Influence of CYP3A5 Genetic Polymorphism on Long-Term Renal Function in Chinese Kidney Transplant Recipients Using Limited Sampling Strategy and Abbreviated Area Under the Curve for Tacrolimus Monitoring.

INTRODUCTION: Although the association between CYP3A5 gene polymorphism and tacrolimus dosing requirements was well established, the impact on how CYP3A5 genotype affects the acute rejection and long-term renal function in patients who received kidney transplants and were treated with tacrolimus remained controversial. DESIGN: Sixty-seven Chinese patients with kidney transplants receiving de novo tacrolimus-based immunosuppressive therapy with known CYP3A5 genotype were divided into 2 groups. Those with at least 1 CYP3A5*1 allele were CYP3A5 expressers while homozygotes for the mutant allele CYP3A5*3 were nonexpressers. Instead of trough level, our center used abbreviated area under the curve for tacrolimus monitoring. Primary outcome was the long-term renal function between both groups while secondary outcomes included the weight-adjusted daily tacrolimus dose, graft survival, incidence of biopsy-proven acute rejection (BPAR), opportunistic infection, and cancer. RESULTS: Thirty-five (52.2%) patients were CYP3A5 expressers while 32 were nonexpressers. Mean daily tacrolimus dose in the CYP3A5 expressers and nonexpressers was 0.08 (0.03) and 0.05 (0.02) mg/kg, respectively (P < .01). Starting from 1-month posttransplant, the renal function was comparable between both groups, which persisted up to 10-year. Ten patients experienced BPAR rejection and there was no significant difference in the rejection-free survival between both groups (P = .87). There was also no significant difference in the death-censored graft survival between both groups (P = .86). Finally, the incidence of opportunistic infection and posttransplant cancer was similar between them. DISCUSSION: There was no significant difference in renal function, graft survival, and acute rejection between CYP3A5 expressers and nonexpressers.

Impact of CYP3A5 Genetic Polymorphism on Intrapatient Variability of Tacrolimus Exposure in Chinese Kidney Transplant Recipients.

BACKGROUND: Although high tacrolimus (FK) intrapatient variability (IPV) was shown to be associated with poor graft outcome in kidney transplant recipients (KTRs), it is uncertain whether there is any association between the CYP3A5 genotype and IPV of FK concentrations. Instead of trough level, we use calculated abbreviated AUC0-12 to investigate the impact of CYP3A5 genetic polymorphism on IPV of FK pharmacokinetics. METHODS: We conducted a retrospective, single-center study of 86 adult Chinese KTRs with known CYP3A5 genotype. Coefficient of variation (CV) was used for the quantification of FK IPV. CV of dose-normalized FK AUC0-12 was calculated and was compared between the CYP3A5 expresser group and nonexpresser group. RESULTS: Forty-one patients (47.7%) were classified as CYP3A5 expressers while 45 were nonexpressers. No significant differences in the baseline characteristics were found between expressers and nonexpressers. CYP3A5 expressers required 1.8 times higher FK dose compared with the nonexpressers. There was no significant difference in the FK CV between CYP3A5 expressers (18.2 ± 7.5%) and nonexpressers (16.7 ± 5.7%) (P = .31). CONCLUSION: The IPV of FK exposure was not associated with CYP3A5 genotype in stable KTRs. Further studies should focus on other factors such as medication nonadherence, which may explain FK IPV.

No evidence for progressive deterioration in stimulated insulin secretion in renal transplant recipients after 12years tacrolimus exposure.

AIMS: Tacrolimus (Tac) inhibits insulin secretion in a Tac-trough blood level dependent way early post-transplant in renal transplant recipients (Rtx). It is unknown whether long-term exposure results into a progressive beta cells dysfunction. METHODS: Two independent cohorts of Tac-treated non-diabetic Rtx, previously participating in glucose metabolism studies using intravenous Glucose Tolerance Test (ivGTT) were included: Fifty-eight Rtx were tested by ivGTT cross-sectional between 0.25 and 12.6years post-transplant. Factors related to glucose metabolism parameters were explored by multilinear regression analysis. Eighteen non-diabetic Rtx tested by ivGTT 6months post-transplant were retested at 12years. The glucose metabolism outcome parameters were also adjusted according to the results of the cross-sectional study. RESULTS: Multivariate analysis showed 'Age', 'BMI' and 'use of steroids' to be significantly related, in different combinations, to the glucose metabolism parameters 'insulin resistance', 'fasting insulin level' and 'stimulated insulin secretion'. However 'time on tacrolimus' wasn't related to any parameter. In the longitudinal study, none of the glucose metabolism parameters (either analyzed crude or adjusted) deteriorated clinically or statistically significant. Numerically, 'stimulated insulin secretion' even increased. CONCLUSIONS: Chronic Tac exposure does NOT lead to a progressive decrease in 'stimulated insulin secretion' between 6months and 12years post renal transplant in our population of 18 patients.

Effect of Breakfast on the Exposure of the Once-Daily Tacrolimus Formulation in Stable Kidney Transplant Recipients.

BACKGROUND: The once-daily Tacrolimus formulation (Tac ONCE-DAILY) has to be taken on an empty stomach. This is inconvenient for patients and may hamper compliance. The influence of food intake on the exposure of Tac ONCE-DAILY is unknown in transplant recipients. We compared the pharmacokinetics (PKs) of Tac ONCE-DAILY in stable kidney transplant recipients under fasted and fed conditions. METHODS: In an open-label, single-center, cross-over PK study, 27 stable kidney white transplant recipients (17 male, 10 female) treated with Tac ONCE-DAILY under fasted conditions were enrolled. Two 10-point 24-hour blood concentration time profiles [area under the blood concentration time curve from time 0 to 24 hours (AUC0-24)] were collected under steady state conditions. The primary objective was to investigate the effect of food on the PKs and relative bioavailability of Tac ONCE-DAILY. RESULTS: Twenty-seven stable renal transplant patients provided 1 AUC0-24 under fasted and fed conditions, respectively. AUC0-24, C24, and Cmax, were lower in the fed state and Tmax was 1 hour postponed. The 90% confidence interval ratio (fed: fasted) for AUC0-24 was 0.81-0.91 and for C24 0.82-0.92 (both P < 0.001). The majority (60%) had no significant change, but the change in AUC0-24 ranged from -38% to +29%. One trough level was below the target range after fed intake. CONCLUSIONS: When Tac ONCE-DAILY is ingested with standard continental breakfast, AUC0-24 and C24 decrease overall, with C24 in the therapeutic range in almost all patients. The convenient fed intake could promote therapy adherence. Given the possible significant change in exposure, we advise monitoring of the tacrolimus trough level 1 week after fed ingestion of Tac ONCE-DAILY.

Lower variability in 24-hour exposure during once-daily compared to twice-daily tacrolimus formulation in kidney transplantation.

INTRODUCTION: Tacrolimus has originally been registered as a twice-daily formulation (Prograf, Tac BID), although a once-daily formulation (Advagraf, Tac QD) is also available. A reduced intrapatient variability of Tac Cmin, a surrogate marker for 24-hour drug exposure (AUC0-24), has been suggested. The variability of AUC0-24 has never been studied prospectively yet. The purpose of this study was to investigate the change in intrapatient variability of Tac AUC0-24 after converting from Tac BID to Tac QD. METHODS: Forty renal transplant patients on Tac BID were converted on a 1:1 (mg/mg) basis to Tac QD in an investigator-driven comparative pharmacokinetic (PK) study. AUC0-24 was determined five times before and after conversion. Duplicate samples were collected by the patients themselves using the dried blood spot method. The main outcome measure is the change in intrapatient variability of AUC0-24 expressed as coefficient of variation (CV). Moreover, the influence of Cyp3A5 genotype polymorphism on the change in CV was studied. RESULTS: In total, 400 AUC0-24 profiles were available for analysis. Conversion to Tac QD resulted in a significant improvement in intra-patient CV from 14.1% to 10.9% (P=0.012). Patients with the Cyp3A5*1/*3 genotype (n=11) had a numerically larger improvement in CV than patients with the CYP3A5*3/*3 genotype. CONCLUSION: Intrapatient CV of Tac AUC0-24 improved after converting from Tac BID to Tac QD in stable renal transplant patients, especially in patients with the CYP3A5*1/3 genotype. Given the very strict protocol of this PK study, this improvement is most likely due to the different intrinsic PK properties of Tac QD and Tac BID.

Immunosuppressive regimen and interstitial fibrosis and tubules atrophy at 12 months postrenal transplant.

BACKGROUND AND OBJECTIVES: Chronic renal transplant dysfunction is histopathologically characterized by interstitial fibrosis and tubular atrophy. This study investigated the relative contribution of baseline donor, recipient, and transplant characteristics to interstitial fibrosis and tubular atrophy score at month 12 after renal transplantation. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This retrospective study includes all 109 consecutive recipients with adequate implantation and month 12 biopsies transplanted between April of 2003 and February of 2007. Immunosuppression regimen was tacrolimus and steroids (10 days) plus either sirolimus or mycophenolate mofetil. RESULTS: Average interstitial fibrosis and tubular atrophy score increased from 0.70 to 1.65 (P<0.001). In an adjusted multiple linear regression analysis, interstitial fibrosis and tubular atrophy score at month 12 was significantly related to donor type (donors after cardiac death versus living donor had interstitial fibrosis and tubular atrophy score+0.41, 95% confidence interval=0.05-0.76, P=0.02), baseline interstitial fibrosis and tubular atrophy, and immunosuppression regimen. Because of interaction between the latter two variables (P=0.002), results are given separately: recipients with a baseline interstitial fibrosis and tubular atrophy score of zero had a 0.60 higher score at month 12 (95% confidence interval=0.09-1.10, P=0.02) when mycophenolate mofetil-treated, whereas recipients with a baseline interstitial fibrosis and tubular atrophy score more than zero had a 0.38 higher score at month 12 (95% confidence interval=0.01-0.74, P=0.04) when sirolimus-treated. A higher score at month 12 correlated with a lower estimated GFR (ρ=-0.45, P<0.001). CONCLUSIONS: These findings suggest that histologic assessment of a preimplantation biopsy may guide choice of immunosuppresion to maximize transplant survival and its interaction with type of immunosuppression.

Early loss of peritubular capillaries after kidney transplantation.

Inflammation, interstitial fibrosis (IF), and tubular atrophy (TA) precede chronic transplant dysfunction, which is a major cause of renal allograft loss. There is an association between IF/TA and loss of peritubular capillaries (PTCs) in advanced renal disease, but whether PTC loss occurs in an early stage of chronic transplant dysfunction is unknown. Here, we studied PTC number, IF/TA, inflammation, and renal function in 48 patients who underwent protocol biopsies. Compared with before transplantation, there was a statistically significant loss of PTCs by 3 months after transplantation. Fewer PTCs in the 3-month biopsy correlated with high IF/TA and inflammation scores and predicted lower renal function at 1 year. Predictors of PTC loss during the first 3 months after transplantation included donor type, rejection, donor age, and the number of PTCs at the time of implantation. In conclusion, PTC loss occurs during the first 3 months after renal transplantation, associates with increased IF and TA, and predicts reduced renal function.

Four-year experience with tacrolimus once-daily prolonged release in patients from phase II conversion and de novo kidney, liver, and heart studies.

INTRODUCTION: This study assessed the long-term effects of prolonged-release tacrolimus (Advagraf(®) [Tacrolimus QD]), which has been developed to provide similar efficacy and safety to twice-daily tacrolimus (Prograf(®) [Tacrolimus BID]) with the added benefit of once-daily dosing. METHODS: Adult participants from four phase II de novo (kidney, liver) or Tacrolimus BID to QD conversion (kidney, heart) studies were enrolled into the follow-up study. Patients remained on the immunosuppressive regimen they were receiving on entry, unless medical needs required otherwise. The primary endpoint was patient and graft survival, and secondary endpoints were biopsy-confirmed acute rejection (BPAR) and safety. RESULTS: The full analysis set comprised 240 patients. Tacrolimus mean total daily dose and whole-blood trough levels decreased over time, particularly in de novo patients. At four yr, Kaplan-Meier estimates of patient and graft survival were over 90%. Freedom from BPAR was 90.9/92.6% and 100/87.0% in the de novo kidney/liver and conversion kidney/heart patients, respectively. There were 13 deaths, and 20% patients withdrew from the study, mainly because of adverse events. CONCLUSIONS: The efficacy and safety of Tacrolimus QD was maintained for four yr in kidney, liver, and heart transplant recipients. Therefore, this formulation offers a convenient alternative to Tacrolimus BID.

FK778 attenuates cytomegalovirus-enhanced vein graft intimal hyperplasia in a rat model.

BACKGROUND: Venous grafts are commonly used to treat drug-resistant coronary artery disease, although long-term functionality is limited because of proliferation and migration of smooth muscle cells (SMC). As proliferating SMC are particularly susceptible for the stimulating effects of cytomegalovirus (CMV), we hypothesized that CMV infection may enhance cell proliferation and graft failure. Furthermore, we evaluated the potential of FK778 to prevent intimal hyperplasia. Apart from its antiviral properties, FK778 is a new immunosuppressive agent which may also affect SMC proliferation, making it an interesting drug to prevent (CMV-enhanced) venous graft intimal hyperplasia. METHODS: Epigastric vein-to-common femoral artery interposition grafts were placed in four groups of 10 rats each. Rats received either FK778 (oral treatment, 15 mg/kg), were infected with CMV (1.25 x 10(6) plaque-forming units) or were both treated and infected. RESULTS: CMV infection resulted in a significant increase in intimal and medial cross-sectional area and medial wall thickness of the vein grafts. This effect was diminished by administration of FK778. Moreover, FK778 treatment alone resulted in a significant decrease in neointimal area and percentage of stenosis versus the control group. CONCLUSIONS: These data suggest a role of CMV in venous graft failure. Also, our results suggest a prospective role for the new immunosuppressive drug FK778 in the prevention of (CMV-mediated) vein graft intimal hyperplasia.

Pre-kidney-transplant blood transfusions do not improve transplantation outcome: a Dutch national study.

BACKGROUND: Female renal transplant candidates are prone to be sensitized by prior pregnancies, and undetected historical sensitization might decrease transplantation outcome. Hypothesis of our study was that pre-transplant blood transfusions (PTFs) can elucidate historical sensitization and that the avoidance of the associated antigens can improve transplantation outcome. METHODS: Data from all female non-immunized renal transplant candidates who received a random PTF (rPTF) (n = 620), matched PTF (mPTF) (one HLA-A and B and one HLA-DR match) (n = 86) or donor-specific blood transfusion (DST) (n = 100) between 1996 and 2006 were collected. Complement-dependent cytoxicity was used to detect anti-HLA antibodies. Sensitization and transplantation outcomes after a PTF were analyzed. Non-immunized female renal transplant recipients who did not receive a PTF were used as the control group. RESULTS: In 165 patients, anti-HLA antibodies (IgG) were detected after the PTF. Both historical and primary sensitizations were found. A DST induced donor-specific anti-HLA antibodies in 25% of the DST recipients. Our policy did not improve transplantation outcome in recipients of a kidney from a deceased donor (n = 368) or in recipients of a living donor [DST (n = 49) and mPTF (n = 66)]. CONCLUSIONS: A PTF did elucidate historical sensitization but induce primary sensitization as well. No beneficial effect of PTFs on transplantation outcome was found, and PTFs with the intention to detect historical sensitization are therefore not suggested.

Clinical relevance of pretransplant donor-directed antibodies detected by single antigen beads in highly sensitized renal transplant patients.

BACKGROUND: Highly sensitized (HS) patients (>85% panel-reactive antibodies) have a lower chance of receiving a donor kidney. Within Eurotransplant the Acceptable Mismatch (AM) program was developed to increase the chances of HS patients to receive a crossmatch-negative donor kidney. The standard crossmatch in the AM program is based on complement-dependent cytotoxicity. METHODS: In this study we wanted to determine the clinical relevance of human leukocyte antigen donor-directed antibodies (DDA) detected by the single antigen (SA) bead technique, in the pretransplant sera of HS patients transplanted in our center through the Eurotransplant AM program. RESULTS: From 34 AM patients, 27 were transplanted with 1 to 5 mismatches and 7 received a 0-mismatched graft. From the mismatched patients, retrospectively, 13 proved to possess pretransplant DDA by SA whereas 14 did not. No antibodies were found in the 0-mismatched group. Comparison of the DDA+ and DDA- patients in the human leukocyte antigen-mismatched donor/recipient combinations revealed a trend to an earlier and higher number of rejection episodes in DDA+ patients (P=0.08). No detrimental effect of DDA on graft survival was observed. CONCLUSIONS: This single-center study showed that in the AM program DDA detected by SA, and not by less-sensitive methods, may be related to acute rejection episodes but is not detrimental to long-term graft outcome. These findings question the increasing use of more-sensitive screening techniques for the allocation of organs.

Glucose metabolism before and after conversion from cyclosporine microemulsion to tacrolimus in stable renal recipients.

BACKGROUND: Tacrolimus is more diabetogenic than cyclosporine. However, this difference is only discernible in the first few months after renal transplantation. In randomized trials, investigating the effects of immunosuppression after renal transplantation, no increase in diabetes mellitus has been reported. However, no sensitive technique was used in these trials, so subclinical alteration of glucose metabolism cannot be excluded. METHODS: We, therefore, decided to use an intravenous glucose tolerance test (IV-GTT), to investigate whether conversion from cyclosporine-based immunosuppression, with a median trough level of 120 microg/l, to tacrolimus-based immunosuppression with a median trough level of 6.5 microg/l influences glucose metabolism and whether patients on steroids behave differently from those not on steroids. RESULTS: Thirty stable, non-diabetic patients, transplanted 10 or more years earlier, were converted from cyclosporine to tacrolimus without changing their concomitant medication. IV-GTT's were performed before and 2.5 months after the conversion. Before conversion, 40% of the patients had an abnormal glucose disappearance rate (kG): in 7%, kG was below 0.8 (abnormal range) and in 34%, kG was between 0.8 and 1.2 (indeterminate range). After conversion, stimulated insulin production, kG, HbA1C and fasting glucose did not change significantly. Insulin resistance (HOMA-R) of the whole group increased significantly, mainly due to a rise in HOMA-R in patients on steroids (n = 18). None of these patients developed overt diabetes mellitus. CONCLUSIONS: Some 40% of long-term cyclosporine-treated patients had an abnormal glucose metabolism. Conversion from cyclosporine to tacrolimus does not negatively influence stimulated glucose metabolism or insulin resistance in stable, steroid-free renal transplant recipients. However, in patients receiving steroids, conversion leads to an increase in insulin resistance while insulin output remains the same.

Evaluation of limited sampling strategies for tacrolimus.

OBJECTIVE: In literature, a great diversity of limited sampling strategies (LSS) have been recommended for tacrolimus monitoring, however proper validation of these strategies to accurately predict the area under the time concentration curve (AUC0-12) is limited. The aim of this study was to determine whether these LSS might be useful for AUC prediction of other patient populations. METHODS: The LSS from literature studied were based on regression equations or on Bayesian fitting using MWPHARM 3.50 (Mediware, Groningen, the Netherlands). The performance was evaluated on 24 of these LSS in our population of 37 renal transplant patients with known AUCs. The results were also compared with the predictability of the regression equation based on the trough concentrations C0 and C12 of these 37 patients. Criterion was an absolute prediction error (APE) that differed less than 15% from the complete AUC0-12 calculated by the trapezoidal rule. RESULTS: Thirteen of the 18 (72%) LSS based on regression analysis were capable of predicting at least 90% of the 37 individual AUC0-12 within an APE of 15%. Additionally, all but three LSS examined gave a better prediction of the complete AUC0-12 in comparison with the trough concentrations C0 or C12 (mean 62%). All six LSS based on Bayesian fitting predicted <90% of the 37 complete AUC0-12 correctly (mean 67%). CONCLUSIONS: The present study indicated that implementation of LSS based on regression analysis could produce satisfactory predictions although careful evaluation is necessary.

Tacrolimus pharmacokinetics and pharmacogenetics: influence of adenosine triphosphate-binding cassette B1 (ABCB1) and cytochrome (CYP) 3A polymorphisms.

Tacrolimus, an immunosuppressant used after organ transplantation, has a narrow therapeutic range and its pharmacokinetic variability complicates its daily dose assessment. P-glycoprotein (P-gp), encoded by the adenosine triphosphate-binding cassette B1 (ABCB1) and the cytochrome (CYP) 3A4 and 3A5 enzymes appears to play a role in the tacrolimus metabolism. In the present study, two different renal transplant recipient groups were used to examine the influence of ABCB1 and CYP3A polymorphisms on the daily tacrolimus dose and several pharmacokinetic parameters. In total 63 Caucasian renal transplant recipients divided into 26 early [median (range) of the days since transplantation - 16 (3-74)] and 37 late [median (range) of the days since transplantation - 1465 (453-4128)] post-transplant recipients were genotyped for ABCB1 and CYP3A polymorphisms. The pharmacokinetic parameters of tacrolimus were determined for all renal transplant recipients and correlated with their corresponding genotypes. A significant difference in allele frequencies of the CYP3A4*1B (P = 0.028) and CYP3A5*1 (P = 0.022) alleles was observed between the early and late post-transplant recipient groups. Significantly higher dose-normalized trough levels (dnC(0)), dose-normalized area under the curve (dnAUC(0-12)), and dose-normalized maximum concentration (dnC(max)) were observed for carriers of the CYP3A5*3 variant allele in both renal transplant patient groups. Except for the daily tacrolimus dose (P = 0.025) no significant differences were observed for carriers of the CYP3A4*1B variant allele. Neither the individual ABCB1 polymorphisms nor the ABCB1 haplotypes were associated with any pharmacokinetic parameter. We noticed that patients carrying a CYP3A5*1 allele require a twofold higher tacrolimus dose compared with homozygous carriers of the CYP3A5*3 variant allele to maintain the target dnAUC(0-12). Therefore, genotyping for the CYP3A5*3 variant allele can contribute to a better and more individualized immunosuppressive therapy in transplant patients.

The functional, metabolic, and anabolic responses to exercise training in renal transplant and hemodialysis patients.

BACKGROUND: Exercise intolerance is common in hemodialysis (HD) and renal transplant (RTx) patients and is related to muscle weakness. Its pathogenesis may vary between these groups leading to a different response to exercise. The aim of the study was to compare intrinsic muscular parameters between HD and RTx patients and controls, and to assess the response to exercise training on exercise capacity and muscular structure and function in these groups. METHODS: Quadriceps function (isokinetic dynamometry), body composition (dual-energy x-ray absorptiometry), and vastus lateralis muscle biopsies were analyzed before and after a 12-week lasting training-program in 35 RTx patients, 16 HD patients, and 21 healthy controls. RESULTS: At baseline, myosin heavy chain (MyHC) isoform composition and enzyme activities were not different between the groups. VO2peak and muscle strength improved significantly and comparably over the training-period in RTx, HD patients and controls (p(time)<0.05). The proportion of MyHC type I isoforms decreased (p(time)<0.001) and type IIa MyHC isoforms increased (p(time)<0.05). The 3-hydroxyacyl-CoA-dehydrogenase activity increased (p(time)=0.052). Intrinsic muscular changes were not significantly different between groups. In the HD group, changes in lean body mass were significantly related to changes in muscle insulin-like growth factor (IGF)-II and IGF binding protein-3. CONCLUSIONS: Abnormalities in metabolic enzyme activities or muscle fiber redistribution do not appear to be involved in muscle dysfunction in RTx and HD patients. Exercise training has comparable beneficial effects on functional and intrinsic muscular parameters in RTx patients, HD patients, and controls. In HD patients, the anabolic response to exercise training is related to changes in the muscle IGF system.

High rejection rate during calcineurin inhibitor-free and early steroid withdrawal immunosuppression in renal transplantation.

Morbidity and mortality due to cardiovascular disease are major problems after renal transplantation. The effects of three immunosuppressive protocols on cardiovascular end points were investigated in a single-center, randomized, parallel (1-1-1) group. Acute rejection was a secondary safety endpoint. Groups were as follows: group one, tacrolimus+sirolimus; group two, tacrolimus+mycophenolate mofetil (MMF); group three, sirolimus+MMF+daclizumab. All groups received two days methylprednisolone only. The Ethical Committee demanded an interim analysis when 50% of the patients were included. In this analysis, 54 patients with a median follow-up of 9.2 months were studied. The Kaplan-Meyer analysis showed a difference in rejection free survival between group one (82%) and group three (34%, P=0.03) and between groups one and two (tacrolimus-based, 76%) and group three (calcineurin-free, 34%, P=0.04). Calcineurin-free immunosuppression with two days of steroids only showed an unacceptable high incidence of acute rejection and re-rejection, and the study had to be stopped.

Nonadherence with immunosuppressive drugs: U.S. compared with European kidney transplant recipients.

BACKGROUND: System factors increasingly are suggested as important yet understudied correlates of nonadherence. OBJECTIVE: To explore the relationship between healthcare system and prevalence of nonadherence with immunosuppressive regimen by studying variation in nonadherence between European and US kidney transplant recipients and as well as nonadherence in European countries. METHODS: We performed a secondary data analysis on data collected in 3 independent cross-sectional studies using comparable methodology including patients from the United States, the Netherlands, Belgium, and Switzerland. Nonadherence was measured using 1 item of the Siegal questionnaire. Patients were categorized as nonadherent if they reported missing a dose of immunosuppression in the last 4 weeks. Analyses were performed by multiple mixed logistic regression, with center as a random effect and clinical and demographical differences between groups as fixed effects. RESULTS: 1563 U.S. and 614 European patients from 3 different countries (Belgium [n=187], the Netherlands [n=85], and Switzerland [n=342]) were included. Prevalence of nonadherence in the United States and Europe was 19.3% and 13.2.%, respectively. This higher nonadherence in US patients was confirmed in a multiple logistic regression analysis (OR = 1.78; 95% CI, 1.10-2.89). Nonadherence differed between Belgium (16%) and the Netherlands (14.1%) (OR = 0.27; 95% CI, 0.09-0.80) and between Belgium and Switzerland (11.4%; OR = 0.17; 95% CI, 0.0-0.42). CONCLUSION: This is the first study showing differences in prevalence of nonadherence between European and US patients and among European patients. Further research should aim at unraveling the dynamics explaining these differences.

Three-year observational follow-up of a multicenter, randomized trial on tacrolimus-based therapy with withdrawal of steroids or mycophenolate mofetil after renal transplant.

BACKGROUND: The challenge in renal transplantation is to improve long-term patient and graft survival without increasing early acute rejection by minimizing immunosuppression. METHODS: This multicenter, observational study investigated the effects of withdrawal of steroids or mycophenolate mofetil (MMF) from a tacrolimus-based triple regimen (tac/MMF/steroids) 3 months posttransplant at 3 years; no additional interventions or assessments were undertaken. Adult patients, included in the intent-to-treat population of the THOMAS study, participated. Patient and graft survival, adverse events, rejection episodes, and immunosuppressive and concomitant medications were assessed. RESULTS: Data at Year 3 was available for 718 patients (triple therapy, n=237; steroid stop, n=235; MMF stop, n=246). The original randomized regimen was maintained in 45.6% of patients in the triple, 62.6% in the steroid stop, and 53.9% in the MMF stop groups. Graft survival rates were 88.1% (triple), 86.4% (steroid stop), and 85.8% (MMF stop); patient survival was 96.1%, 95.9%, and 95.7%, respectively. The incidence of biopsy-proven acute rejection was similar in all groups between Month 7 and Year 3: 1.2% (triple), 2.0% (steroid stop) and 2.0% (MMF stop). Patients in the steroid stop group had less hypertension and significantly lower mean total cholesterol and LDL-cholesterol at Year 3 compared with Month 3 (P=0.02). Median serum creatinine levels remained stable throughout the follow-up and were comparable between groups. CONCLUSION: Immunosuppression minimization initiated at Month 3 was maintained at Year 3 in over half of the patients. Steroid withdrawal was advantageous in reducing the cardiovascular risk factors hyperlipidemia, hypertension and diabetes mellitus. Renal function was stable in all groups.