Considerable improvement over time has occurred in 1-year survival rates after liver transplantation (LT), but subsequent long-term patient and graft survival has not improved.1-3 2,4
Whereas pretransplant factors affecting 1-year outcome are well established,5,6 7 8 9 10
The causes for graft loss and mortality before and after the first posttransplant year differ markedly1 2,11 12 13 14
Identification of early predictors of long-term outcomes in HCV-negative LT recipients could serve for risk stratification of patients and to guide long-term care. Early surrogate markers of long-term outcome can also become important endpoints in future clinical trials.
We analyzed our over 30-year LT experience with a nationwide multicenter long-term follow-up with the aim of determining prognostic factors for multiple key outcomes beyond the first posttransplant year in HCV-negative patients. We also studied differential effects of immunosuppression regimen.
MATERIALS AND METHODS
The study included all HCV-negative adult patients with LT in Finland between 1982 and 2013 and at least 1-year graft survival. Exclusions were age at LT less than 18 (n = 102), less than 1-year follow-up (n = 198), and HCV seropositivity (n = 27). All LTs in Finland are performed at Helsinki University Hospital. All grafts were from brain-dead donors. Long-term follow-up of patients is routinely at 3- to 4-month intervals at one of 20 specialized secondary- or tertiary-care gastroenterological clinics. There are also scheduled follow-up visits at the transplant clinic every 1-3 years in the long term.
The transplant clinic maintains the Finnish LT registry with accurate clinical and follow-up data on virtually all LT patients in Finland; patient adherence to long-term follow-up in Finland is extremely high (3 of 925 LT patients lost to follow-up). Follow-up data recorded in the registry come from both scheduled follow-up visits and hospitalizations at either the local hospital or transplant clinic. By national agreement, local hospitals send a copy of patient records to the transplant clinic at least twice annually and whenever an LT patient is admitted.
Data are entered to the registry by a transplant coordinator, after verification by the senior transplant physician, at the time of listing for LT, at the time of transplantation, and annually thereafter, and after the occurrence of predefined events such as re-transplantation, rejection, infection, or death.
All rejections were biopsy-confirmed and evaluated according to standard criteria.15
All severe infection episodes that require hospital-based investigations or treatment at any hospital in Finland are recorded in the LT registry according to a standardized procedure described in detail previously.16 17,18
Part of the Finnish LT registry has undergone formal quality control; results showed a completeness rate of 99.5% and a consistency rate of 99.3%.19
Cancer cases were identified through linkage of the Finnish LT registry with the population-based Finnish Cancer Registry, with the unique national personal identity code used as a key. The cancer registration in Finland is virtually complete.20
Immunosuppression and Rejection Treatment
All patients received calcineurin-inhibitor (CNI)-based initial immunosuppression. The majority received and was maintained on cyclosporine (Cya) in combination with an antimetabolite, azathioprine (AZA) being the primary choice until 2006, and mycophenolate (MMF) thereafter. Methylprednisolone was given initially, and, when feasible, steroid withdrawal was attempted within 12 months postoperatively except in patients with underlying autoimmune liver disease. The typical daily dose of methylprednisolone when used long term was 2-4 mg.
Tacrolimus (TAC)-based initial immunosuppression was administered to 125 patients, mostly as part of randomized trials. In addition, some patients were switched to TAC during the first year either because of Cya-related side effects (n = 22), such as hypertrichosis or gingival hyperplasia (which are unlikely to affect prognosis), or because of immunologic instability (early acute cellular rejection [ACR], unspecified elevations in liver enzymes, or severe rejection) (n = 117). Target trough levels after the first posttransplant year have varied over time and depending on the number of concomitant immunosuppressive agents for Cya, from 70 to 175 ng/mL, and for TAC, from 5 to 10 ng/mL. Antibody induction therapy has been used in only a few patients as part of trials.
The initial treatment of ACR was with a 5-day steroid course (methylprednisolone 3 mg/kg/day). Steroid-resistant ACRs were treated with OKT3 monoclonal antibodies or in some cases with ATG polyclonal antibodies.
Statistical Methods
Data were analyzed with IBM SPSS Statistics for Windows, version 22.0 (Armonk, NY: IBM Corp.). Outcomes after the first posttransplant year that were studied separately were combined graft loss or death, ACR and chronic (ductopenic) rejection, de novo cancer, and infections. For each of these four outcomes, we performed separate univariate Cox regression analyses testing for the factors detailed in Table 1 . A potential calendar-era effect was accounted for by validating the multivariate predictors in the subset of patients who underwent transplantation after year 2000, and including era as dependent variable in regression analyses. Three eras (1982-1999, 2000-2007, 2008-2013) were chosen based on clinical relevance (tacrolimus [TAC] introduced around year 2000, and MMF in mid-2000s) and to produce subgroups of fairly similar size.
TABLE 1: Patient characteristics before liver transplantation (LT) and at 1 year posttransplant
Physiological MELD scores were calculated with plasma creatinine capped at 350 μmol/L, also if hemodialysis. GFR was estimated using the modification of diet in renal disease (MDRD)-4 equation.
Factors statistically significant on univariate analysis were considered in multivariate Cox regression analyses. Separate Cox regression analyses were performed to test the effects on the four aforementioned outcomes of type of immunosuppression at 1 year posttransplant by means of the following comparisons: Cya to TAC, any antimetabolite to no use, type of antimetabolite (none vs. AZA vs. MMF), and steroid use to no use.
As TAC and MMF have been available chiefly after year 2000, analyses regarding immunosuppression type were restricted to LTs after 2000. Furthermore, to adjust for potential selection bias from early immunologic instability, which could severely confound comparisons, immunosuppression analyses also excluded patients who during the first year had either multiple ACR episodes, antibody-treated ACR, or chronic rejection, or who at 1 year posttransplant had an elevated alanine aminotransferase (>50 U/L) or alkaline phosphatase (>105 U/L). The remaining group represented a well-defined subgroup of immunologically stable patients.
We also studied the effect of the 1-year immunosuppression regimen on the change in GFR from 1 to 10 years stratified by GFR at 1 year; these analyses were performed in the entire cohort without the exclusion criteria for immunologic instability or year of LT. Differences in GFR between groups were calculated by the Mann-Whitney or Kruskal-Wallis test.
Survival curves were by Kaplan-Meier methodology and differences in survival tested by the log-rank test. Correlations were calculated by the Pearson correlation. P values <0.05 were considered statistically significant.
RESULTS
The study included 686 LTs in 631 patients (Table 1 ). During the mean follow-up of 9.2 years (SD 6.1, range 1-29 years, 6311 person-years), 154 grafts were lost >1 year posttransplant. Of these 154 graft losses, 33 (21%) led to re-transplantation, and 121 (79%) were due to patient death (of which 24% had chronic graft dysfunction). Causes for graft loss and death are shown in Table S1, SDC , https://links.lww.com/TP/B229
Patient and graft survival rates in the study cohort (all patients alive at 1 year) were respectively 92 and 89% at 5 years, 83 and 79% at 10 years, and 64 and 59% at 20, and there was no significant temporal improvement in these rates.
Late Graft Loss and Death
Univariate predictors of combined graft loss or death were male gender (P = 0.001), HCC (P = 0.009) or CCC (P < 0.001) in the native liver, the combination female donor–male recipient (P = 0.005), re-LT due to rejection (P = 0.022), low BMI (P = 0.008), lack of hypertension (P < 0.001), low 1-year GFR (P = 0.005), high ALT (P < 0.001), ALP (P < 0.001), bilirubin (P < 0.001), low hemoglobin (P = 0.007), and CMV (P = 0.002), or other infection (P < 0.001) before 1 year.
Multivariate predictors were male gender, HCC or CCC, lack of hypertension, low 1-year GFR, high ALP, and CMV or other infection before 1 year (Table 2 ). All of these factors retained statistical significance in the subgroup of LTs after year 2000.
TABLE 2: Multivariate factors associated with the four different outcomes beyond the first posttransplant year by Cox regression analysis
Late Rejection
Fifty-five patients (8%) had ACR after the first year (mean 3.6 years posttransplant, SD 2.9). Eighteen patients (2.6%) developed chronic rejection after the first year (mean 5.5 years posttransplant, SD 3.7); of these, six (33%) had experienced ACR within the first year and six (33%) also developed ACR after the first year. Altogether, 11 (61%) of 18 patients with chronic rejection experienced ACR at some point. Of late chronic rejections, nine (50%) led to re-transplantation and another six (33%) to death.
Univariate predictors of ACR or chronic rejection as a combined outcome were young age (P = 0.008), antibody-treated early ACR (P = 0.024), ALT (P = 0.001), ALP (P = 0.001), and CMV infection before 1 year (P = 0.047), and the combination female donor–male recipient (P = 0.025). In multivariate analysis, young age, early CMV infection, and ALP remained significant (Table 2 ); in the subgroup of LTs after 2000, CMV infection (P = 0.049) and ALP (P = 0.015) remained significant.
Cancer
One hundred fourteen patients developed 137 de novo non-hepatic malignancies after the first posttransplant year, including 60 skin cancers and 12 posttransplant lymphoproliferative diseases. Eighteen patients had multiple malignancies after the first year, mostly multiple skin cancers. In addition, 25 patients had a history of pretransplant non-hepatic cancer, and 11 were diagnosed with de novo cancer within the first posttransplant year.
Univariate predictors of de novo cancer after the first years were higher age (P = 0.002), male gender (P = 0.006), alcoholic cirrhosis (P = 0.017) or chronic autoimmune hepatitis (P = 0.03) as the underlying disease, and HCC in the native liver (P = 0.042). In multivariate analysis, the effect of age, gender, and autoimmune hepatitis remained significant (Table 2 ). In the subgroup of LTs after year 2000, male gender (P = 0.019) and autoimmune hepatitis (P = 0.048) remained significant.
Late Infections
Sixteen patients (2%) experienced a CMV infection and 248 patients (36%) a non-CMV infection after the first post-LT year.
Univariate predictors for late CMV and non-CMV infections combined were higher age (P = 0.009), LT before year 2000 (P = 0.004), diabetes (P = 0.006), lack of hypertension (P = 0.025), the combination female donor–male recipient (P = 0.012), and non-CMV infection within the first post-LT year (P < 0.001). All of these factors remained significant in multivariate analysis (Table 2 ) and also in the subgroup of LTs after year 2000.
Influences of Immunosuppression Regimen
The impact of immunosuppression type at 1 year on the various long-term outcomes was studied in a subgroup of 476 immunologically stable patients transplanted after year 2000. In this group, rates of continuing the same drug at 5 and 10 years posttransplant were, for Cya, 93 and 91%; for TAC, 91 and 85%; for AZA, 57 and 42%; for MMF, 76 and 45%; for absent antimetabolite, 82 and 74%; and for steroids, 47 and 33%. As only five patients were using mTOR inhibitors at 1 year, these were not studied further.
The trough level of Cya or TAC at 1 year or respective mean trough level between years 1 and 3 did not significantly correlate with trough levels at 5 or 10 years posttransplant.
A trend towards better combined graft and patient survival emerged with antimetabolite use compared to no use (P = 0.049) (Figure 1 and Table 3 ). CNI trough levels at various time points did not differ according to antimetabolite use (Figure S1, SDC , https://links.lww.com/TP/B229 P = 0.02).
FIGURE 1: Combined graft and patient survival in a subgroup of immunologically stable patients who underwent transplantation after year 2000 according to type of (A) calcineurin inhibitor, (B) antimetabolite, and (C) steroid use at 1 year posttransplant.
TABLE 3: Association between various immunosuppression medications at 1 year and the four study outcomes by Cox regression analyses in a subgroup of immunologically stable patients transplanted after year 2000
There were no differences on either survival or other outcomes between MMF and AZA, Cya and TAC, or steroid use and no steroid use (Figure 1 and Table 3 ), and no difference in survival between patients with initial TAC versus those switched to TAC within the first year (P = 0.17). Moreover, the number of agents used or type of combination did not significantly impact survival (Figure S2, SDC , https://links.lww.com/TP/B229
Immunosuppression Regimen and Long-Term Kidney Function
Type of CNI or antimetabolite at 1 year had no significant effect on the average change in GFR from posttransplant year 1 to year 10 (Figure 2 ). No effect of mean Cya or TAC trough level year 1-3 or dose of MMF or AZA was observed either (data not shown).
FIGURE 2: Change in estimated glomerular filtration rate (GFR) from posttransplant year 1 to year 10 according to (A) calcineurin-inhibitor type and (B) antimetabolite at 1 year. Bars represent means and vertical lines standard deviations. P values calculated by the Mann-Whitney or Kruskal-Wallis test.
Post Hoc Analyses on ALP
ALP at 1 year was above the upper limit of normal among 30% of patients both in the TAC and Cya groups. The link between elevated ALP at 1 year and late all-cause graft loss or death was directly related to the magnitude of ALP elevation, and emerged at ALP >1.5 times the upper limit of normal following a latency of several years (Figure 3 ). This link remained significant also in the subgroup of patients otherwise immunologically stable during the first posttransplant year (ie, absence of multiple or severe ACR episodes and absence of chronic rejection during first year) (Figure 3 ), among non-PSC patients (P < 0.001), non-PSC/PBC patients (P < 0.001), and separately among TAC (P < 0.001) and Cya users (P < 0.001, all by log-rank test). Of patients who lost their graft or died secondary to chronic rejection between 1 and 10 years after LT, 77% had an elevated ALP (>105 U/L) at 1 year post-LT. By receiver-operating characteristics testing, area-under-the-curve (AUC) value for ALP at 1 year in differentiating 10-year combined graft loss and death from rejection was 0.81 (95% CI 0.71-0.90, P < 0.001) and from any cause 0.63 (95% CI 0.57-0.70, P < 0.001). Among patients aged under 50, respective AUC values for ALP were 0.85 (95% CI 0.72-0.98, P = 0.001) and 0.71 (95% CI 0.62-0.80, P < 0.001).
FIGURE 3: The influence of alkaline phosphatase at 1 year on combined graft and patient survival >1 year after liver transplantation among (A) all patients and (B) immunologically stable patients (absence of severe or multiple acute rejection episodes or chronic rejection during first year).
The 10-year cumulative rate of chronic rejection with versus without an ALP >1.5 times the upper limit of normal was 10 and 2.4%, respectively.
Simple Score to Predict Long-Term Survival
The number of the following factors present at 1 year post-LT: any infection, ALP >1.5 times the upper limit of normal, native-liver HCC/CCC, and GFR <45 mL/min was able to stratify long-term survival (Figure 4 ).
FIGURE 4: Combined patient and graft survival according to the number of the following risk factors known at 1 year posttransplant: any infection within first year, GFR <45 mL/min at 1 year, native-liver HCC/CCC, and ALP >1.5 times the upper limit of normal at 1 year.
DISCUSSION
Several important observations emerged in this comprehensive nationwide study analyzing early predictors of multiple long-term outcomes in HCV-negative LT recipients. First, pretransplant patient liver status (ascites, encephalopathy, variceal bleeding, MELD score) had no influence on outcomes beyond the first posttransplant year. Second, chief risk factors for the combined endpoint of graft loss and death >1 year posttransplant were pretransplant liver or biliary cancer, poor renal function, early posttransplant infections, and elevated markers of cholestasis. ALP, in particular, predicted both late graft loss and incident rejection. Therefore, ALP deserves routine monitoring in the long term, and investigations if elevated. Third, the absent influence of type of CNI or type of antimetabolite on incident late ACR or chronic rejection implies that, in general, the immunosuppression regimen beyond the first posttransplant year is likely best chosen based on its toxicity profile instead of on its immunopotency. Fourth, an apparently almost universal need to reduce the level of long-term immunosuppression might especially concern patients with early infections, given the observed association between such infections and combined late graft loss and death. On the other hand, the link between early CMV infections and late graft rejection emphasizes the importance of preventing such early CMV infections by effective antiviral prophylaxis. Fifth, a simple score consisting of four reproducible variables known at 1 year post-LT showed good ability to discriminate long-term patient/graft survival. This score needs external validation before its possible use in clinical practice to personalize long-term follow-up.
Strengths of our study include a nationwide and complete coverage of LTs and a multicenter follow-up, extending up to 29 years, which can practically never be achieved by randomized trials. In addition, patient adherence to follow-up is extremely high in Finland with only 3 of our country’s all 925 LT patients lost to follow-up. The Finnish LT registry data comprises an exceptional number of variables, both at baseline and during follow-up, and this enabled extensive adjustments in risk factor analyses. Moreover, using multiple study endpoints allowed comprehensive evaluation of the relevance and potential opposing effects of risk factors. We were able to extract virtually complete outcome data with regards to rejection episodes, graft loss, mortality, and cancer. In addition, setting the study baseline to 1 year post-LT permitted taking into account relevant clinical issues emerging during the first posttransplant year; this approach better reflects clinical practice where long-term care is guided by dynamic clinical data. It is specifically the survival after the first posttransplant year that has universally seen no improvement over recent decades.1-3
Comparisons to previous risk-factor analyses regarding long-term outcomes are hampered by their inclusion of HCV-positive patients,11,21-24 21,23 25,26 11,22-24 11,22,24 11,22,24 11,22 22 22
Potential explanations for the observed predictors include cancer recurrence in HCC/CCC, cardiovascular mortality in renal dysfunction, and over-immunosuppression among patients with early infections. Extreme caution is necessary when interpreting the observed impact of hypertension because the Finnish LT registry lacks well-defined criteria for hypertension; nonetheless, an equivalent impact was seen in a previous study,22
ALP—an early prognostic marker in our study—may increase secondary to various biliary, vascular, immunologic, and infectious conditions,27 28 29
Although late chronic rejection is very rare under modern immunosuppression therapy, chronic immune-mediated graft injury may assume increasing relevance due to the growing interest in immunosuppression minimization.30 2,31 32 33 34
Our findings favor the addition of an antimetabolite to CNI-based maintenance immunosuppression among patients with pretransplant liver cancer. Although not clearly seen in our study, antimetabolite use indeed enables a reduction of CNI dosage, and a dose-dependent relationship has previously been described between CNI use and HCC recurrence and de novo cancer.35-38 39
Study limitations include the inability, in a retrospective registry-based study, to fully account for all factors that might have influenced the choice of immunosuppression regimen. Also, the dynamics of liver biochemistry could not be fully accounted for, although liver enzymes in most cases have well stabilized by 1 year posttransplant. We were unable to adjust analyses for compliance problems, which are likely an extremely important factor especially regarding late rejection, but compliance among our LT recipients is considered excellent. The Finnish LT registry lacks well-defined criteria for hypertension and diabetes. Registry data do not distinguish clearly between permanent diabetes and transient posttransplant hyperglycemia; this likely attenuated the acknowledged detrimental effects of diabetes. Too small numbers prevented analyses of mTOR inhibitors.
Our population of HCV-negative patients included more PBC and PSC, and less alcoholic cirrhosis, hepatitis B, and HCC than at many centers, which may limit generalizability.
In conclusion, patients with pretransplant liver or biliary cancer, poor renal function, early posttransplant infections, or elevated ALP represent a high-risk group that warrants closer long-term follow-up. Early interventions directed towards these potentially modifiable risk factors might improve the universally stagnant >1-year posttransplant survival. ALP deserves to be routinely monitored, and an elevated ALP merit further investigations and possibly escalation of immunosuppression, but further study is warranted. A tendency observed towards improved long-term outcome with antimetabolite use may suffer from bias inherent to any retrospective study.
ACKNOWLEDGMENTS
This study is indebted all of those who collaborate in maintaining the Finnish Liver Transplant Registry, and Eero Pukkala for providing data from the Finnish Cancer Registry.
REFERENCES
1. Adam R, Karam V, Delvart V, et al.; All contributing centers (
www.eltr.org ); European Liver and Intestine Transplant Association (ELITA). Evolution of indications and results of liver transplantation in Europe. A report from the European Liver Transplant Registry (ELTR).
J Hepatol . 2012; 57: 675–688.
2. Åberg F, Gissler M, Karlsen TH, et al. Differences in long-term survival among liver transplant recipients and the general population: a population-based Nordic study.
Hepatology . 2015; 61: 668–677.
3. Lodhi SA, Lamb KE, Meier-Kriesche HU. Solid organ allograft survival improvement in the United States: the long-term does not mirror the dramatic short-term success.
Am J Transplant . 2011; 11: 1226–1235.
4. Barber K, Blackwell J, Collett D, et al.; UK Transplant Liver Advisory Group. Life expectancy of adult liver allograft recipients in the UK.
Gut . 2007; 56: 279–282.
5. Burroughs AK, Sabin CA, Rolles K, et al.; European Liver Transplant Association. 3-month and 12-month mortality after first liver transplant in adults in Europe: predictive models for outcome.
Lancet . 2006; 367: 225–232.
6. Thuluvath PJ, Yoo HY, Thompson RE. A model to predict survival at one month, one year, and five years after liver transplantation based on pretransplant clinical characteristics.
Liver Transpl . 2003; 9: 527–532.
7. Charlton MR. Improving long-term outcomes after liver transplantation.
Clin Liver Dis . 2014; 18: 717–730.
8. Forman LM, Lewis JD, Berlin JA, et al. The association between hepatitis C infection and survival after orthotopic liver transplantation.
Gastroenterology . 2002; 122: 889–896.
9. Futagawa Y, Terasaki PI, Waki K, et al. No improvement in long-term liver transplant graft survival in the last decade: an analysis of the UNOS data.
Am J Transplant . 2006; 6: 1398–1406.
10. Dumortier J, Boillot O, Scoazec JY. Natural history, treatment and prevention of hepatitis C recurrence after liver transplantation: past, present and future.
World J Gastroenterol . 2014; 20: 11069–11079.
11. Watt KD, Pedersen RA, Kremers WK, et al. Evolution of causes and risk factors for mortality post-liver transplant: results of the NIDDK long-term follow-up study.
Am J Transplant . 2010; 10: 1420–1427.
12. Haddad EM, McAlister VC, Renouf E, et al. Cyclosporin versus tacrolimus for liver transplanted patients.
Cochrane Database Syst Rev . 2006: CD005161.
13. Lucey MR, Terrault N, Ojo L, et al. Long-term management of the successful adult liver transplant: 2012 practice guideline by the American Association for the Study of Liver Diseases and the American Society of Transplantation.
Liver Transpl . 2013; 19: 3–26.
14. Geissler EK, Schlitt HJ. Immunosuppression for liver transplantation.
Gut . 2009; 58: 452–463.
15. Banff schema for grading liver allograft rejection: an international consensus document.
Hepatology . 1997; 25: 658–663.
16. Aberg F, Mäkisalo H, Höckerstedt K, et al. Infectious complications more than 1 year after liver transplantation: a 3-decade nationwide experience.
Am J Transplant . 2011; 11: 287–295.
17. Lautenschlager I. CMV infection, diagnosis and antiviral strategies after liver transplantation.
Transpl Int . 2009; 22: 1031–1040.
18. Ljungman P, Griffiths P, Paya C. Definitions of cytomegalovirus infection and disease in transplant recipients.
Clin Infect Dis . 2002; 34: 1094–1097.
19. Karam V, Gunson B, Roggen F, et al.; European Liver Transplant Association. Quality control of the European Liver Transplant Registry: results of audit visits to the contributing centers.
Transplantation . 2003; 75: 2167–2173.
20. Teppo L, Pukkala E, Lehtonen M. Data quality and quality control of a population-based cancer registry. Experience in Finland.
Acta Oncol . 1994; 33: 365–369.
21. Gelson W, Hoare M, Dawwas MF, et al. The pattern of late mortality in liver transplant recipients in the United Kingdom.
Transplantation . 2011; 91: 1240–1244.
22. Pfitzmann R, Nüssler NC, Hippler-Benscheidt M, et al. Long-term results after liver transplantation.
Transpl Int . 2008; 21: 234–246.
23. Busuttil RW, Farmer DG, Yersiz H, et al. Analysis of long-term outcomes of 3200 liver transplantations over two decades: a single-center experience.
Ann Surg . 2005; 241: 905–916.
24. Schoening WN, Buescher N, Rademacher S, et al. Twenty-year longitudinal follow-up after orthotopic liver transplantation: a single-center experience of 313 consecutive cases.
Am J Transplant . 2013; 13: 2384–2394.
25. Watt KD, Dierkhising R, Heimbach JK, et al. Impact of sirolimus and tacrolimus on mortality and graft loss in liver transplant recipients with or without hepatitis C virus: an analysis of the Scientific Registry of Transplant Recipients Database.
Liver Transpl . 2012; 18: 1029–1036.
26. Wiesner RH, Shorr JS, Steffen BJ, et al. Mycophenolate mofetil combination therapy improves long-term outcomes after liver transplantation in patients with and without hepatitis C.
Liver Transpl . 2005; 11: 750–759.
27. Mason AL, Montano-Loza AJ. Systematic investigation of elevated cholestatic enzymes during the third posttransplant month.
Liver Transpl . 2013; 19( Suppl 2): S23–S30.
28. Levitsky J, Fiel MI, Norvell JP, et al. Risk for immune-mediated graft dysfunction in liver transplant recipients with recurrent HCV infection treated with pegylated interferon.
Gastroenterology . 2012; 142: 1132–1139.e1.
29. Neil DA, Hubscher SG. Histologic and biochemical changes during the evolution of chronic rejection of liver allografts.
Hepatology . 2002; 35: 639–651.
30. Londoño MC, Rimola A, O’Grady J, et al. Immunosuppression minimization vs. complete drug withdrawal in liver transplantation.
J Hepatol . 2013; 59: 872–879.
31. Åberg F, Isoniemi H, Höckerstedt K. Long-term results of liver transplantation.
Scand J Surg . 2011; 100: 14–21.
32. Barbier L, Garcia S, Cros J, et al. Assessment of chronic rejection in liver graft recipients receiving immunosuppression with low-dose calcineurin inhibitors.
J Hepatol . 2013; 59: 1223–1230.
33. Benítez C, Londoño MC, Miquel R, et al. Prospective multicenter clinical trial of immunosuppressive drug withdrawal in stable adult liver transplant recipients.
Hepatology . 2013; 58: 1824–1835.
34. Tisone G, Orlando G, Cardillo A, et al. Complete weaning off immunosuppression in HCV liver transplant recipients is feasible and favourably impacts on the progression of disease recurrence.
J Hepatol . 2006; 44: 702–709.
35. Dantal J, Hourmant M, Cantarovich D, et al. Effect of long-term immunosuppression in kidney-graft recipients on cancer incidence: randomised comparison of two cyclosporin regimens.
Lancet . 1998; 351: 623–628.
36. Vivarelli M, Cucchetti A, La Barba G, et al. Liver transplantation for hepatocellular carcinoma under calcineurin inhibitors: reassessment of risk factors for tumor recurrence.
Ann Surg . 2008; 248: 857–862.
37. Rodríguez-Perálvarez M, Tsochatzis E, Naveas MC, et al. Reduced exposure to calcineurin inhibitors early after liver transplantation prevents recurrence of hepatocellular carcinoma.
J Hepatol . 2013; 59: 1193–1199.
38. Carenco C, Assenat E, Faure S, et al. Tacrolimus and the risk of solid cancers after liver transplant: a dose effect relationship.
Am J Transplant . 2015; 15: 678–686.
39. Germani G, Pleguezuelo M, Villamil F, et al. Azathioprine in liver transplantation: a reevaluation of its use and a comparison with mycophenolate mofetil.
Am J Transplant . 2009; 9: 1725–1731.
