Immunosuppression in elderly renal transplant recipients: are current regimens too aggressive?

Comparison of kidney allograft survival in the Eurotransplant senior program after changing the allocation criteria in 2010-A single center experience

Aims

The European Senior Program (ESP) aims to avoid waiting list competition between younger and elderly patients applying for renal transplantation. By listing patients ≥65 years on a separate waiting list and locally allocating of grafts ≥65 years exclusively to this cohort, waiting and cold ischemia times are predicted to be shortened, potentially resulting in improved kidney transplantation outcomes. This study compared a historic cohort of renal transplant recipients being simultaneously listed on the general and the ESP waiting lists with a collective exclusively listed on the ESP list in terms of surrogates of the transplantation outcome.

Methods

Total 151 eligible patients ≥ 65 years from Münster transplant Center, Germany, between 1999 and 2014 were included. Graft function, graft and patient survival were compared using surrogate markers of short- and long-term graft function. Patients were grouped according to their time of transplantation.

Results

Recipients and donors in the newESP (nESP) cohort were significantly older (69.6 ± 3.5 years vs 67.1 ± 2 years, p<0.05; 72.0 ± 5.0 years vs 70.3 ± 5.0 years, p = 0.039), had significantly shorter dialysis vintage (19.6 ± 21.7 months vs 60.2 ± 28.1 months, p<0.001) and suffered from significantly more comorbidities (2.2 ± 0.9 vs 1.8 ± 0.8, p = 0.009) than the historic cohort (HC). Five-year death-censored graft survival was better than in the HC, but 5-year graft and patient survival were better in the ESP cohort. After 2005, cold ischemia time between groups was comparable. nESP grafts showed more primary function and significantly better long-term graft function 18 months after transplantation and onwards.

Conclusion

nESP recipients received significantly older grafts, but experienced significantly shorter time on dialysis. Cold ischemia times were comparable, but graft function in the nESP cohort was significantly better in the long term.

Assessment of infectious complications in elderly kidney transplant recipients receiving induction with anti-thymocyte globulin vs basiliximab

BACKGROUND

Elderly transplant recipients experience lower rates of acute rejection with higher rates of infectious complications compared to their younger counterparts. While less intensive immunosuppression may be preferable, there are no recommendations for depleting versus non-depleting induction strategies. We sought to compare infectious complications between anti-thymocyte globulin (ATG) and basiliximab (IL2RA) induction in elderly kidney transplant recipients (KTRs).

METHODS

We reviewed 146 KTRs ≥65 years receiving ATG or IL2RA induction. Per institution protocol, ATG was administered to patients with the following characteristics, irrespective of age: African American (AA), PRA ≥20%, and/or re-transplantation. Infectious complications (bacterial, viral, and invasive fungal) at 1 year were compared.

RESULTS

There were significantly more AA, deceased donors, and sensitized KTRs in the ATG group, reflecting criteria for induction agent. ATG KTRs experienced higher rates of overall infectious complications (77% vs 56%, P = .01), driven by increased bacterial (54% vs 39%, P = .08) and viral infections (51% vs 35%, P = .05). Urinary tract infections (UTIs) and CMV in particular occurred at high rates among ATG patients (46% and 32%, respectively). In multivariate analysis, the only independent risk factor associated with increased risk for infection was induction with ATG (adjusted HR 1.71 [95% CI 1.04-2.83], P = .04). Overall rates of immunologic outcomes were low.

CONCLUSION

Elderly KTRs receiving ATG are at an increased risk for infectious complications, largely attributed to high rates of UTIs and CMV. Additional strategies aimed at mitigating these complications in elderly patients requiring ATG may be beneficial.

Personalized immunosuppression in elderly renal transplant recipients

The number of elderly people has increased considerably over the last decades, due to a rising life expectancy and ageing populations. As a result, an increased number of elderly with end-stage-renal-disease are diagnosed, for which the preferred treatment is renal transplantation. Over the past years the awareness of the elderly as a specific patient population has grown, which increases the importance of research in this group. Elderly patients often receive kidneys from elderly donors while younger donor kidneys are preferentially reserved for younger recipients. Although the rate of acute rejection after transplantation is lower in the elderly, these rejections may lead to graft loss more frequently, as kidneys from elderly donors have marginal reserve capacity. To prevent acute rejection, immunosuppressive therapy is needed. On the other hand, elderly patients have a higher risk to die from infectious complications, and thus less immunosuppression would be preferable. Immunosuppressive treatment in the elderly is complicated further by changes in the pharmacokinetics and pharmacodynamics, with increasing age. Adjustments in standard immunosuppressive regimes are therefore suggested for this population. An unmet need in transplantation medicine is a tool to guide a personalized approach to immunosuppression. Recently several promising biomarkers that identify injury to the graft at an early stage or predict acute rejection have been identified. Unfortunately, none of these biomarkers were tested specifically in the elderly. We believe there is an urgent need to perform clinical trials investigating novel immunosuppressive regimens in conjunction with biomarker studies in this specific population.

Sirolimus Associated with Tacrolimus at Low Doses in Elderly Kidney Transplant Patients: A Prospective Randomized Controlled Trial

OBJECTIVES

There is no consensus on the best immunosuppressive regimen for elderly renal transplant recipients. The objective of this study was to assess cytomegalovirus infection incidence and kidney transplant outcomes in elderly recipients treated with mammalian target of rapamycin inhibitors sirolimus/ tacrolimus at low doses compared with those receiving tacrolimus/mycophenolate sodium.

MATERIALS AND METHODS

In this single-center prospective randomized study (Trial Registration No. NCT02683291), kidney transplant recipients over 60 years of age were randomly allocated into 2 groups: tacrolimus-sirolimus (21 patients) and tacrolimus-mycophenolate (23 patients). Cytomegalovirus infection rate and patient survival, biopsy-proven acute rejection, and renal function at 12 months were assessed.

RESULTS

Cytomegalovirus infection rate was higher in the mycophenolate group (60.9%) than in the sirolimus group (16.7%; P = .004). The rates of biopsy-proven acute rejection, patient survival, graft survival, and estimated glomerular filtration rate over 12 months did not significantly differ between groups.

CONCLUSIONS

The incidence of cytomegalovirus infection was significantly lower in the sirolimus group. The use of tacrolimus combined with sirolimus in elderly kidney transplant recipients is safe.

The pharmacokinetics and pharmacodynamics of mycophenolate mofetil in younger and elderly renal transplant recipients

AIMS

Elderly transplant recipients have a lower incidence of acute rejection, and a higher risk to die from infectious complications. A potential cause may be differences in the pharmacokinetics (PK) or pharmacodynamics (PD) of the immunosuppressive drugs they are taking. This study was designed to comprehensively evaluate the influence of age on the PK and PD of mycophenolic acid (MPA).

METHODS

In this study the PK and PD of MPA was studied in 26 elderly and 54 younger renal transplant recipients treated with mycophenolate mofetil and tacrolimus. Patients were sampled repetitively, both before and during the first 6 months after kidney transplantation. Age-related variability in MPA PK, baseline IMPDH activity, as well as MPA-induced IMPDH inhibition were studied.

RESULTS

The IMPDH activity pre-transplantation did not differ between elderly and younger patients. Neither IMPDH activity pre-transplantation nor maximum IMPDH inhibition was significantly correlated with the patients' age. The area under the MPA plasma concentration-time curve (AUC_0-12h ) and the area under the effect (IMPDH activity)-time curve (AEC_0-12h ) from 0 to 12 h were also not significantly different between the two groups. We found no significant differences in EC₅₀ and E_max between elderly and younger patients.

CONCLUSIONS

Age did not significantly affect the PK or PD of MPA. It is unlikely that the lower incidence of acute rejection in elderly patients, or the higher risk to die from a severe infection in elderly patients is due to different handling of MPA in the elderly.

Immunosuppression in the elderly renal allograft recipient: a systematic review

BACKGROUND

The Elderly are the fastest growing part of kidney transplant recipients. The best immunosuppressive strategy is unknown.

METHODS

We performed a systematic search of randomized controlled trials and observational studies focused on safety and efficacy of different immunosuppression strategies in elderly kidney recipients. Data extraction and risk of bias evaluation were systematically performed.

RESULTS

Ten studies were included: 2 randomized clinical trials and 8 observational. A marginal benefit was found for early renal function with delayed tacrolimus or complete tacrolimus avoidance using mycophenolate mofetil (MMF). Observational cohort studies looked at different antibody induction strategies, calcineurin-inhibitors based maintenance immunosuppression, calcineurin-inhibitor-free sirolimus-based therapy and use of MMF versus azathioprine. Treatment with interleukin-2 receptor antibody induction, calcineurin-inhibitor minimization with MMF and steroid minimization is advisable in the low immunologic risk elderly recipient, considering the increased risk of toxicities, infection and malignancies. In the high immunologic risk elderly recipient, taking into account the morbid consequences of acute rejection in the elderly, observational studies support antibody induction with depletive antibodies, calcineurin-inhibitor, MMF and steroids; calcineurin-inhibitor-minimization is not recommended.

CONCLUSIONS

There is very limited evidence for the benefits and harms of different immunosuppression strategies in the elderly. Most of the published literature are observational studies, and randomized controlled trials are urgently needed.

Risk Stratification for Rejection and Infection after Kidney Transplantation

BACKGROUND AND OBJECTIVES

Definition of individual risk profile is the first step to implement strategies to keep the delicate balance between under- and overimmunosuppression after kidney transplantation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used data from the Efficacy Limiting Toxicity Elimination Symphony Study (1190 patients between 2002 and 2004) to model risk of rejection and infection in the first year after kidney transplantation. External validation was performed in a study population from the Fixed-Dose Concentration-Controlled Trial (630 patients between 2003 and 2006).

RESULTS

Despite different temporal dynamics, rejections and severe infections had similar overall incidences in the first year after transplantation (23.4% and 25.5%, respectively), and infections were the principal cause of death (43.2% of all deaths). Recipient older age, deceased donor, higher number of HLA mismatches, and high risk for cytomegalovirus disease were associated with infection; deceased donor, higher number of HLA mismatches, and immunosuppressive therapy including cyclosporin A (compared with tacrolimus), with rejection. These factors were integrated into a two-dimensional risk stratification model, which defined four risk groups: low risk for infection and rejection (30.8%), isolated risk for rejection (36.1%), isolated risk for infection (7.0%), and high risk for infection and rejection (26.1%). In internal validation, this model significantly discriminated the subgroups in terms of composite end point (low risk for infection/rejection, 24.4%; isolated risk for rejection and isolated risk for infection, 31.3%; high risk for infection/rejection, 54.4%; P<0.001), rejection episodes (isolated risk for infection and low risk for infection/rejection, 13.0%; isolated risk for rejection and high risk for infection/rejection, 24.2%; P=0.001), and infection episodes (low risk for infection/rejection and isolated risk for rejection, 12.0%; isolated risk for infection and high risk for infection/rejection, 37.6%; P<0.001). External validation confirmed the applicability of the model to an independent cohort.

CONCLUSIONS

We propose a two-dimensional risk stratification model able to disentangle the individual risk for rejection and infection in the first year after kidney transplantation. This concept can be applied to implement a personalized immunosuppressive and antimicrobial treatment approach.

Pharmacokinetics and pharmacodynamics of immunosuppressive drugs in elderly kidney transplant recipients

Elderly patients are a fast growing population among transplant recipients over the past decades. Both the innate and adaptive immune reactivity decrease with age, which is believed to contribute to the decreased incidence of acute rejection and increased infectious death rate in elderly transplant recipients. In contrast to recipient age, donor age is associated with a higher incidence of acute rejection. Pharmacokinetic studies in renal transplant recipients show that CNI troughs are >5% higher in elderly compared to younger patients given the same dose normalized by body weight. This may impact the starting dose of tacrolimus and cyclosporine. Possibly in elderly patients the intracellular (in lymphocyte) concentrations are relatively high in relation to the whole blood concentration, resulting in a stronger pharmacodynamic effect at the same whole blood trough concentration. For cyclosporine this has been shown, but it is not clear if the same is true for other immunosuppressive drugs. Pharmacodynamic studies have compared the inhibition of target enzymes, or more downstream effects of immunosuppressive drugs, in younger and older patients. Measurement of nuclear factor of activated T-cell (NFAT)-regulated gene expression (RGE), a pharmacodynamic read-out of CNI, is a promising biomarker of immunosuppression. Low levels of NFAT RGE are associated with increased risk of infection and non-melanoma skin cancer in elderly patients. Clinical trials to evaluate the safety and efficacy of immunosuppression regimens in this specific patient population, which is underrepresented in published trials, are lacking. More studies in elderly patients are needed to investigate the impact of age on the pharmacokinetics or pharmacodynamics of immunosuppressive drugs, and to decide on the optimal regimen and target levels for elderly transplant recipients.

Lower calcineurin inhibitor doses in older compared to younger kidney transplant recipients yield similar troughs

The number of older adults undergoing kidney transplantation has increased, yet little is known about calcineurin inhibitor (CNI) metabolism in this group. We studied CNI troughs and doses to determine if there were age-related differences in metabolism and dose requirements. We studied 348 young (18-34 years), 1831 middle (35-64 years) and 374 older (65-84 years) adult kidney transplant recipients enrolled in a seven-center prospective study. Troughs were obtained from each patient 2×/week in weeks 1-8 and 2×/month in months 3-6. A multivariable linear-mixed model examined the effect of age on log dose and weight normalized troughs. Older recipients had higher normalized tacrolimus troughs than middle or young age adults despite receiving doses a median of 1-2 mg/day lower. Age and CYP3A5*1 genotype had the largest effect on tacrolimus troughs. Older recipients also had higher normalized cyclosporine troughs than middle or young adults despite receiving median doses 100 mg/day lower. After normalization for dose and weight, CNI troughs were more than 50% higher in older adults than young adults. These data support age-related changes in CNI metabolism. Further studies are needed to determine optimal dosing of CNIs in the elderly.

Elderly recipients of hepatitis C positive renal allografts can quickly develop liver disease

Our institution explored using allografts from donors with Hepatitis C virus (HCV) for elderly renal transplantation (RT). Thirteen HCV- elderly recipients were transplanted with HCV+ allografts (eD+/R-) between January 2003 and April 2009. Ninety HCV- elderly recipients of HCV- allografts (eD-/R-), eight HCV+ recipients of HCV+ allografts (D+/R+) and thirteen HCV+ recipients of HCV- allografts (D-/R+) were also transplanted. Median follow-up was 1.5 (range 0.8-5) years. Seven eD+/R- developed a positive HCV viral load and six had elevated liver transaminases with evidence of hepatitis on biopsy. Overall, eD+/R- survival was 46% while the eD-/R- survival was 85% (P = 0.003). Seven eD+/R- died during follow-up. Causes included multi-organ failure and sepsis (n = 4), cancer (n = 1), failure-to-thrive (n = 1) and surgical complications (n = 1). One eD+/R- died from causes directly related to HCV infection. In conclusion, multiple eD+/R- quickly developed HCV-related liver disease and infections were a frequent cause of morbidity and mortality.

Rabbit antithymocyte induction and dosing in deceased donor renal transplant recipients over 60 yr of age

BACKGROUND

Antithymocyte globulin (rATG) is a commonly used induction agent in renal transplantation; however, data in older kidney recipients are limited.

METHODS

We reviewed charts of 301 deceased donor renal transplants who received a protocol consisting of 3-7 doses of rATG and triple maintenance therapy. Outcomes of patients >60 yr of age (n = 45) were compared to those aged 18-59 yr (n = 256).

RESULTS

  Older recipients had more diabetics, were more likely to receive expanded criteria donor kidneys (p < 0.01), and over 30% were sensitized. Recipients >60 received less cumulative rATG (4.6 vs. 5.1 mg/kg; p < 0.01). Three-yr acute rejection was lower in the >60 group (2% vs. 16%, p < 0.01) although glomerular filtration rates were similar between groups. Actuarial graft survival was similar; however, patient survival in the >60 group at three yr was lower (80% vs. 95%; p = 0.02). Specifically, patients >60 with delayed graft function and rATG cumulative dosing >6 mg/kg had a survival of <50% by two yr.

CONCLUSION

Recipients over 60 yr receiving rATG induction have acceptable renal function and a low risk of rejection; however, reduced survival was noted among those receiving >6 mg/kg. These data suggest that when used, lower cumulative dosages of rATG are preferable in the older recipient.

Renal transplantation in the elderly

Elderly patients are increasingly being considered for kidney transplantation due to a global explosion of the aging population with end-stage renal disease (ESRD). However, mounting scarcity of available organs for transplant has led to a wider disparity between organ supply and demand. Consequently, the criteria for accepting kidneys for transplantation have been extended in an attempt to allow the use of organs from elderly donors or those with significant co-morbidities, so-called "expanded criteria donor" (ECD) kidneys. Excellent outcomes have been achieved from ECD kidneys with appropriate donor and recipient profiling and selection. With increasing recovery efforts directed at older donors, the concept of age-matching is becoming more accepted as a method of optimizing utilization of organs in elderly donors and recipients. Utilization of pulsatile perfusion has further improved ECD outcomes and helped the decision-making process for the UNOS (United Network for Organ Sharing) offer. However, age-related immune dysfunction and associated co-morbidities make the elderly transplant recipients ever more susceptible to complications associated with immunosuppressive agents. Consequently, the elderly population is at a higher risk to develop infections and malignancy in the post-transplant period notwithstanding improved transplant outcomes. Appropriate immunosuppressive agents and dosages should be selected to minimize adverse events while reducing the risk of acute rejections and maximizing patient and renal allograft survival.

Ectopic testicular xenografts from newborn hamsters (Phodopus sungorus) show better spermatogenic activity in aged compared with young recipients

The mechanisms behind testicular aging are poorly understood. Previous studies suggest that the testicular microenvironment is more affected by age than the male germ cell lineage. Here we analyze male reproductive aging using a unique xenografting approach. By exposing young and aged mice to newborn hamster testicular tissue, we can explore (a) whether the development and endocrine activity of hamster testicular grafts and the initiation of stem cell activity within them are affected by age of the recipients and (b) whether the endocrine response to the xenografted hamster tissue varies with recipient age. Newborn Djungarian hamster (Phodopus sungorus) testes were grafted into young (12 weeks) and aged (1 year) adult castrated nude mice. We also analyzed intact and castrated young and old control groups. After 13 weeks, 100 grafts were recovered from a total of 15 recipients and were histologically analyzed. Anatomical and endocrine parameters were recorded for each recipient as well as for the controls. Xenografted recipients responded with a normalization of their endocrine and anatomical parameters to an extent typical for their age. Although recipient age did not significantly affect graft survival and size, histopathological changes as well as spermatogenic damage within the grafts were more pronounced in the young recipients (56% Sertoli-cell-only tubules vs. 32% in the old recipients). We conclude from our data that the androgen-related changes associated with male reproductive aging are not primarily controlled by the testis. We speculate that the better development of testicular grafts in aged recipients may be owing to immunosenescence.

Renal transplantation outcomes: a comparative analysis between elderly and younger recipients

Renal transplantation is presently the best treatment for end-stage renal disease, although considered contraindicated for elderly patients. However, more investigation is needed due to higher life expectancy rates of the general population and the increasing number of over 60-yr-old patients with chronic renal failure dependent upon dialysis. This study aims to determine graft and patient survival rates of renal transplant patients 60 yr and older compared to a younger group (50-59 yr old). Relevant pre- and post-transplant clinical data related to graft and patient survival in both groups were also investigated. Three-hundred and twenty consecutive renal transplant patients were enrolled in this study and grouped based on age at the time of the transplantation: one-hundred and ten patients at or over 60 yr old (elderly group) and 210 patients ranging from 50 to 59 yr old (younger group). There were no statistical differences in either group regarding clinical characteristics and immunological risk factors. The incidence of acute rejection was higher in the younger group (37.6%) than in the elderly (22.7%) (p = 0.01). Censored to death graft survivals at five yr were respectively 86.7% for patients > or = 60 yr and 82.1% for patients 50-59 yr old (p = 0.49). Patient survival rates at five yr were respectively 76.2% for patients > or = 60 yr and 81.6% for patients 50-59 yr old (p = 0.33). Our data show that renal transplantation for elderly patients has similar results to those found in younger individuals, which does not make age, in and of itself, a contraindication for transplantation.

Immunosuppression of the elderly kidney transplant recipient

The growing number of elderly patients with end-stage kidney disease awaiting transplantation has resulted in a corresponding rise in the number of elderly transplant recipients. In this paper, we review existing literature on age-related changes, transplant outcomes, and complications in the elderly in an attempt to propose a tailored approach to immunosuppression management in this group of patients. Despite the fact that the benefit of transplantation in the elderly is well established, clinical trials evaluating the safety and efficacy of immunosuppression regimens are lacking. Until such data exists, immunosuppression of the elderly transplant recipient should be based on the traditional principles which guide all transplant protocols and consideration of factors that are unique to the elderly. There are limited data regarding age-related changes in immune function and metabolism of immunosuppression agents in this population. Results of registry data analyses suggest that the risk of acute rejection decreases with age; however, the impact of acute rejection on long-term allograft function is greater in this population. There is also an increased risk of infection and adverse events posttransplantation among these patients. Elderly patients are more likely to receive organs from extended criteria donors and the impact of donor factors on transplant outcomes must therefore be considered. Taking these factors into consideration, we propose an approach to immunosuppression in the elderly based on individual risk stratification of treatment failure and the potential for adverse events.

Younger age and antibody induction increase the risk for infection in pediatric renal transplantation: a NAPRTCS report

Infections now exceed rejection as a cause of hospitalization in the first 2 years post-renal transplantation. We analyzed data from the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) to determine risks for hospitalization for infection (HI), either bacterial (HBI) or viral (HVI). 3106 children transplanted between 1996 and 2002 with 2-year follow-up were analyzed. Univariate and multivariate logistic regression analyses identified factors for cause-specific hospitalization.

RESULTS

23.4% experienced HBI, 23.9% HVI; 8.9% were hospitalized for both. Children 0-1 years age at transplant had higher rates of HI (64.2%), HBI (40.3%) and HVI (43.3%) compared to >12 years (31%, 17.5% and 18.9%, p < 0.0001). In comparison to no induction, patients receiving monoclonal or polyclonal antibody were more likely to have HI (>42% vs. 34.0%), HBI (>24% vs. 21%) or HVI (>29% vs. 21%, all p < 0.003) but had equivalent graft survival (p = NS). Higher rates of HI, HBI and HVI were also seen with prophylactic antimicrobial use and with >5 transfusions pretransplant. Since antibody induction in recent era was not associated with better graft or patient survival but was associated with more HI and HVI, the need for routine antibody induction in children needs to be reassessed.

Transplantation rénale du sujet âgé

For ten years, an increase in the number of elderly patients on renal transplant waiting lists has occured. In an attempt to close the widening gap between supply and demand and because the demand for kidneys for younger patients already surpasses the supply, transplant physicians nowadays accept organs from older donors that might have been deemed inappropriate in the past. Programs of age matching between donors and recipients and of dual-kidneys transplantation have emerged. The initial results of these programs are encouraging with excellent patient and graft survival at one and three years.

Preferential allocation of marginal kidney allografts to elderly recipients combined with modified immunosuppression gives good results

BACKGROUND

There is an increasing tendency to allocate kidneys from marginal donors in older recipients. This combination optimizes the uses of an expanded donor pool but demands attention for the higher nephrotoxic sensitivity of the kidney and the increased immunosuppression vulnerability of the elderly recipients. We aimed to reduce these hazards by means of a calcineurin-free induction therapy followed by a maintenance regimen targeted to minimize/withdraw steroid.

METHODS

Eighty-eight single (43%) or double (57%) transplant recipients (58.4+/-5.7 years) from 88 marginal donors (67+/-8.3 years) received monoclonal anti-IL-2 receptor antibodies, mycophenolate mofetil (MMF), and steroid. When serum creatinine was less than 2.6 mg/dL, tacrolimus was started and MMF was withdrawn when the tacrolimus trough level was above 15 ng/ml. Steroid was tapered to 5 mg at day 45 and then progressively reduced.

RESULTS

Overall patient and graft survival at the first and fourth year were respectively 100 and 96%, and 98 and 79%. Acute rejection rate was 13.6% (12/88), creatinine clearance remained stable (48.2 ml/min at the sixth month, 50.9 ml/min at 48th month). At the first, second, third, and fourth years, 23, 69, 80, and 100% of recipients were off steroids. For those on steroids, mean dose was respectively 2.6 mg/day from month 12. No recipient re-assumed steroids

CONCLUSIONS

In the "old-for-old" allocation, the calcineurin-inhibitor avoidance at induction and the steroid withdrawal/minimization during the tacrolimus-based maintenance regimen allow a low acute rejection rate, a stable renal function, and favorable recipient and graft outcomes.

Influence of age in renal transplant infections: cases and controls study

Kidney transplantation in elderly patients is a good therapeutic option, but the incidence of infections compared to younger patients must be studied. Case and control study was performed with 40 cases (patients older than 65) and 40 controls (younger than 65) receiving a kidney transplant between January 2000 and August 2002. In 32 cases (80%) and in 14 controls (32%), some type of infection appeared during the follow-up (odds ratio [OR] 5; 95% CI 1.6-20). The percentage of patients with bacterial infections was higher in the cases (70% vs. 28%; OR 5.7; 95% CI 1.9-20), especially for urinary infections. No differences for viral and fungal infections were observed in the two groups. Mortality rate was 13% in the cases (5% due to infections), whereas there was no controls' mortality. Although the number of bacterial infections was higher, kidney transplantation in elderly patients is a secure procedure.

Tacrolimus/mycophenolate mofetil-based immunosuppression in aged kidney transplant. A prospective study

BACKGROUND

At the moment, controversy has arisen about immunosuppression in aged kidney transplant recipients. We present our results on the efficacy and safety of induction treatment based on tacrolimus (FK506) and mycophenolate mofetil (MMF).

MATERIAL AND METHOD

We performed 72 transplants in patients of 60 years or older. Induction treatment consisted on (FK 506) 0.1 mg/kg/day and MMF 2 gr/day. Antilymphocyte serum was administered with delayed graft function. A total of 54 patients received kidneys from donors over 60 years old.

RESULTS

Cold ischemia time was 16.4 h (S=5.7). Delayed graft function occurred in 35 patients (48.6%). Acute rejection was observed in nine patients (12.5%). Opportunistic infections were found in 19 patients (26.4%). Seven patients died due to sudden death (1), acute myocardial infarction (1), stroke (1), infection (3), and neoplasm (1). At 1, 2, and 3 years, serum creatinine was 145, 163, and 156 mmol/l; patient survival 93%, 90%, and 90%; graft survival 93%, 90%, and 87%; and death-censored graft survival 100%, 100%, and 97%, respectively.

CONCLUSION

These immunosuppressive guidelines appear to be efficacious and safe in kidney transplant in elderly recipients.

Pharmacokinetic Considerations Relating to Tacrolimus Dosing in the Elderly

Relaxation of the upper age limits for solid organ transplantation coupled with improvements in post-transplant survival have resulted in greater numbers of elderly patients receiving immunosuppressant drugs such as tacrolimus. Tacrolimus is a potent agent with a narrow therapeutic window and large inter- and intraindividual pharmacokinetic variability. Numerous physiological changes occur with aging that could potentially affect the pharmacokinetics of tacrolimus and, hence, patient dosage requirements. Tacrolimus is primarily metabolised by cytochrome P450 (CYP) 3A enzymes in the gut wall and liver. It is also a substrate for P-glycoprotein, which counter-transports diffused tacrolimus out of intestinal cells and back into the gut lumen. Age-associated alterations in CYP 3A and P-glycoprotein expression and/or activity, along with liver mass and body composition changes, would be expected to affect the pharmacokinetics of tacrolimus in the elderly. However, interindividual variation in these processes may mask any changes caused by aging. More investigation is needed into the impact aging has on CYP and P-glycoprotein activity and expression. No single-dose, intense blood-sampling study has specifically compared the pharmacokinetics of tacrolimus across different patient age groups. However, five population pharmacokinetic studies, one in kidney, one in bone marrow and three in liver transplant recipients, have investigated age as a co-variate. None found a significant influence for age on tacrolimus bioavailability, volume of distribution or clearance. The number of elderly patients included in each study, however, was not documented and may have been only small. It is likely that inter- and intraindividual pharmacokinetic variability associated with tacrolimus increase in elderly populations. In addition to pharmacokinetic differences, donor organ viability, multiple co-morbidity, polypharmacy and immunological changes need to be considered when using tacrolimus in the elderly. Aging is associated with decreased immunoresponsiveness, a slower body repair process and increased drug adverse effects. Elderly liver and kidney transplant recipients are more likely to develop new-onset diabetes mellitus than younger patients. Elderly transplant recipients exhibit higher mortality from infectious and cardiovascular causes than younger patients but may be less likely to develop acute rejection. Elderly kidney recipients have a higher potential for chronic allograft nephropathy, and a single rejection episode can be more devastating. There is a paucity of information on optimal tacrolimus dosage and target trough concentration in the elderly. The therapeutic window for tacrolimus concentrations may be narrower. Further integrated pharmacokinetic-pharmacodynamic studies of tacrolimus are required. It would appear reasonable, based on current knowledge, to commence tacrolimus at similar doses as those used in younger patients. Maintenance dose requirements over the longer term may be lower in the elderly, but the increased variability in kinetics and the variety of factors that impact on dosage suggest that patient care needs to be based around more frequent monitoring in this age group.

Hepatitis C and renal transplantation in the era of modern immunosuppression

Kidneys from donors who are positive for hepatitis C virus (DHCV+) have recently been identified as an independent risk factor for mortality after renal transplantation. However, it has not been determined whether risk persists after adjustment for baseline cardiac comorbidity or applies in the era of modern immunosuppression. Therefore, a historical cohort study was conducted of US adult cadaveric renal transplant recipients from January 1, 1996, to May 31, 2001; followed until October 31, 2001. A total of 36,956 patients had valid donor and recipient HCV serology. Cox regression analysis was used to model adjusted hazard ratios for mortality and graft loss, respectively, adjusted for other factors, including comorbid conditions from Center for Medicare and Medicaid Studies Form 2728 and previous dialysis access-related complications. It was found that DHCV+ was independently associated with an increased risk of mortality (adjusted hazard ratio, 2.12, 95% confidence interval, 1.72 to 2.87; P < 0.001), primarily as a result of infection. Mycophenolate mofetil was associated with improved survival in DHCV+ patients, primarily related to fewer infectious deaths. Adjusted analyses limited to recipients who were HCV+, HCV negative, or age 65 and over, or by use of mycophenolate mofetil confirmed that DHCV+ was independently associated with mortality in each subgroup. It is concluded that DHCV+ is independently associated with an increased risk of mortality after renal transplantation adjusted for baseline comorbid conditions in all subgroups. Recipients of DHCV+ organs should be considered at high risk for excessive immunosuppression.

Drug Therapy in Transplant Recipients

Elderly patients with end-stage organ failure are now more frequently undergoing transplantation. Medication management in this population is challenging because of the combination of multiple comorbidities, polypharmacy, and immunological, pharmacokinetic and pharmacodynamic changes attributable to the aging process. Immunosuppressive medications can exacerbate pre-existing medical conditions and promote the development of disease processes. Cardiovascular disorders, such as hypertension, coronary artery disease, congestive heart failure and arrhythmias are common in elderly transplant recipients, and account for most of the deaths in this population. Blood pressure, blood glucose and cholesterol control is of particular concern because elderly transplant recipients frequently have or develop these complications. Elderly transplant recipients are commonly receiving anticoagulation therapy with warfarin and are at a higher risk of bleeding, especially if they have renal dysfunction. Infectious complications occur frequently in the transplanted population, with pneumonia being the most common infection seen in hospitalised patients. Attention to vaccination for the prevention of influenza and pneumococcal infections is important because of the increased risk of these diseases in this population. Depression itself has been associated with decreased survival in older individuals, and depression in elderly transplant recipients may be reversible with the administration of pharmacological agents. Effective long-term care of transplant recipients demands an understanding of how particular medications affect clinical evaluation and treatment. This article addresses some of the practical issues surrounding medication management and prevention of these particular problems in elderly transplant recipients.