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* From the Divisions of Infectious Diseases (Dr. Brumble), Mayo Clinic, Jacksonville, FL; and Allergy, Pulmonary, and Critical Care Medicine (Drs. Milstone, Loyd, and Ely), Cardiac and Thoracic Surgery (Dr. Pierson), Preventive Medicine and Biostatistics (Dr. Gautam), and Infectious Diseases (Dr. Dummer), Vanderbilt University Medical Center, Nashville, TN.
Correspondence to: J. Stephen Dummer, MD, Division of Infectious Diseases, Vanderbilt University Medical Center, 911 Oxford House, Nashville, TN 37232; e-mail: Stephen.Dummer{at}mcmail.vanderbilt.edu
| Abstract |
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Methods: CMV detection was by shell vial culture or IgG seroconversion; after 1996, CMV detection was by blood antigenemia. The diagnosis of CMV disease also required a typical clinical syndrome or pathologic evidence of CMV. The main outcome was the actuarial incidence of CMV infection and disease. In order to account for the effect of other important risk factors for CMV infection, the time to CMV infection and disease was also studied as dependant variables in a Cox proportional-hazard analysis, with the delayed regimen and other important risk factors as independent variables.
Results: The delayed regimen reduced the actuarial incidence of CMV infection from 80 to 48% (p < 0.001) and CMV disease from 31 to 10% (p < 0.01). No seropositive patient receiving the delayed regimen developed CMV disease. Twelve of the 54 patients in the study group required additional IV antiviral treatment, but the total use of ganciclovir averaged only 18 days per patient. In a Cox proportional-hazards model, the use of delayed ganciclovir was the only factor that showed a significant association with freedom from CMV infection (hazard ratio [HR], 0.43; 95% confidence interval [CI], 0.24 to 0.75; p = 0.003) and CMV disease (HR, 0.29; 95% CI, 0.10 to 0.86; p = 0.03).
Conclusion: A regimen of CMV prophylaxis employing 2 weeks of IV ganciclovir initiated 3 to 4 weeks after lung transplantation followed by virologic monitoring and preemptive therapy as needed provides good protection against CMV disease.
Key Words: cytomegalovirus ganciclovir lung transplantation prophylaxis transplantation
| Introduction |
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3 months).5
6
7
8
However,
prolonged administration of IV ganciclovir is expensive and may be
associated with bone marrow suppression, line infection, or ganciclovir
resistance.5
6
Since CMV disease rarely occurs before the
second month after transplantation, we postulated that ganciclovir
could be introduced late in the first posttransplant month, thereby
focusing antiviral management during the period of highest risk. In
1994, we introduced a standard 2-week course of parenteral ganciclovir
beginning 21 to 28 days after lung transplantation in CMV-seropositive
patients. The same regimen is also used in seronegative patients with
seropositive donors, but combined with doses of CMV hyperimmune
globulin administered at 2, 4, 6, and 8 weeks after transplantation. In
order to assess the efficacy of this delayed ganciclovir prophylaxis,
we reviewed the occurrence of CMV infection and disease in patients
receiving this regimen in comparison with patients who underwent
transplantation earlier without receiving the regimen. A multivariate
analysis was then performed to assess the impact of the delayed regimen
on the occurrence of CMV infection and disease with other risk factors,
such as patients CMV serostatus and the intensity of
immunosuppression. | Materials and Methods |
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Immunosuppression
All patients received preoperative immunosuppression consisting
of single doses of parenteral cyclosporine, 5 to 7 mg/kg, and
azathioprine, 4 mg/kg. A dose of 500 mg of parenteral
methylprednisolone was administered in the operating room after release
of the pulmonary arterial clamp, followed by three doses of 125 mg of
methylprednisolone administered every 8 h. After the operation,
all patients were treated with triple immunosuppression (cyclosporine,
azathioprine, and methylprednisolone). In addition, all patients
received 7 to 14 days (mean, 11 days) of induction therapy with
Nashville rabbit antithymocyte serum or globulin (N-RATS/G; Applied
Medical Research; Nashville, TN). Two patients did not tolerate
N-RATS/G and received equine antithymocyte globulin (ATGAM; Pharmacia
and Upjohn; Kalamazoo, MI). Acute rejection episodes were
treated with daily methylprednisolone, 1 g, for 3 consecutive days
or an oral prednisone taper. A few patients who had rejection episodes
unresponsive to steroid therapy and some patients with obliterative
bronchiolitis were treated with a subsequent course of N-RATS/G or
muromonab-CD3 (Orthoclone OKT3; Ortho Biotech; Raritan, NJ).
Delayed CMV Prophylaxis
Prior to September 1994, the standard CMV prophylaxis of our
center was oral acyclovir, 800 mg tid, until 6 months after
transplantation. Of the 33 patients who served as historical control
subjects, 28 patients received no ganciclovir prophylaxis, whereas the
other 5 patients received a limited course of the drug (15 to 29 days)
in the first posttransplant month. Subsequently, a regimen of delayed
ganciclovir prophylaxis was established whereby the standard acyclovir
prophylaxis was interrupted at 21 to 28 days after transplantation for
a 2-week course of parenteral ganciclovir. This interval was chosen
rather than a specific day as a practical measure to allow drug
initiation on a scheduled clinic day. The delayed ganciclovir
prophylaxis regimen consisted of 1 week of induction therapy (5 mg/kg
q12h) followed by maintenance dosing for an additional 7 days (5 mg/kg
q24h). The doses were reduced according to the recommendations of the
manufacturer in patients with renal dysfunction. Whenever possible, the
ganciclovir was administered outside the hospital through a
peripherally inserted central catheter. After completion of ganciclovir
prophylaxis, patients were monitored virologically and some received
additional courses of preemptive antiviral therapy. These courses were
administered either because the patients were receiving IV
antirejection therapy or had positive virologic findings (shell vial
culture or blood antigenemia). Twelve of the 54 patients in the study
group received additional courses of preemptive IV antiviral therapy, 5
patients for positive virologic findings and 7 patients during
treatment for acute rejection. Three of these patients also received
foscarnet because they had persistent or rising antigenemia while
receiving ganciclovir. The mean duration of all IV antiviral therapy
(including the standard 14-day course) for the 54 patients was 18 days
during the first 100 postoperative days. When not receiving IV
antiviral therapy, all patients received oral acyclovir prophylaxis,
800 mg tid, until 6 months after transplantation. Patients who were
seronegative for CMV and had seropositive donors (donor-positive,
recipient-negative patients) also received 100 mg/kg of parenteral CMV
hyperimmune globulin (MedImmune; Gaithersburg, MD) at postoperative
weeks 2, 4, 6, and 8.
Laboratory Monitoring
Before transplantation, CMV IgG titers were determined for all
donors and recipients. Follow-up titers were performed in some patients
at the discretion of the attending pulmonary physician. All
patients were also screened for active CMV infection on the day of
transplantation by viral urine culture. Posttransplant surveillance
consisted of weekly blood and urine cultures for 12 weeks followed by
cultures every 2 to 4 weeks until 6 months. Thereafter, cultures were
obtained for clinical indications. In 1996, CMV blood cultures were
replaced with testing for CMV antigenemia (Biotest Diagnostics
Corporation; Denville, NJ). Specimens obtained from either bronchoscopy
or endoscopy were evaluated for CMV by histology, immunoperoxidase
studies, and culture.
Definitions and Monitoring
CMV infection was defined as the presence of either a
positive culture finding for CMV from any site, or positive blood CMV
antigenemia. Additionally, patients with a fourfold or greater rise in
IgG antibody to CMV were deemed to be infected. IgM antibodies were not
used to diagnose infection. CMV disease was diagnosed only
in patients with CMV infection and was defined as: (1) the presence of
pathognomonic cytopathic changes consistent with CMV on biopsy
specimens or cytology, or (2) a typical viral syndrome consisting of
fever for > 3 days without another source and with at least one of
the following: atypical lymphocytosis (> 3%), leukopenia (WBC count
< 4,000/µL), thrombocytopenia (platelet count < 100,000/µL),
and/or elevated transaminases (alanine transaminase > 40 IU).
Additional monitoring (either bronchoscopy or endoscopy) was performed
as clinically indicated. Bronchoscopy with BAL and biopsy was performed
for clinical indications, such as a fall in FEV1,
fever associated with pulmonary infiltrates, or new, unexplained
hypoxemia. Transbronchial biopsy specimens were graded for acute
rejection and obliterative bronchiolitis according to the International
Society for Heart and Lung Transplantation
criteria.9
Outcomes and Variables Assessed
The primary outcomes in this study were the incidence of CMV
infection and disease in the first year after transplantation.
Pretransplant variables that were evaluated include age, gender,
pretransplant diagnosis, type of lung transplant, and donor and
recipient CMV serostatus. Posttransplant variables included length of
initial posttransplant intubation, ischemia time, number of proved
rejection episodes, cumulative dose of steroids used to treat
rejection, days of antithymocyte globulin administered, and whether the
patient received delayed ganciclovir prophylaxis.
Statistical Analysis
2 or Fishers Exact Test were used to
compare categorical data, and the Students t test was used
for continuous variables. Differences were considered significant if
the p value was < 0.05. A Cox proportional-hazard analysis was
performed using the times to CMV infection and disease as end points.
Patients were
censored
for loss of follow-up due to any cause. All covariates (Tables 1
, 2
) were entered into the model in a forward stepwise fashion with
p < 0.15 needed to enter. Survival curves were generated by the
Kaplan-Meier method, and analysis was performed using the log-rank
test. All analyses were performed using statistical software (SAS
version 7.0; SAS Institute; Cary, NC).
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| Results |
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Kaplan-Meier Plots
The times to CMV infection and CMV disease in patients who either
received or did not receive delayed ganciclovir prophylaxis are shown
in Figures 1
,
2
. Our analysis shows that our prophylactic regimen was associated with a
reduced actuarial incidence of CMV infection from 80 to 48% and CMV
disease from 31 to 10% in the first year after transplantation. The
curves are significantly different by log-rank test (p < 0.001 and
p = 0.01, respectively). No deaths due to CMV disease occurred in the
delayed ganciclovir group. One patient in the control group had severe
primary graft failure, and had fever and CMV inclusions on BAL sample
shortly before her death from respiratory failure 43 days after
transplantation. The actuarial freedom from bronchiolitis obliterans
was not statistically different between the two study groups (curves
not shown; p = 0.94 by log-rank test).
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3 days was
of borderline statistical significance (p = 0.07).
CMV Disease: Univariate Analysis
Table 3
shows the same variables analyzed in relation to the development of CMV
disease. In this analysis, donor-positive, recipient-negative
serostatus (p = 0.06) and the use of N-RATS/G induction therapy for
> 10 days (p = 0.05) were statistically associated with the
development of CMV disease. Again, the use of delayed ganciclovir
prophylaxis was inversely associated with the development of CMV
disease (p = 0.02).
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| Discussion |
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3 months
to suppress CMV infection.5
6
8
These lengthier regimens
have had a greater impact on the rates of CMV disease than shorter
courses, but they are expensive, potentially dangerous, and not
completely effective.5
In 1994, our center developed a
delayed, abbreviated ganciclovir regimen. Based on the absence of CMV
disease in the first transplant month at our center, we thought that
delaying the introduction of ganciclovir until 3 to 4 weeks after
transplantation would not only be safe, but would potentially permit
the host to develop an immune response against CMV. In theory, this
emerging immune response could decrease the chance of CMV disease
occurring after ganciclovir was discontinued. This early prophylaxis
was coupled to a strategy of clinical and virologic monitoring, by
which patients could receive additional pre-emptive courses of
ganciclovir if they were treated for rejection or if they became
positive for CMV by virologic assays. Our analysis shows that our prophylactic regimen reduced the actuarial incidence of CMV infection from 80 to 48% and the incidence of CMV disease from 31 to 10% in the first year after transplantation (Fig 1 , 2) . Remarkably, no seropositive patient who received the regimen had CMV disease develop. Finally, the total exposure to IV antiviral therapy was only 18 days per patient in the first 100 days after transplantation, the time period during which patients are at greatest risk for CMV. This finding illustrates that it is not necessary to administer lengthy ganciclovir prophylaxis to most patients, if prophylaxis is timed carefully and frequent virologic monitoring is performed to detect recurrent infection.
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Our prophylactic regimen did not consist solely of ganciclovir. We also used high-dose oral acyclovir when patients were not receiving ganciclovir. CMV-seronegative patients with seropositive donors also received CMV Ig. Both acyclovir and CMV Ig have a demonstrated impact on CMV disease.17 18 However, their antiviral activity is far less potent than ganciclovir. Indeed, CMV disease in transplant populations did not really come under excellent control until ganciclovir became available as a therapeutic and prophylactic agent. Thus, it is likely that the outcomes we describe are primarily due to the ganciclovir regimen.
Our strategy couples a short course of ganciclovir prophylaxis with subsequent preemptive therapy based on antigenemia testing. It may be possible to obtain similar results by omitting the prophylaxis and using a purely preemptive strategy. When we first introduced our regimen, viral cultures were our only tool to monitor patients, but they were not thought to be adequately sensitive. Despite the availability of better monitoring tools, we still adhere to our regimen because it provides certain protection for patients at a time when they are highly vulnerable to CMV and a laboratory error could lead to a severe, yet preventable illness.
Two classic risk factors for CMV disease have been determined in solid-organ transplant recipients: the occurrence of primary infection and the use of high doses of immunosuppression, especially antithymocyte globulin.19 The results of our univariate analysis are consistent with this, in that CMV disease was more common in patients who received a long course of antithymocyte globulin, and there was a strong trend to significance in CMV-seronegative patients with positive donors. The failure to detect significance in the multivariate analysis is likely only due to the relatively small numbers of patients and the greater stringency of that analysis.
Our study suffers the usual limitations of a retrospective analysis, and it would be desirable to confirm the results in a prospective trial. To date, however, no large, prospective, randomized trial of antiviral prophylaxis has been performed in lung recipients. It is unlikely that untreated patients or placebo recipients would be used in any such future trial due to the high morbidity of CMV infection in lung transplantation. Yet, the low rate of CMV disease, as seen with current prophylactic and preemptive strategies (including ours), means that it would be necessary to enroll very large numbers of patients in future trials to show differences in disease outcomes, if patients in both arms of the study were receiving effective antiviral management. Thus, future trials may be limited to showing equivalence between conventional and new antiviral compounds, or assessing pharmacoeconomic end points. Antiviral trials would also be useful to evaluate the impact of different regimens on long-term outcomes such as graft survival or the incidence of bronchiolitis obliterans. Bronchiolitis obliterans is the most important complication of lung transplantation, and a number of studies9 11 13 20 have linked its occurrence to CMV infection. For instance, Duncan and colleagues10 found that the actuarial prevalence of chronic rejection at 2 years was 74% in lung transplant recipients with a history of biopsy-proven CMV pneumonitis compared with 22% among CMV-negative patients (p < 0.038). However, it is not known whether this association is causal or whether CMV prophylaxis can have an impact on the incidence of chronic rejection.14 Our study provides evidence that an abbreviated "minimalist" approach to CMV prophylaxis is effective and safe, but it did not show any effect on the incidence of bronchiolitis obliterans.
Although the delayed ganciclovir regimen has been effective in our population, its ability to suppress CMV may vary depending on the intensity of immunosuppression, and this in turn may differ between institutions. The success of this regimen is predicated on the absence of CMV disease in the first posttransplant month. We have discovered that some patients who are receiving immunosuppression to treat idiopathic pulmonary fibrosis already have positive urine culture findings for CMV on the day of transplantation.21 Delayed prophylaxis would not be appropriate for such patients, and they should receive ganciclovir as soon as their infection is diagnosed. Performance of a rapid, sensitive test for CMV infection, such as a shell vial culture of urine, is indicated on the day of transplantation in anyone who has been receiving immunosuppressive medication. Even in the majority of patients without CMV infection at the time of transplantation, it is probably advisable to monitor for CMV during the first posttransplant month as insurance against a rare occurrence. In addition to a viral urine culture on the day of transplantation, we perform blood antigenemia at 2, 3, and 4 weeks after transplantation.
Our study provides evidence that ganciclovir prophylaxis in lung transplant recipients can be delayed and does not need to be prolonged in most patients. Current virologic monitoring makes it possible to follow patients safely and individualize their antiviral management after an initial brief course of prophylaxis.22 It is not known whether a more intense CMV prophylactic regimen could improve long-term outcomes such as graft survival. This is an important issue that should be addressed in future trials.
| Footnotes |
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Received for publication February 22, 2001. Accepted for publication July 26, 2001.
| References |
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This article has been cited by other articles:
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A. P. Milstone, L. M. Brumble, J. Barnes, W. Estes, J. E. Loyd, R. N. Pierson III, and S. Dummer A single-season prospective study of respiratory viral infections in lung transplant recipients Eur. Respir. J., July 1, 2006; 28(1): 131 - 137. [Abstract] [Full Text] [PDF] |
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C. Schroder, F. Scholl, E. Daon, A. Goodwin, W. H. Frist, J. R. Roberts, K. G. Christian, M. Ninan, A. P. Milstone, J. E. Loyd, et al. A modified bronchial anastomosis technique for lung transplantation Ann. Thorac. Surg., June 1, 2003; 75(6): 1697 - 1704. [Abstract] [Full Text] [PDF] |
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