia, and/or arthralgias; other potential causes were excluded, and there was no evidence of tissue-invasive disease. Tissue-invasive CMV disease was diagnosed when there were clinical signs and symptoms of tissue invasion, such as diarrhea, elevated liver enzymes, or mucosal ulcerations, accompanied by virologic and/or histologic detection of CMV in a biopsy specimen. The mere detection of CMV in blood in the absence of clinical symptomatology was defined as CMV infection.
Descriptive statistics were used to characterize demographic data and clinical variables. The associations between demographic and clinical variables and CMV disease were assessed with Cox proportional hazard regression. For the purpose of assessing the relationship between immunosuppression and CMV disease, the specific immunosuppressive regimen was recorded at the time of discontinuation of anti-CMV prophylaxis. To assess the association between acute rejection and CMV disease, we considered acute rejection as a time-dependent factor in the Cox proportional hazard model. To assess the association between CMV disease and death or allograft loss, we considered CMV disease as a time-dependent factor in the Cox proportional hazard model. The validity of these models was assessed by the examination of Schoenfeld residuals. Statistical significance was set at P < 0.05.
Among the 397 patients who underwent liver transplantation at our institution during the 5-year study period, 86 (21.7%) had CMV D+/R− serostatus. Sixty-seven of the 86 CMV D+/R− patients met the eligibility criteria for inclusion in this study. Nineteen patients were excluded from analysis because of undocumented antiviral prophylaxis (n = 11), lack of consent for research participation (n = 4), and death from CMV-unrelated causes prior to 3 months after transplantation (n = 4). Fifty (75%) of the 67 patients were male. The mean (± standard deviation) age of the patients was 49.5 ± 11.35 years. Sixty-4 (96%) patients received liver transplant from deceased donors, whereas 3 (4%) patients received liver allografts from living donors. Five patients underwent simultaneous liver and kidney transplant, and 1 patient had simultaneous liver and heart transplant. The most common indications for liver transplantation were end-stage liver disease due to chronic hepatitis C [n = 19 (28.4%)] and alcoholic liver disease [n = 18 (26.9%)]. Other demographic data and clinical variables are shown in Table 1.
Table 1. Demographic and Clinical Characteristics of 67 Cytomegalovirus-Seronegative Recipients of Liver Allografts from Cytomegalovirus-Seropositive Donors
|Age of patient|| |
| Mean (SD)||49.5 (11.35)|
| Median (IQR)||49.0 (44.0–58.0)|
| Male||50 (74.6%)|
| Female||17 (25.4%)|
|Charlson comorbidity index*|| |
| Mean (SD)||5.6 (1.8)|
| Median (IQR)||5 (4–7)|
|Renal insufficiency*†||6 (9%)|
|Diabetes mellitus*||25 (37.3%)|
|Indication for transplantation‡|| |
| Chronic hepatitis C||19 (28.4%)|
| Alcoholic hepatitis||18 (26.9%)|
| Hepatocellular carcinoma||13 (19.4%)|
| Mycophenolate mofetil||22 (32.8%)|
| Tacrolimus||66 (98.5%)|
| Prednisone||47 (70.1%)|
| Sirolimus||2 (3%)|
|Acute allograft rejection§|| |
| Three months||22 (33%)|
| Six months||25 (37%)|
| One year||27 (40%)|
Antiviral Prophylaxis and CMV Disease
All 67 patients received valganciclovir [n = 58 (87%)] or oral ganciclovir [n = 9 (13%)] prophylaxis. The median duration of antiviral prophylaxis was 92 days [interquartile range (IQR): 91-100; range: 36-171]. No breakthrough CMV disease was observed during the period of antiviral prophylaxis.
During the period following the cessation of antiviral prophylaxis, 19 (28%) patients developed primary CMV disease, including 9 patients with CMV syndrome and 10 patients with tissue-invasive CMV disease [gastrointestinal involvement (n = 8) and hepatitis (n = 2)]. The proportion of CMV disease was comparable between patients who received combined liver and other organ transplant and patients who received liver transplant alone [2 of 6 (33%) versus 17 of 61 (28%)]. Likewise, the incidence of delayed-onset primary CMV disease was comparable between the group of patients who received oral ganciclovir and those who received valganciclovir prophylaxis [22% versus 28% at 1 year after transplantation, respectively, by Kaplan-Meier estimate; hazard ratio (HR) = 0.71; 95% confidence limit (CL): 0.16, 3.06; P = 0.63]. The median time to the diagnosis of CMV disease was 153 days after liver transplantation (range: 71-782 days; IQR: 132-173 days) or 55 days after antiviral prophylaxis was stopped (range: 25-651 days; IQR: 44-77 days). The cumulative incidence of CMV disease after the discontinuation of anti-CMV prophylaxis was 2%, 25%, 27%, 27%, and 29% at 1, 3, 6, 12, and 24 months, respectively. The majority (90%) of cases of CMV disease occurred within 100 days after prophylaxis was stopped. One patient developed primary CMV syndrome at 782 days concurrently with an episode of surgical wound infection. No relapse of CMV disease was observed after a mean of 5.3 weeks (range: 2-12 weeks) of antiviral treatment with IV ganciclovir alone (n = 5), IV ganciclovir followed by valganciclovir (n = 7), valganciclovir alone (n = 6), or IV ganciclovir that was switched to IV foscarnet because of ganciclovir-induced severe neutropenia (n = 1). No case of ganciclovir-resistant CMV was observed.
Associations Between Clinical Variables and CMV Disease
The association between various demographic and clinical variables and the primary outcome of delayed-onset primary CMV disease is presented in Table 2. In this univariate Cox proportional hazard analysis, female gender (HR = 3.2; 95% CL: 1.3, 7.9; P = 0.01), Charlson comorbidity index (HR = 0.71; 95% CL: 0.52, 0.97; P = 0.019), age in decades at the time of liver transplantation (HR = 0.65; 95% CL: 0.45, 0.95: P = 0.03), and diabetes mellitus (HR = 0.076; 95% CL: 0.01, 0.57; P < 0.001) were associated with delayed-onset primary CMV disease. In particular, patients younger than 40 years were at higher risk of delayed-onset primary CMV disease (HR = 3.57; 95% CL: 1.35, 9.45; P = 0.02). In separate bivariate models that accounted for age, gender, and Charlson comorbidity index, the negative association between diabetes mellitus and delayed-onset primary CMV disease remained significant (P < 0.05). In contrast, chronic hepatitis C was not significantly associated with increased risk of delayed-onset primary CMV disease (HR = 0.86; 95% CL: 0.31, 2.39; P = 0.77). Likewise, acute allograft rejection was not significantly associated with subsequent CMV disease (HR = 1.76; 95% CL: 0.71, 4.33; P = 0.21). Only a few patients received lymphocyte-depleting agents such as muromonab-CD3 or antithymocyte globulin, so a meaningful analysis of their potential association with CMV disease was not performed. None of the specific maintenance immunosuppressive drugs was significantly associated with CMV disease. However, the use of prednisone (HR = 2.70; 95% CL: 0.79, 9.27; P = 0.080) or mycophenolate mofetil (HR = 2.11; 95% CL: 0.85, 5.20; P = 0.11) at the end of CMV prophylaxis had a nonsignificant trend toward an increased risk of delayed-onset primary CMV disease.
Table 2. Clinical and Demographic Variables Assessed for Association with Delayed-Onset Primary Cytomegalovirus Disease After Liver Transplantation
|Age by decade||0.65||0.45||0.95||0.03|
|Charlson comorbidity index||0.71||0.52||0.97||0.02|
|Mycophenolate mofetil use||2.11||0.85||5.20||0.11|
|Chronic hepatitis C||0.86||0.31||2.39||0.77|
CMV Disease and Patient and Allograft Survival
During the median follow-up time of 3.3 years (range: 0.8-5.9 years), 8 patients either died (n = 5) or developed allograft failure that required retransplantation (n = 3). The cumulative incidence of death or allograft loss with Kaplan-Meier estimate was 3.0%, 4.7%, and 4.7% at 1, 2, and 3 years after liver transplantation, respectively. According to a time-dependent Cox proportional hazard model, patients with CMV disease had a combined allograft loss and mortality risk that was not significantly different from that of patients who did not develop CMV disease (HR = 1.5; 95% CL 0.36, 6.36; P = 0.58). Similarly, liver transplant recipients with tissue-invasive CMV disease did not have a higher rate of allograft loss or mortality when compared to all other patients who did not have tissue-invasive CMV disease (HR = 1.4; 95% CL 0.28, 7.27; P = 0.67).
In this study, which is a reflection of the contemporary practice of antiviral prophylaxis, primary CMV disease remains a common complication among CMV D+/R− liver transplant recipients. In these patients, the onset of primary CMV disease occurred within 3 months after completion of antiviral prophylaxis. Female liver transplant recipients and younger patients were significantly more likely to develop delayed-onset primary CMV disease, whereas patients with diabetes had a lower risk. These findings, which summarize our 5-year clinical observations, reflect the current state of CMV management after liver transplantation. Accordingly, the information contained in this report may serve to guide clinicians in advising CMV D+/R− liver transplant recipients of their ongoing risk of primary CMV disease during the immediate period after antiviral prophylaxis is stopped. Moreover, these findings emphasize the need for defining better strategies for CMV prevention after liver transplantation.
The current guideline for the prevention of CMV disease recommends that all CMV D+/R− liver transplant recipients should receive antiviral prophylaxis for 3 months after transplantation.14 However, as previously reported by others,8, 16 we also demonstrate that this strategy does not completely prevent CMV disease in a considerable number of high-risk CMV D+/R− patients. Indeed, in one study,8 breakthrough CMV disease was even observed during valganciclovir prophylaxis. In our study, however, there were no cases of breakthrough CMV disease during antiviral prophylaxis, but soon thereafter, primary CMV disease occurred in roughly 1 of every 4 CMV D+/R− liver transplant recipients. In order to prevent delayed-onset primary CMV disease and its consequences, a strategy of CMV surveillance and preemptive treatment has been proposed in high-risk patients after a period of antiviral prophylaxis.17 However, this is a logistically difficult approach,17 and our experience with this strategy has been disappointing (unpublished data for kidney transplant recipients). Nonetheless, if this approach is pursued, frequent CMV surveillance is suggested during the first 3 months after antiviral prophylaxis is stopped, which is the time period when the vast majority of delayed-onset primary CMV disease occurs.
A strategy of prolonging the duration of antiviral prophylaxis in CMV D+/R− liver transplant recipients has also been proposed to prevent delayed-onset CMV disease.18 However, this approach may not be optimal because delayed-onset primary CMV disease has been reported to occur even in patients who received up to 5 years of prophylaxis.19 Moreover, prolonged antiviral exposure may increase the risk of antiviral drug resistance.20 Hence, a more judicious use of prolonged antiviral prophylaxis in only a select group of patients who may benefit the most is needed. In this context, this study aimed to determine who among the CMV D+/R− liver transplant recipients are at highest risk of delayed-onset primary CMV disease following antiviral prophylaxis. Similarly to Freeman and colleagues,11 we observed that female liver transplant recipients were at a higher risk of delayed-onset CMV disease. The underlying mechanism for our observations is not entirely evident, although this could potentially be explained by a more favorable environment for CMV in estrogen-rich conditions.21, 22 Further studies are needed to determine whether female liver transplant recipients will need more aggressive prophylaxis. Surprisingly, we also observed that younger patients were at a higher risk, whereas patients with diabetes mellitus had a lower risk of delayed-onset primary CMV disease. The mechanisms underlying these observations are also not clearly apparent. Previous studies have alluded to the relationship between CMV and posttransplant diabetes.23–25 Indeed, a negative correlation between CMV and diabetes has been described in islet26 and simultaneous pancreas and kidney27–29 transplantation. In contrast to the study by Freeman and colleagues, we did not observe a significant association between renal insufficiency and CMV disease. It is possible that the inclusion of a large number of kidney transplant recipients in the study of Freeman and colleagues could have accounted for this difference in our findings. In this regard, we emphasize one of the major strengths of this study, which is the analysis of a homogeneous population of high-risk CMV D+/R− liver transplant recipients, and by doing so, we were able to limit the confounders that may have been associated specifically with other nonliver organ transplantation.
The association between acute allograft rejection and CMV disease is a well-described phenomenon in transplantation.12 Surprisingly, our study did not demonstrate such an association. This lack of association is most likely accounted for by our clinical practice of providing additional antiviral prophylaxis to CMV D+/R− liver transplant recipients during the time and for 4 weeks after the treatment of acute allograft rejection. This practice was adapted in 2001 when we initially observed the significant association between acute rejection and delayed-onset CMV disease in liver (and kidney) transplant recipients.12 This practice is currently supported by the American Society of Transplantation guidelines, which recommend antiviral prophylaxis to patients who receive antilymphocyte therapies for the treatment of acute rejection.14 Nonetheless, the association between CMV disease and the degree of immunosuppression remains evident in this study. Although specific immunosuppressive drugs were not significantly associated with CMV disease, we observed that liver transplant recipients who were receiving mycophenolate mofetil and prednisone during the last day of antiviral prophylaxis remained at a higher risk, albeit nonsignificant, of developing delayed-onset primary CMV disease. Although these associations were not statistically significant, we believe that our findings still imply that patients with a higher net state of immunosuppression are more likely to develop delayed-onset primary CMV disease.
In this study, delayed-onset primary CMV disease was not significantly associated with the combined outcome of allograft loss and mortality. As previously suggested by Hellinger and colleagues,30 this finding would imply that the adverse effects of CMV on the outcomes after liver transplantation have been diminished in the era of antiviral prophylaxis. Indeed, a meta-analysis by Hodson and colleagues31 demonstrated that antiviral prophylaxis reduced not only the incidence of CMV disease but the overall mortality as well. More recently, Limaye and colleagues5, 9, 10 suggested that liver transplant recipients with CMV disease have a 4-fold to 5-fold increased risk of 1-year mortality compared to those who do not develop CMV disease. We believe that the lack of significant association between CMV disease and allograft and patient survival could also be explained by the overall low incidence of allograft loss and death in our cohort. Our cohort had a composite allograft and patient survival of 97.0% and 95.3% at 1 and 3 years, respectively [which is higher than the national rate32 and those of previous reports33 (that is, 68.1% at 3 years)].
In conclusion, primary CMV disease occurs at a delayed onset in a relatively high proportion of D+/R− liver transplant recipients despite the use of standard 3-month antiviral prophylaxis with oral ganciclovir or valganciclovir. The clinical presentation is predominantly CMV syndrome or gastrointestinal CMV disease. Female patients, younger patients, and those who remain on mycophenolate mofetil and prednisone at the end of prophylaxis were found to be at a higher risk of delayed-onset primary CMV disease. These groups of patients may therefore benefit from a better strategy for CMV prevention. Whether this would entail prolonging prophylaxis or a more intensive surveillance with the use of CMV PCR will need to be addressed in future prospective studies. Although no significant association was observed between delayed-onset primary CMV disease and allograft and patient survival in this study, the morbidity associated with this illness should warrant a better strategy for CMV disease prevention. These collective observations should serve as a guide to clinicians in their ongoing care of high-risk CMV D+/R− liver transplant recipients.
We thank Ms. Teresa Hoff for her secretarial support and the members of the Liver Transplant Team and Transplant Infectious Diseases Focus Group for their care of these patients.