Infectious complications in geriatric renal transplant patients: comparison of two immunosuppressive protocols

[Vacuum sealing of extensive wound healing disorders after kidney transplantation]

With the introduction of mycophenolate mofetil (MMF) in renal transplantation, acute rejection episodes diminished and short-term graft survival improved. Better graft outcome, however, is followed by several surgical complications attributed to MMF. Patients with risk factors (adiposity, diabetes mellitus, advanced age) show an increased rate of healing by second intention. We treated two patients with the vacuum sealing technique so that after 15 days a secondary suture became possible in each case. To date the vacuum sealing technique has been used mainly in traumatology, abdominal surgery, surgery for acute infections of soft tissue and bone, and problem wounds with reduced wound-healing capacity (chronic leg ulcer). This article presents two cases of successful application of the vacuum sealing technique in renal transplantation after prolonged wound healing.

Dialysis, kidney transplantation, or pancreas transplantation for patients with diabetes mellitus and renal failure: a decision analysis of treatment options

Patients with type 1 diabetes mellitus and end-stage renal disease may remain on dialysis or undergo cadaveric kidney transplantation, living kidney transplantation, sequential pancreas after living kidney transplantation, or simultaneous pancreas-kidney transplantation. It is unclear which of these options is most effective. The objective of this study was to determine the optimal treatment strategy for type 1 diabetic patients with renal failure using a decision analytic Markov model. Input data were obtained from the published medical literature, the United Network for Organ Sharing registry, and patient interviews. The outcome measures were life expectancy (in life-years [LY]) and quality-adjusted life expectancy (in quality-adjusted life-years [QALY]). Living kidney transplantation was associated with 18.30 LY and 10.29 QALY; pancreas after kidney transplantation, 17.21 LY and 10.00 QALY; simultaneous pancreas-kidney transplantation, 15.74 LY and 9.09 QALY; cadaveric kidney transplantation, 11.44 LY and 6.53 QALY; dialysis, 7.82 LY and 4.52 QALY. The results were sensitive to the value of several key variables. Simultaneous pancreas-kidney transplantation had the greatest life expectancy and quality-adjusted life expectancy when living kidney transplantation was excluded from the analysis. These data indicate that living kidney transplantation is associated with the greatest life expectancy and quality-adjusted life expectancy for type 1 diabetic patients with renal failure. Treatment strategies involving pancreas transplantation should be considered for patients with frequent metabolic complications of diabetes and for those patients who favor kidney-pancreas transplantation over kidney transplantation alone. For patients without a living donor, simultaneous pancreas-kidney transplantation is associated with the greatest life expectancy.

Kidney transplantation in the elderly: a decision analysis

Transplantation offers superior life expectancy and quality of life compared with dialysis in young patients with end-stage renal failure. However, the initial risks of mortality and morbidity are high. This study used a decision analysis model to evaluate the costs and benefits of kidney transplantation versus continued dialysis for older patients with renal failure. A decision analytic model comparing cadaveric renal transplantation to continued hemodialysis treatment was developed. The base case considered a theoretical cohort of patients aged 65 yr without known comorbidity or contraindications to transplantation who would have to wait 2 yr for a cadaveric transplant. Separate models were constructed for patients with diabetes or cardiovascular disease and for patients receiving an organ after a variety of wait-list times. Probability, utility, and survival data were obtained from published reports and renal registries. For 65-yr-old patients, quality-adjusted life expectancy increased by 1.1 quality-adjusted life years (QALY) at an incremental cost of $67,778 per QALY. Assuming a 2-yr wait-listed time, transplantation remained economically attractive for 70-yr-old patients (incremental cost effectiveness [ICE], $79,359 per QALY) but was less economically attractive for those over 75 yr of age (ICE, $99,553) or for 70-yr-olds with either cardiovascular disease or diabetes (ICE, $126,751 and $161,090 per QALY, respectively). The analytic results were sensitive only to the time spent waiting for the graft. The cost-effectiveness reduced such that the costs associated with one QALY were in excess of $100,000/yr when the probability of a complication was > or = 50% per 3-mo cycle and when the utility of transplantation fell below 0.62. If available within a timely period, transplantation may offer substantial clinical benefits to older patients at a reasonable financial cost. Prolonged waiting times dramatically decrease the clinical benefits and economic attractiveness of transplantation, suggesting that living donor transplantation may be of particular benefit in this population.

Rejection and recipient age

In transplantation the risk of acute rejection decreases with recipient age. This is clearly illustrated in transplantation of a non-vascularised tissue, such as the cornea. In vascularised transplants, such as kidneys, acute rejection decreases with recipient age, but the phenomenon is obscured by the fact that chronic allograft nephropathy increases with age, and is further confounded by increased death from infectious disease and drug-related causes. The underlying cellular mechanisms responsible for this weakening of rejection are discussed, as is defective signal transduction leading to decreased activation of cells and decreased resistance to immunosuppressive drugs. This supports a view that less intensive immunosuppressive drug therapy is desirable in elderly recipients. Although pharmacokinetic studies are documented, there are no routine assays to measure efficacy of these drugs in individual patients. In summary, the decline in acute rejection with increasing recipient age may be due both to immunosenescence and decreased resistance to immunosuppressive drugs. Future assays to test these mechanisms could be used to tailor therapy to individual needs.

Kidney transplantation in older patients: benefits and risks

The proportion of older patients accepted for dialysis is increasing every year both in the US and abroad. Of the two treatment modalities for end-stage renal disease, i.e. dialysis and transplantation, the latter offers more freedom and is associated with better clinical outcome. Most elderly patients seem to have excellent functional rehabilitation after a kidney transplant. However, in view of the wide gap between the availability of cadaver organs and the people in need, giving the precious organ to the elderly who have a shorter expected lifespan may present an ethical problem. Therefore, it has become increasingly important to offer the kidney to only those who have no significant comorbid conditions or other high risk factors, so as to improve the odds of success after renal transplantation.

Is mycophenolate mofetil less safe than azathioprine in elderly renal transplant recipients?

BACKGROUND

Mycophenolate mofetil (MMF) is a potent immunosuppressive agent that has been shown to be superior to azathioprine in preventing early acute rejection in the general renal transplant population. However, it is uncertain whether these benefits also apply to older renal transplant recipients, who are known to be more susceptible to infectious complications and have considerably lower rates of rejection and immunological graft loss.

METHODS

A retrospective analysis was undertaken of all elderly (> or =55 years old) renal transplant recipients who underwent renal transplantation at the Princess Alexandra Hospital (1994-2000) and received either MMF (n=60) or azathioprine (n=55) in combination with prednisolone and cyclosporin. Data were analyzed on an intention-to-treat basis using a multivariate Cox proportional hazards model.

RESULTS

The azathioprine- and MMF-treated groups were well matched at baseline with respect to demographic characteristics, end-stage renal failure causes and transplant characteristics. Compared with the MMF cohort, azathioprine-treated patients experienced a shorter time to first rejection [hazard ratio (HR) 4.47, 95% CI 1.53-13.1, P<0.01]. However, azathioprine-treated patients were also less likely to develop opportunistic infections (HR 0.11, 95% CI 0.03-0.41, P=0.001). No differences were observed between the two groups with respect to hospitalization rates, intensive care admissions, hematological complications, or posttransplant malignancies. Actuarial 2-year survival rates for the azathioprine- and MMF-treated patients were 100 and 87%, respectively (P<0.001). The principal cause of death in the MMF cohort was infection. Using a multivariate Cox regression analysis of patient survival, an adjusted hazard ratio of 0.01 (95% CI 0.001-0.08, P=0.001) was calculated in favor of azathioprine. Overall graft survival also tended to be better in patients receiving azathioprine (HR 0.27, 95% CI 0.06-1.33, P=0.11),

CONCLUSIONS

In elderly renal transplant recipients, the combination of MMF, cyclosporin, and prednisolone appears to result in a worse outcome compared with the less potent combination of azathioprine, cyclosporin, and prednisolone. Future prospective studies need to specifically evaluate the risk/benefit ratios of newer, more potent immunosuppressive protocols, such as MMF-based regimens, in this important and sizeable patient subgroup.

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

Renal transplantation is an accepted and successful treatment modality in elderly patients with end-stage renal disease. In comparison with maintenance dialysis, transplantation has been shown to confer a mortality benefit as well as improvements in quality of life in older individuals with end-stage renal disease. Despite this, overall outcomes of renal transplantation in elderly individuals have, in general, been less successful than those of younger renal transplant recipients. Largely, this has been due to the particular vulnerability of elderly patients to the immunosuppressive medications used in renal transplantation. This review article covers these issues in some detail and briefly discusses some of the pharmacokinetic, pharmacodynamic, physiological and immunological differences between younger and older transplant recipients. Elderly renal transplant recipients have both a higher rate of patient death and allograft loss censored for death. Upon multivariate analysis, age of the recipient is strongly associated with allograft loss independent of other known factors. Acute rejections are less frequent in older individuals; however the consequence of a rejection if it occurs is negative for long-term graft survival. On the other hand, death by infection is vastly increased in older versus younger renal transplant recipients. In general, the pharmacokinetics of the immunosuppressive agents are little affected by age, but the tolerance to these agents seems to decrease with increasing age. Elderly renal transplant recipients present a very difficult clinical challenge. As the elderly become an ever-increasing segment of the renal transplant population, new and innovative immunosuppressive strategies will have to be considered and applied.

Are wound complications after a kidney transplant more common with modern immunosuppression?

BACKGROUND

The most common surgical complication after a kidney transplant is likely related to the wound. The purpose of this analysis was to determine the incidence of, and risk factors for, wound complications (e.g., infections, hernias) in kidney recipients and to assess whether newer immunosuppressive drugs increase the risk for such complications.

METHODS

Between January 1, 1984 and September 30, 1998, we performed 2013 adult kidney transplants. Of these 2013 recipients, 97 (4.8%) developed either a superficial or a deep wound infection. Additionally, 73 (3.6%) recipients developed either a fascial dehiscence or a hernia of the wound. We used univariate and multivariate techniques to determine significant risk factors and outcomes.

RESULTS

Mean time to development of a superficial infection (defined as located above the fascia) was 11.9 days posttransplant; to development of a deep infection (defined as located below the fascia), 39.2 days; and to development of a hernia or fascial dehiscence, 12.8 months. By multivariate analysis, the most significant risk factor for a superficial or deep wound infection was obesity (defined as body mass index>30 kg/m2) (RR=4.4, P=0.0001). Other significant risk factors were a urine leak posttransplant, any reoperation through the transplant incision, diabetes, and the use of mycophenolate mofetil (MMF) (vs. azathioprine) for maintenance immunosuppression (RR=2.43, P=0.0001). Significant risk factors for a hernia or fascial dehiscence were any reoperation through the transplant incision, increased recipient age, obesity, and the use of MMF (vs. azathioprine) for maintenance immunosuppression (RR=3.54, P=0.0004). Use of antibody induction and treatment for acute rejection were not significant risk factors for either infections or hernias. Death-censored graft survival was lower in recipients who developed a wound infection (vs. those who did not); it was not lower in recipients who developed an incisional hernia or facial dehiscence (vs. those who did not).

CONCLUSIONS

Despite immunosuppression including chronic steroids, the incidence of wound infections, incisional hernias, and fascial dehiscence is low in kidney recipients. As with other types of surgery, the main risk factors for postoperative complications are obesity, reoperation, and increased age. However, in kidney recipients, use of MMF (vs. azathioprine) is an additional risk factor -one that potentially could be altered, especially in high-risk recipients.

Polyoma viral infection in renal transplantation: the role of immunosuppressive therapy

BACKGROUND

Polyoma virus infection in renal transplant recipients has been observed with increasing frequency in recent years. Renal allograft involvement in this condition may occur as a result of primary infection or secondary to reactivation of the latent virus. Interstitial nephritis, ureteric stenosis, rise in serum creatinine and allograft function loss have been attributed to this viral infection.

METHODS

In this study we reviewed our experience with 8 patients who developed polyoma viral infection confirmed by allograft biopsy. All patients were receiving mycophenolate mofetil as part of the immunosuppression and 7 of the 8 patients were on tacrolimus. All patients have biopsy proven polyoma viral infection. The following therapeutic maneuvers were carried out following the diagnosis of polyoma viral infection: 1) stopping mycophenolate and 2) switching tacrolimus to cyclosporine or reducing the tacrolimus dose to adjust it at a lower therapeutic trough level. The clinical course and outcome of our patients were reviewed in relation to manipulation of immunosuppressive medications.

RESULTS

The incidence of this infection in our transplant program in the last 3 yr was 5.3%. Seventy-five percent of the patients had at least one rejection episode and 63% had more than one rejection episode. The main risk factor for the development of polyoma viral infection was related to the intensity of immunosuppression. The use of antirejection therapy after histological diagnosis of polyoma virus infection was not associated with improvement of renal function despite the histological appearance of acute rejection. Thus, the interstitial nephritis associated with polyoma viral infection appears to be an inflammatory response to the virus rather than acute rejection. Six out of the 8 patients stabilized renal function with reduction in immunosuppression.

CONCLUSIONS

Reduction in immunosuppression was associated with the stabilization of renal function when instituted early. However, these patients were left with a degree of allograft dysfunction and their outcome may be significantly compromised. The lack of effective antiviral therapy for polyoma virus may limit the use of newer and more potent immunosuppressive medications.

Exponentially increased risk of infectious death in older renal transplant recipients

BACKGROUND

The benefit of renal transplantation for patients with end-stage renal disease (ESRD) has been well documented. This benefit is seen throughout all age ranges of patients. However, it has been documented that older renal transplant recipients are at increased risk for death because of infectious causes when compared with younger recipients. The present study addresses whether this increased risk merely parallels an age-related increase in infectious mortality or is reflective of a particular vulnerability in older renal transplant recipients.

METHODS

Patients wait-listed and transplanted between 1988 and 1997 were analyzed utilizing the United States Renal Data System (USRDS) database. The primary study end point was patient death secondary to infection. Secondary end points included death secondary to cardiovascular cause and malignancy. Cox-proportional hazard models were utilized with all pertinent variables.

RESULTS

Death related to infectious cause increased exponentially in transplanted patients with increasing age (slope = 2.90.34x), while it increased linearly (slope = 1.9x + 8.6) with increasing age for those patients on the waiting list. Overall mortality increases with age were equal between the wait-listed and transplanted groups.

CONCLUSIONS

The overall survival benefit of transplantation is maintained in the older age groups. However, renal transplantation is associated with an increased risk for infectious death beyond the expected age-related increased risk in patients on the renal transplant waiting list. This may have an impact on future immunosuppressive regimens in this population.

New developments in the management of cytomegalovirus infection and disease after renal transplantation

The clinical management of cytomegalovirus infection and disease in renal transplant recipients has recently been significantly improved with the availability of data on prophylaxis with oral ganciclovir and valacyclovir. In addition, significant progress in early diagnosis and the quantitation of viral load has been achieved. The influence of novel immunosuppressants on the clinical course of cytomegalovirus infection has been clarified to some extent by recent clinical data. The identification of risk factors for cytomegalovirus disease beyond seroconstellation and immunosuppression is an ongoing process that might lead to a more targeted use of antiviral agents, given the risk of ganciclovir resistance. The understanding of the effects of cytomegalovirus on long-term graft outcome still needs to be deepened in order to design cytomegalovirus-specific interventions to improve graft survival.

Renal transplantation in the elderly

As the number of elderly patients suffering from end-stage renal disease has increased almost threefold during the past 20 years all over the world, new strategies for the treatment of such patients have been developed. Better screening has made renal transplantation a valuable resource in elderly end-stage renal disease patients. Improved immunosuppressive protocols as well as the expansion of the donor pool by using older and living donors for older recipients have improved patient survival rates as well as the quality of life in this patient population.

African-American renal transplant recipients experience decreased risk of death due to infection: possible implications for immunosuppressive strategies

INTRODUCTION

African-American renal transplant recipients tend to experience more acute rejection episodes and have shorter graft survival than Caucasian renal transplant recipients. Various factors have been posited to be responsible for this difference, including relative under immunosuppression. We reasoned that by looking at the balance of acute rejections versus death due to infection, we could ascertain whether African-American renal recipients might have more reserve to tolerate an increase in pharmacological immunosuppression.

METHODS

We analyzed the United States Renal Data System (USRDS) data from 1987 to 1997 regarding acute rejection episodes and infectious deaths. All other pertinent factors were gathered for a multivariate analysis. A total number of 68,885 adult renal transplant recipients were analyzed.

RESULTS

When corrected for all covariates, the relative risk for acute rejection (1.3) was higher although the relative risk for infectious death was lower (0.7) in African-Americans as compared with Caucasians (P<0.01).

CONCLUSION

Our study would indicate that relative to Caucasians, African-American renal transplant recipients are at decreased risk for infectious death and therefore may tolerate the more intensive immunosuppression that may be necessary to narrow the gap in acute rejection rates between African-Americans and Caucasian renal transplant recipients.