Health System-Level Barriers to Living Donor Kidney Transplantation: Protocol for a Comparative Case Study Analysis

BACKGROUND

Living donor kidney transplantation (LDKT) is the best treatment option for patients with kidney failure and offers significant medical and economic advantages for both patients and health systems. Despite this, rates of LDKT in Canada have stagnated and vary significantly across Canadian provinces, the reasons for which are not well understood. Our prior work has suggested that system-level factors may be contributing to these differences. Identifying these factors can help inform system-level interventions to increase LDKT.

OBJECTIVE

Our objective is to generate a systemic interpretation of LDKT delivery across provincial health systems with variable performance. We aim to identify the attributes and processes that facilitate the delivery of LDKT to patients, and those that create barriers and compare these across systems with variable performance. These objectives are contextualized within our broader goal of increasing rates of LDKT in Canada, particularly in lower-performing provinces.

METHODS

This research takes the form of a qualitative comparative case study analysis of 3 provincial health systems in Canada that have high, moderate, and low rates of LDKT performance (the percentage of LDKT to all kidney transplantations performed). Our approach is underpinned by an understanding of health systems as complex adaptive systems that are multilevel and interconnected, and involve nonlinear interactions between people and organizations, operating within a loosely bounded network. Data collection will comprise semistructured interviews, document reviews, and focus groups. Individual case studies will be conducted and analyzed using inductive thematic analysis. Following this, our comparative analysis will operationalize resource-based theory to compare case study data and generate explanations for our research question.

RESULTS

This project was funded from 2020 to 2023. Individual case studies were carried out between November 2020 and August 2022. The comparative case analysis will begin in December 2022 and is expected to conclude in April 2023. Submission of the publication is projected for June 2023.

CONCLUSIONS

By investigating health systems as complex adaptive systems and making comparisons across provinces, this study will identify how health systems can improve the delivery of LDKT to patients with kidney failure. Our resource-based theory framework will provide a granular analysis of the attributes and processes that facilitate or create barriers to LDKT delivery across multiple organizations and levels of practice. Our findings will have practice and policy implications and help inform transferrable competencies and system-level interventions conducive to increasing LDKT.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/44172.

Health System–Level Barriers to Living Donor Kidney Transplantation: Protocol for a Comparative Case Study Analysis (Preprint).. [DOI: 10.2196/preprints.44172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

BACKGROUND

Living donor kidney transplantation (LDKT) is the best treatment option for patients with kidney failure and offers significant medical and economic advantages for both patients and health systems. Despite this, rates of LDKT in Canada have stagnated and vary significantly across Canadian provinces, the reasons for which are not well understood. Our prior work has suggested that system-level factors may be contributing to these differences. Identifying these factors can help inform system-level interventions to increase LDKT.

OBJECTIVE

Our objective is to generate a systemic interpretation of LDKT delivery across provincial health systems with variable performance. We aim to identify the attributes and processes that facilitate the delivery of LDKT to patients, and those that create barriers and compare these across systems with variable performance. These objectives are contextualized within our broader goal of increasing rates of LDKT in Canada, particularly in lower-performing provinces.

METHODS

This research takes the form of a qualitative comparative case study analysis of 3 provincial health systems in Canada that have high, moderate, and low rates of LDKT performance (the percentage of LDKT to all kidney transplantations performed). Our approach is underpinned by an understanding of health systems as complex adaptive systems that are multilevel and interconnected, and involve nonlinear interactions between people and organizations, operating within a loosely bounded network. Data collection will comprise semistructured interviews, document reviews, and focus groups. Individual case studies will be conducted and analyzed using inductive thematic analysis. Following this, our comparative analysis will operationalize resource-based theory to compare case study data and generate explanations for our research question.

RESULTS

This project was funded from 2020 to 2023. Individual case studies were carried out between November 2020 and August 2022. The comparative case analysis will begin in December 2022 and is expected to conclude in April 2023. Submission of the publication is projected for June 2023.

CONCLUSIONS

By investigating health systems as complex adaptive systems and making comparisons across provinces, this study will identify how health systems can improve the delivery of LDKT to patients with kidney failure. Our resource-based theory framework will provide a granular analysis of the attributes and processes that facilitate or create barriers to LDKT delivery across multiple organizations and levels of practice. Our findings will have practice and policy implications and help inform transferrable competencies and system-level interventions conducive to increasing LDKT.

INTERNATIONAL REGISTERED REPORT

DERR1-10.2196/44172

Health system barriers and facilitators to living donor kidney transplantation: a qualitative case study in British Columbia

BACKGROUND

In patients with kidney failure, living donor kidney transplantation (LDKT) is the best treatment option; yet, LDKT rates have stagnated in Canada and vary widely across provinces. We aimed to identify barriers and facilitators to LDKT in a high-performing health system.

METHODS

This study was conducted using a qualitative exploratory case study of British Columbia. Data collection, conducted between October 2020 and January 2021, entailed document review and semistructured interviews with key stakeholders, including provincial leadership, care teams and patients. We recruited participants via purposive sampling and snowballing technique. We generated themes using thematic analysis.

RESULTS

After analysis of interviews conducted with 22 participants (5 representatives from provincial organizations, 7 health care providers at transplant centres, 8 health care providers from regional units and 2 patients) and document review, we identified the following 5 themes as facilitators to LDKT: a centralized infrastructure, a mandate for timely intervention, an equitable funding model, a commitment to collaboration and cultivating distributed expertise. The relationship between 2 provincial organizations (BC Transplant and BC Renal Agency) was identified as key to enabling the mandate and processes for LDKT. Five barriers were identified that arose from silos between provincial organizations and manifested as inconsistencies in coordinating LDKT along the spectrum of care. These were divided accountability structures, disconnected care processes, missed training opportunities, inequitable access by region and financial burden for donors and recipients.

INTERPRETATION

We found strong links between provincial infrastructure and the processes that facilitate or impede timely intervention and referral of patients for LDKT. Our findings have implications for policy-makers and provide opportunities for cross-jurisdictional comparative analyses.

An Alternative Cause of Encephalopathy: Valerian Root Overdose

The interest in alternative therapeutics use has increased over the past few decades. Valerian, also known as “plant Valium,” is a popular choice as a natural remedy for insomnia or anxiety. In order to ensure patient safety, clinicians need to be knowledgeable about commonly used alternative therapeutic products, their mechanisms of action, and potential pharmacological interactions. We present an unusual case of encephalopathy due to the combination of Valerian root, a plant with putative sedating properties, along with a natural “γ-aminobutyric acid (GABA) supplement.” This case highlights the importance of thoroughly exploring alternative therapies when evaluating encephalopathy as well as the importance of being educated on the commonly used agents.

Right Atrial Perforation Leading to Cardiac Tamponade Following Veno-Venous Extracorporeal Membrane Oxygenation Cannulation

Extracorporeal membrane oxygenation (ECMO), as a supportive modality for cardiopulmonary failure, is increasing in its use due to improved advances in technology and experience lending to availability and ease of implementation. Complications with ECMO are quite common, and with increasing use, an increase in complications are a natural result. These complications can be from the underlying disease process or from the ECMO process itself, including cannula insertion. One such complication includes perforation of surrounding structures at site of insertion. We will present a case of right atrial perforation after single lumen cannula insertion, which led to development of cardiac tamponade and subsequently cardiac arrest. In addition to cannula design, lack of wire rigidity can play a role in wire migration and injury to surrounding structures. We emphasize the importance of ultrasound guidance and surveillance with echocardiogram or fluoroscopy during ECMO cannulation, regardless of cannula type, to prevent fatal complications. 

Scurvy in the Intensive Care Unit

Scurvy, caused by vitamin C deficiency, is a forgotten disease in the modern era of medicine. The prevalence of vitamin C deficiency in the United States is reported to be 7.1%. We present a case of a 56-year-old man with a history of chronic alcohol use who was admitted to the intensive care unit due to sepsis. He was found to have a rash on his hands and feet which consisted of palpable lesions as well as petechiae. Work up of the patient's skin pathology revealed ascorbic acid deficiency, also known as scurvy. This case highlights the importance of considering severe nutritional deficiency in patients with underlying alcohol use who present with skin findings that may mimic those of a vasculitis. Although rare, vitamin C deficiency still exists, and it is important to be aware of presenting signs and identify those who are at risk.

Immunoglobulin G-4-Related Retroperitoneal Fibrosis

Retroperitoneal fibrosis is caused by the replacement of normal retroperitoneal tissue with fibrosis. The majority of the cases are idiopathic, but some secondary causes include malignancy, infection, drugs, and radiotherapy. Immunoglobulin G-4 (IgG-4) related disease is a relatively newer disease and one of the rarer causes of retroperitoneal fibrosis. It usually involves the pancreas, lungs, kidneys, aorta lacrimal and salivary glands, or extrapancreatic bile duct. Elevated serum IgG-4 is the biomarker of the disease and its levels correlate with disease activity. High-dose glucocorticoid is the treatment of choice.

Cardiopulmonary resuscitation-induced consciousness

Cardiopulmonary resuscitation-induced consciousness (CPRIC) is a rare yet confusing event that can cause management issues during resuscitation. The reported incidence of CPRIC is increasing. Being aware of this phenomenon and developing a standardized approach for its management is important to prevent both delay and interruptions during resuscitation efforts. We present a patient who demonstrated purposeful movements suggesting consciousness during cardiopulmonary resuscitation that would repeatedly abate with cessation of chest compressions.

Canadian Society of Transplantation and Canadian Society of Nephrology Commentary on the 2017 KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors

Purpose of review:

To review an international guideline on the evaluation and care of living kidney donors and provide a commentary on the applicability of the recommendations to the Canadian donor population.

Sources of information:

We reviewed the 2017 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors and compared this guideline to the Canadian 2014 Kidney Paired Donation (KPD) Protocol for Participating Donors.

Methods:

A working group was formed consisting of members from the Canadian Society of Transplantation and the Canadian Society of Nephrology. Members were selected to have representation from across Canada and in various subspecialties related to living kidney donation, including nephrology, surgery, transplantation, pediatrics, and ethics.

Key findings:

Many of the KDIGO Guideline recommendations align with the KPD Protocol recommendations. Canadian researchers have contributed to much of the evidence on donor evaluation and outcomes used to support the KDIGO Guideline recommendations.

Limitations:

Certain outcomes and risk assessment tools have yet to be validated in the Canadian donor population.

Implications:

Living kidney donors should be counseled on the risks of postdonation outcomes given recent evidence, understanding the limitations of the literature with respect to its generalizability to the Canadian donor population.

Bariatric Surgery Causing Hyperammonemia

Bariatric surgery is recognized as a highly effective therapy for obesity but it does carry a risk of short term and long term complications since it results in a permanent alteration of the patient's anatomy. We present a case of 45-year-old female presented with a macular rash on extremities and facial rash from a rehabilitation center after having been discharged a month earlier from a revision surgery on her gastric bypass for anastomotic bleeding. She progressively became lethargic with Magnetic Resonance Imaging (MRI) of the brain showed symmetrically restricted diffusion concerning for hypoxic injury. Her ammonia levels were at 142 micromoles per liter (mmol/L) at the initial check which worsened to 432 mmol/L over a few days, despite treatment. Laboratory investigation later revealed her to be deficient in zinc along with many essential and nonessential amino acids. Supplemental nutrition was initiated, specifically fortifying her parenteral feeds with the essential amino acid combinations that were found deficient on testing. This lead to a slow but progressive improvement in encephalopathy. This case highlights the importance of understanding the short and long term complications of bariatric surgery. Although neurological complications are rare with peripheral neuropathy being the most common one, hyperammonemic encephalopathy is a very severe complication, with incompletely understood mechanisms and predispositions, frequently resulting in failure of recognition and subsequent delays in intervention.

Common Questions and Misconceptions in the Management of Renal Transplant Patients: A Guide for Health Care Providers in the Posttransplant Setting

Once renal transplant recipients are stabilized and require less frequent follow-up with their transplant team, health care providers outside of the transplant setting play an integral role in patients' ongoing medical care. Given renal transplant recipients' inherent complexity, these health care providers often seek consult regarding decisions that may affect transplant-related medications or outcomes. In this review, we discuss answers to 10 of the questions commonly posed to our renal transplant team by other health care providers.

A vexing case of bone pain in a renal transplant recipient: Voriconazole-induced periostitis

Immunosuppression increases the risk of opportunistic infections including fungal infections in solid organ transplant recipients. Voriconazole is used to treat invasive aspergillus infections but prolonged usage may rarely lead to periostitis. Increased plasma fluoride concentration leading to osteoblastic upregulation is thought to be the catalyst, and symptom reversal occurs with discontinuation of the offending agent. A renal transplant recipient who was on voriconazole for invasive aspergillosis developed diffuse debilitating symmetrical bone pain. Having ruled out other neurological, metabolic, and drug etiologies, voriconazole-induced periostitis was diagnosed. Increased plasma fluoride level was documented, but bone scan was non-specific. A therapeutic discontinuation of voriconazole and switch to posaconazole provided rapid symptom resolution. The patient accidently restarted voriconazole as an outpatient resulting in the same symptomology, and thus provided further evidence that this was drug related. Voriconazole-induced periostitis is a described entity in immunosuppressed solid organ transplant patients who are treated with a prolonged course of voriconazole. This case study is novel in that it demonstrates drug induced periostitis in a renal transplant recipient who developed debilitating periostitis within a short time after starting voriconazole and equally rapid resolution once it was discontinued. We conclude that patients treated with voriconazole should be routinely monitored for periostitis.

An Examination of the Application of the Kidney Donor Risk Index in British Columbia

Background:

The Kidney Donor Risk Index (KDRI) is a continuous measure of deceased donor kidney transplant failure risk that was derived in US patients based on 10 donor characteristics. In the United States, the KDRI is utilized to guide organ allocation and to inform clinical decisions regarding organ acceptance.

Objective:

To examine the application of the US-derived KDRI in a large Canadian province.

Patients:

All deceased donor kidney-only transplant recipients in British Columbia (BC) between 2005 and 2014.

Methods:

We examined the predictive performance of KDRI in BC transplant recipients and compared the overall performance of KDRI with donor age alone in predicting transplant failure (from all causes including death).

Results:

Donors in BC (N = 785) were older but included no black donors and few Hepatitis C virus (HCV)-positive donors compared with the original derivation cohort of the KDRI in the United States. The KDRI was moderately predictive of transplant failure (c statistic, 0.63) and had similar predictive performance to donor age alone (c statistic, 0.64).

Conclusion:

Our findings suggest that the US-derived KDRI does not improve the prediction of kidney transplant failure compared with donor age alone in a Canadian cohort and highlight the need to determine the applicability of KDRI in different regions.

The Change in Living Kidney Donation in Women and Men in the United States (2005-2015): A Population-Based Analysis

The factors underlying the decline in living kidney donation in the United States since 2005 must be understood to inform strategies to ensure access to this option for future patients. Population-based estimates provide a better assessment of donation activity than do trends in the number of living donor transplants. Using data from the Scientific Registry of Transplant Recipients and the United States Census, we determined longitudinal changes in living kidney donation between 2005 and 2015, focusing on the effect of sex and income. We used multilevel Poisson models to adjust for differences in age, race, the incidence of ESRD, and geographic factors (including population density, urbanization, and daily commuting). During the study period, the unadjusted rate of donation was 30.1 and 19.3 per million population in women and men, respectively, and the adjusted incidence of donation was 44% higher in women (incidence rate ratio [IRR], 1.44; 95% confidence interval [95% CI], 1.39 to 1.49). The incidence of donation was stable in women (IRR, 0.95; 95% CI, 0.84 to 1.07) but declined in men (IRR, 0.75; 95% CI, 0.68 to 0.83). Income was associated with longitudinal changes in donation in both sexes, yet donation was stable in the highest two population income quartiles in women but only in the highest income quartile in men. In both sexes, living related donations declined, irrespective of income. In conclusion, living donation declined in men but remained stable in women between 2005 and 2015, and income appeared to have a greater effect on living donation in men.

Variation in Dialysis Exposure Prior to Nonpreemptive Living Donor Kidney Transplantation in the United States and Its Association With Allograft Outcomes

BACKGROUND

The impact of dialysis exposure before nonpreemptive living donor kidney transplantation on allograft outcomes is uncertain.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Adult first-time recipients of kidney-only living donor transplants in the United States who were recorded within the Scientific Registry of Transplant Recipients for 2000 to 2016.

FACTORS

Duration of pretransplantation dialysis exposure.

OUTCOMES

Kidney transplant failure from any cause including death, death-censored transplant failure, and death with allograft function.

RESULTS

Among the 77,607 living donor transplant recipients studied, longer pretransplantation dialysis exposure was independently associated with progressively higher risk for transplant failure from any cause, including death beginning 6 months after transplantation. Compared with patients with 0.1 to 3.0 months of dialysis exposure, the HR for transplant failure from any cause including death increased from 1.16 (95% CI, 1.07-1.31) among patients with 6.1 to 9.0 months of dialysis exposure to 1.60 (95% CI, 1.43-1.79) among patients with more than 60.0 months of dialysis exposure. Pretransplantation dialysis exposure varied markedly among centers; median exposures were 11.0 and 18.9 months for centers in the 10th and 90th percentiles of dialysis exposure, respectively. Centers with the highest proportions of living donor transplantations had the shortest pretransplantation dialysis exposures. In multivariable analysis, patients of black race, with low income, with nonprivate insurance, with less than high school education, and not working for income had longer pretransplantation dialysis exposures. Dialysis exposure in patients with these characteristics also varied 2-fold between transplantation centers.

LIMITATIONS

Why longer dialysis exposure is associated with transplant failure could not be determined.

CONCLUSIONS

Longer pretransplantation dialysis exposure in nonpreemptive living donor kidney transplantation is associated with increased risk for allograft failure. Pretransplantation dialysis exposure is associated with recipients' sociodemographic and transplantation centers' characteristics. Understanding whether limiting pretransplantation dialysis exposure could improve living donor transplant outcomes will require further study.

Evaluation of Heparin Anticoagulation Protocols in Post-Renal Transplant Recipients (EHAP-PoRT Study)

BACKGROUND

Disturbances in hemostasis are common among renal transplant recipients. Because of the risk of thromboembolism and graft loss after transplant, a prophylactic heparin protocol was implemented at St Paul's Hospital in Vancouver, British Columbia, in 2011. Therapeutic heparin is sometimes prescribed perioperatively for patients with preexisting prothrombotic conditions. There is currently limited literature on the safety and efficacy of heparin use in the early postoperative period.

OBJECTIVES

The primary objectives were to document, for patients who underwent renal transplant, the incidence of major bleeding and of thrombosis in those receiving therapeutic heparin, prophylactic heparin, and no heparin anticoagulation in the early postoperative period and to compare these rates for the latter 2 groups. The secondary objectives included a comparison of the risk factors associated with major bleeding and thrombosis.

METHODS

Adult patients who received a renal transplant at St Paul's Hospital between January 2008 and July 2013 were included in this retrospective cohort study. Electronic health records and databases were used to divide patients into the 3 heparin-use cohorts, to identify cases of major bleeding and thrombosis, and to characterize patients and events. The Fisher exact test was used for the primary outcome analysis, and descriptive statistics were used for all other outcomes.

RESULTS

A total of 547 patients were included in the analysis. Major bleeding was observed in 6 (46%) of the 13 patients who received therapeutic heparin; no cases of thrombosis occurred in these patients. Major bleeding occurred in 8 (3.0%) of the 266 patients who received prophylactic heparin and 9 (3.4%) of the 268 who received no heparin (p > 0.99). Thrombosis occurred in 1 (0.4%) and 3 (1.1%) of these patients, respectively (p = 0.62). Major bleeding occurred more frequently among patients with a low-target heparin protocol, but 61% of values for partial thromboplastin time were above target. A larger proportion of deceased-donor transplant recipients who had major bleeding were taking antiplatelet agents, relative to living-donor transplant recipients.

CONCLUSION

Therapeutic use of heparin increased the risk of bleeding among renal transplant recipients, but there were no cases of thrombosis. Prophylactic use of heparin did not increase the risk of bleeding and prevented proportionately more cases of thrombosis relative to no anticoagulation; this result supports the continued use of prophylaxis.

Two-stage, in silico deconvolution of the lymphocyte compartment of the peripheral whole blood transcriptome in the context of acute kidney allograft rejection

Acute rejection is a major complication of solid organ transplantation that prevents the long-term assimilation of the allograft. Various populations of lymphocytes are principal mediators of this process, infiltrating graft tissues and driving cell-mediated cytotoxicity. Understanding the lymphocyte-specific biology associated with rejection is therefore critical. Measuring genome-wide changes in transcript abundance in peripheral whole blood cells can deliver a comprehensive view of the status of the immune system. The heterogeneous nature of the tissue significantly affects the sensitivity and interpretability of traditional analyses, however. Experimental separation of cell types is an obvious solution, but is often impractical and, more worrying, may affect expression, leading to spurious results. Statistical deconvolution of the cell type-specific signal is an attractive alternative, but existing approaches still present some challenges, particularly in a clinical research setting. Obtaining time-matched sample composition to biologically interesting, phenotypically homogeneous cell sub-populations is costly and adds significant complexity to study design. We used a two-stage, in silico deconvolution approach that first predicts sample composition to biologically meaningful and homogeneous leukocyte sub-populations, and then performs cell type-specific differential expression analysis in these same sub-populations, from peripheral whole blood expression data. We applied this approach to a peripheral whole blood expression study of kidney allograft rejection. The patterns of differential composition uncovered are consistent with previous studies carried out using flow cytometry and provide a relevant biological context when interpreting cell type-specific differential expression results. We identified cell type-specific differential expression in a variety of leukocyte sub-populations at the time of rejection. The tissue-specificity of these differentially expressed probe-set lists is consistent with the originating tissue and their functional enrichment consistent with allograft rejection. Finally, we demonstrate that the strategy described here can be used to derive useful hypotheses by validating a cell type-specific ratio in an independent cohort using the nanoString nCounter assay.

The effect of race and income on living kidney donation in the United States

Studies of racial disparities in access to living donor kidney transplantation focus mainly on patient factors, whereas donor factors remain largely unexamined. Here, data from the US Census Bureau were combined with data on all African-American and white living kidney donors in the United States who were registered in the United Network for Organ Sharing (UNOS) between 1998 and 2010 (N=57,896) to examine the associations between living kidney donation (LKD) and donor median household income and race. The relative incidence of LKD was determined in zip code quintiles ranked by median household income after adjustment for age, sex, ESRD rate, and geography. The incidence of LKD was greater in higher-income quintiles in both African-American and white populations. Notably, the total incidence of LKD was higher in the African-American population than in the white population (incidence rate ratio [IRR], 1.20; 95% confidence interval [95% CI], 1.17 to 1.24]), but ratios varied by income. The incidence of LKD was lower in the African-American population than in the white population in the lowest income quintile (IRR, 0.84; 95% CI, 0.78 to 0.90), but higher in the African-American population in the three highest income quintiles, with IRRs of 1.31 (95% CI, 1.22 to 1.41) in Q3, 1.50 (95% CI, 1.39 to 1.62) in Q4, and 1.87 (95% CI, 1.73 to 2.02) in Q5. Thus, these data suggest that racial disparities in access to living donor transplantation are likely due to socioeconomic factors rather than cultural differences in the acceptance of LKD.

Poor seroprotection but allosensitization after adjuvanted pandemic influenza H1N1 vaccine in kidney transplant recipients

BACKGROUND

Seasonal and pandemic influenza virus infections in renal transplant patients are associated with poor outcomes. During the pandemic of 2009-2010, the AS03-adjuvanted monovalent H1N1 influenza vaccine was recommended for transplant recipients, although its immunogenicity in this population was unknown. We sought to determine the safety and immunogenicity of an adjuvant-containing vaccine against pandemic influenza A H1N1 2009 (pH1N1) administered to kidney transplant recipients.

METHODS

We prospectively enrolled 124 adult kidney transplant recipients in the fall of 2009 at two transplant centers. Cohort 1 (n = 42) was assessed before and after pH1N1 immunization, while Cohort 2 (n = 82) was only assessed post immunization. Humoral response was measured by the hemagglutination inhibition assay. Vaccine safety was assessed by adverse event reporting, graft function, and human leukocyte antigen (HLA) alloantibody measurements.

RESULTS

Cohort 1 had a low rate of baseline seroprotection to pH1N1 (7%) and a low rate of seroprotection after immunization (31%). No patient <6 months post transplant (n = 5) achieved seroprotection. Seroprotection rate was greater in patients receiving double as compared with triple immunosuppression (80% vs. 24%, P = 0.01). In Cohort 2, post-immunization seroprotection was 35%. In both cohorts, no confirmed cases of pH1N1 infection occurred. No difference was seen in estimated glomerular filtration rate before (54.3 mL/min/1.73 m(2) ) and after (53.8 mL/min/1.73 m(2) ) immunization, and no acute rejections had occurred after immunization at last follow-up. In Cohort 1, 11.9% of patients developed new anti-HLA antibodies.

CONCLUSION

An adjuvant-containing vaccine to pH1N1 provided poor seroprotection in renal transplant recipients. Receiving triple immunosuppression was associated with a poor seroresponse. Vaccination appeared safe, but some patients developed new anti-HLA antibodies post vaccination. Alternative strategies to improve vaccine responses are necessary.

Living donor age and kidney allograft half-life: implications for living donor paired exchange programs

BACKGROUND AND OBJECTIVES

Living donor paired exchange programs assume that kidneys from living donors are of comparable quality and anticipated longevity. This study determined actual allograft t(1/2) within different recipient age groups (10-year increments) as a function of donor age (5-year increments), and juxtaposed these results against the probabilities of deceased donor transplantation, and exclusion from transplantation (death or removal from the wait-list).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from the US Renal Data System (transplant dates 1988-2003 with follow-up through September 2007) were used to determine allograft t(1/2), whereas data from patients on the United Network for Organ Sharing waiting list between 2003 and 2005 (with follow-up through February 2010) were used to determine wait-list outcomes.

RESULTS

With the exception of recipients aged 18-39 years, who had the best outcomes with donors aged 18-39 years, living donor age between 18 and 64 years had minimal effect on allograft t(1/2) (difference of 1-2 years with no graded association). The probability of deceased donor transplantation after 3 years of wait-listing ranged from 21% to 66% by blood type and level of sensitization, whereas the probability of being excluded from transplantation ranged from 6% to 27% by age, race, and primary renal disease.

CONCLUSIONS

With the exception of recipients aged 18-39 years, living donor age between 18 and 64 years has minimal effect on allograft survival.

The impact of pancreas transplantation on kidney allograft survival

Whether pancreas after kidney transplantation (PAK) compromises kidney allograft survival, and what pre-PAK glomerular filtration rate (GFR) should be used to select patients for PAK is unclear. We analyzed all (n = 2776) PAK recipients in the United States between 1989 and 2007 and compared their risk of kidney failure to a comparator group of n = 13 635 young adult diabetic kidney only transplant recipients during the same time after accounting for selection bias by the use of a propensity score for PAK in a multivariate time to event analysis. In a secondary analysis, we determined the association of pre-PAK GFR with subsequent kidney allograft survival. Despite an increased risk of death early after pancreas transplantation, PAK recipients had a decreased long-term risk of kidney allograft failure compared to diabetic kidney only transplant recipients HR = 0.89; 95% CI: [0.78-1.00]; p = 0.05. An association of pre-PAK GFR with kidney survival was not evident until 3 years after pancreas transplantation, and patients with a pre-PAK GFR of 30-39 mL/min still attained 10-year post-PAK kidney survival of 69%. We conclude that PAK is associated with improved kidney allograft survival, and pre-PAK GFR 30-39 mL/min should not preclude PAK. Expanded use of PAK is warranted.

The CLEAR study: a 5-day, 3-g loading dose of mycophenolate mofetil versus standard 2-g dosing in renal transplantation

BACKGROUND AND OBJECTIVES

Adequate early mycophenolic acid (MPA) exposure is associated with lower rates of acute rejection in renal transplantation. The aim of this randomized controlled trial was to determine if higher initial mycophenolate mofetil (MMF) doses increased the proportion of patients reaching therapeutic MPA levels (30 to 60 mg.h/L) by day 5.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

De novo renal transplant patients were randomized to receive intensified dosing of MMF (1.5 g twice daily on days 1 to 5, then 1.0 g twice daily) or standard dosing (1.0 g twice daily). All recipients received tacrolimus and prednisone. Full MPA areas under the curve (AUCs) were completed on days 3 and 5, whereas a limited sampling strategy was utilized at four subsequent time points.

RESULTS

At day 5, 47.5% of the MMF 3-g arm achieved the MPA therapeutic window versus 54.4% of the MMF 2-g arm. However, MPA AUC levels were significantly higher in the 3-g arm at day 3 and 5. This resulted in a trend for fewer treated acute rejections at 6 months. Significantly more acute rejections (treated, biopsy-proven including and excluding borderline) occurred in patients with MPA AUC levels<30 mg.h/L compared with those >or=30 mg.h/L at day 5. No significant differences were seen in common adverse events.

CONCLUSIONS

A limited intensified dose of MMF increased early MPA exposure and was well tolerated. Further studies are required to determine whether limited intensified MMF dosing can reduce acute rejection.

Probability, predictors, and prognosis of posttransplantation glomerulonephritis

Glomerulonephritis (GN) is the leading cause of chronic kidney disease among recipients of renal transplants. Because modern immunosuppressive regimens have reduced the incidence of rejection-related graft loss, the probability and clinical significance of posttransplantation GN (PTGN) requires reevaluation. In this Canadian epidemiologic study, we monitored 2026 sequential renal transplant recipients whose original renal disease resulted from biopsy-proven GN (36%), from presumed GN (7.8%), or from disorders other than GN (56%) for 15 yr without loss to follow-up. Kaplan-Meier estimates of PTGN in the whole population were 5.5% at 5 yr, 10.1% at 10 yr, and 15.7% at 15 yr. PTGN was diagnosed in 24.3% of patients whose original renal disease resulted from biopsy-proven GN, compared with 11.8% of those with presumed GN and 10.5% of those with disorders other than GN. Biopsy-proven GN in the native kidney, male gender, younger age, and nonwhite ethnicity predicted PTGN. Current immunosuppressive regimens did not associate with a reduced frequency of PTGN. Patients who developed PTGN had significantly reduced graft survival (10.2 versus 69.7%; P < 0.0001). In summary, in the Canadian population, PTGN is a common and serious complication that causes accelerated graft failure, despite the use of modern immunosuppressive regimens.

Lack of benefit of early protocol biopsies in renal transplant patients receiving TAC and MMF: a randomized study

We conducted a randomized, multicenter study to determine whether treatment of subclinical rejection with increased corticosteroids resulted in beneficial outcomes in renal transplant patients receiving tacrolimus (TAC), mycophenolate mofetil (MMF) and prednisone. One hundred and twenty-one patients were randomized to biopsies at 0,1,2,3 and 6 months (Biopsy arm), and 119 to biopsies at 0 and 6 months only (Control arm). The primary endpoint of the study was the prevalence of the sum of the interstitial and tubular scores (ci + ct)> 2 (Banff) at 6 months. Secondary endpoints included clinical and subclinical rejection and renal function. At 6 months, 34.8% of the Biopsy and 20.5% of the Control arm patients had a ci + ct score >or= 2 (p = 0.07). Between months 0 and 6, clinical rejection episodes were 12 in 10 Biopsy arm patients and 8 in 8 Control arm patients (p = 0.44). Overall prevalence of subclinical rejection in the Biopsy arm was 4.6%. Creatinine clearance at 6 months was 72.9 +/- 21.7 in the Biopsy and 68.90 mL/min +/- 18.35 mL/min in the Control arm patients (p = 0.18). In conclusion, we found no benefit to the procurement of early protocol biopsies in renal transplant patients receiving TAC, MMF and prednisone, at least in the short term. This is likely due to their low prevalence of subclinical rejection.

Nephrectomy after transplant failure: current practice and outcomes

The role of transplant nephrectomy after transplant failure is uncertain. We report the use and consequences of transplant nephrectomy among 19 107 transplant failure patients between 1995 and 2003 in the United States. Among 3707 patients with early transplant failure (graft survival <12 m), nephrectomy was performed in 56%, and was associated with an increased risk of death (HR 1.13, 95% CI 1.01-1.26). In contrast, among 15,400 patients with late transplant failure (graft survival > or =12 m), nephrectomy was performed in 27%, and was associated with a decreased risk of death (HR 0.89, 95% CI 0.83-0.95). In early transplant failure patients, nephrectomy was associated with a lower risk of repeat transplant failure (HR 0.72, 95% CI 0.56-0.94), while among late transplant failure patients; nephrectomy was associated with a higher risk of repeat transplant failure (HR 1.20, 95% CI 1.02-1.41). Definitive conclusions are not possible from this observational study. The role of nephrectomy in the management of dialysis treated transplant failure patients, and the implications of nephrectomy for repeat transplantation should be further studied in prospective studies.

The Older Living Kidney Donor: Part of the Solution to the Organ Shortage

BACKGROUND

Strategies to increase kidney transplantation are urgently needed.

METHODS

We studied all (n = 73,073) first kidney-only transplant recipients in the United States between 1995 and 2003 to determine the incidence and outcomes of living donor transplantation as a function of donor age. Because 90% of living donors were <55 years, we defined older living donors as > or =55 years. Factors associated with transplantation from older living donors and the association of living donor age with allograft function and survival were determined.

RESULTS

Recipients of older age, female gender, white race, and preemptive transplants had higher odds of older living donor transplantation. Older living donor transplantation was more likely from spousal donors rather than blood relatives, and more likely when a husband was the donor. The glomerular filtration rate (GFR) one year after transplantation decreased with increasing donor age (P < 0.001). Graft survival from living donors > or =55 years was 85% and 76% at three and five years (compared to 89% and 82% with living donors <55 years, and 82% and 73% with deceased donors <55 years). In a multivariate model, the risk of graft loss with living donors 55-64 years was similar to that with deceased donors <55 years, while recipients from living donors 65-69 years (HR = 1.3, 95% CI: 1.1-1.7) and >70 years (HR = 1.7, 95% CI: 1.1-2.6) had a higher relative risk of graft loss.

CONCLUSIONS

Outcomes are excellent with living donors <65 years. Expanded use of older living donors may help meet the demand for transplantation.

The impact of waiting time and comorbid conditions on the survival benefit of kidney transplantation

BACKGROUND

Longer waiting times may limit the survival benefit of kidney transplantation in older patients or those with a high burden of comorbid disease.

METHODS

We performed a longitudinal study of mortality among 63,783 transplant candidates who started dialysis between April 1995 and December 2000. We determined the relative risk (RR) of death and increase in life expectancy among subjects who received a first deceased donor transplant after different waiting times compared to subjects who had equivalent waiting times but remained on dialysis.

RESULTS

Transplant recipients had a lower long-term RR of death and the risk reduction was greatest in recipients with longer waiting times (RR of death 12 months after transplantation for recipients with waiting times of 0, 1, 2, 3 years was 0.49, 0.43, 0.38, 0.34, P = 0.0006). The average increase in life expectancy in transplant recipients was 9.8 years and was lower in older recipients and recipients with comorbid conditions. Increased waiting times from 1 to 3 years only moderately decreased the overall survival benefit of transplantation from 7.1 to 5.6 years, and all subjects derived a survival benefit from transplantation with waiting times up to 3 years.

CONCLUSION

These findings do not support limiting access to transplantation for otherwise suitable candidates on the basis of longer anticipated waiting times.

Cardiovascular events and investigation in patients who are awaiting cadaveric kidney transplantation

The optimal strategy for cardiovascular (CV) disease surveillance in kidney transplant candidates is uncertain. In this observational study of 604 wait-listed patients in British Columbia, the risk for CV event in diabetic and nondiabetic candidates was 12.7 and 4.5% per year, respectively. CV event rates were relatively constant during the first 3 yr of wait-listing (5.3 to 6.6 per 100 patient-years; 95% confidence interval [CI], 3.7 to 9.3) but rose dramatically during the peritransplantation period (39.6/100 patient-years; 95% CI, 20.6 to 76.1) and remained high throughout the first posttransplantation year (4.0 per 100 patient-years; 95% CI, 2.2 to 7.5). The results of noninvasive cardiac investigations before wait-listing were not predictive of the time to CV event after wait-listing. The practice of surveillance cardiac investigation in wait-listed patients on the basis of ongoing clinical assessment of cardiac risk resulted in fewer investigations (n = 171) than with the recommended practice of periodic screening on the basis of waiting time alone (n = 530) and was not associated with an increased frequency of CV events (CV event rate in patients with and without the recommended frequency of investigation was 9.9 [95% CI, 7.1 to 13.7] and 6.7 [95% CI, 5.2 to 8.7] per 100 patient-years). It is concluded that transplant candidates are at high risk for CV events particularly during the perioperative period. Initial cardiac investigations have limited value in guiding the timing of patient reevaluation after wait-listing. Periodic surveillance cardiac investigation after wait-listing may be unnecessary and requires further study.

Probability of mortality of critically ill cancer patients at 72 h of intensive care unit (ICU) management

GOALS

To develop and validate a model for probability of hospital mortality for cancer patients at 72 h of intensive care unit (ICU) management.

PATIENTS AND METHODS

This is an inception cohort study performed at four ICUs of academic medical centers in the United States. Defined continuous and categorical variables were collected on consecutive patients with cancer admitted to the ICU. A preliminary model was developed from 827 patients and then validated on an additional 415 patients. Multiple logistic regression modeling was used to develop the models, which were subsequently evaluated for discrimination and calibration. The main outcome measure is in-hospital death.

RESULTS

A probability of mortality model, which incorporates ten discrete categorical variables, was developed and validated. All variables were collected at 72 h of ICU care. Variables included evidence of disease progression, performance status before hospitalization, heart rate >100 beats/min, Glasgow coma score </=5, mechanical ventilation, arterial oxygen pressure/fractional inspiratory oxygen ( PaO(2)/FiO(2)) ratio <250, platelets <100 k/ micro l, serum bicarbonate (HCO(3))<20 mEq/l, blood urea nitrogen (BUN) >40 mg/dl, and a urine output of <150 ml for any 8 h in the previous 24 h. The p values for the fit of the preliminary and validation models were 0.535 and 0.354 respectively, and the areas under the receiver operating characteristic (ROC) curves were 0.809 and 0.820.

CONCLUSIONS

We report a multivariable logistic regression model to estimate the probability of hospital mortality in critically ill cancer patients at 72 h of ICU care. The model is comprised of ten unambiguous and readily available variables. When used in conjunction with clinical judgment, this model should improve discussions about goals of care of these patients. Additional validation in a community hospital setting is warranted.

A pilot study of steroid-free immunosuppression in the prevention of acute rejection in renal allograft recipients

BACKGROUND

Corticosteroids have been a mainstay of rejection prophylaxis for several decades, despite the multiple adverse effects of long-term use, including weight gain, hyperlipidemia, diabetes, hypertension, and bone disease. The detrimental effect of steroids on the metabolic profile begins in the early posttransplantation period, and the complete avoidance of steroids in transplantation would therefore be optimal. We hypothesized that the addition of mycophenolate mofetil (MMF) and a humanized monoclonal anti-CD25 antibody (daclizumab) to a cyclosporine (CsA microemulsion)-based immunosuppression protocol would permit transplantation without steroids.

METHODS

Steroid-free renal transplantation was attempted in 57 patients treated with daclizumab, MMF, and CsA. Twenty-eight patients received kidneys from living donors; the remaining 29 received cadaveric grafts.

RESULTS

At 1 year, patient and graft survival were 95% and 89%, respectively. Fourteen patients (25%) experienced rejections, of which 13 were readily reversed with steroids; 1 patient required OKT3. Mean serum creatinine at 12 months for patients not experiencing rejection was 149+/-58 micromol/L, compared with 158+/-102 micromol/L for those experiencing rejection. Five patients required hospitalization for infection; no patients developed lymphoproliferative disease. At baseline, 17 patients required 3 or more antihypertensive medications, compared with 2 patients at 1 year. Three of 43 nondiabetic patients developed diabetes during the study. There was no significant reduction in lumbar or femoral bone density.

CONCLUSIONS

On the basis of these positive results, we believe steroid avoidance with this immunosuppressive regimen merits further study.

Lack of long-term benefits of steroid withdrawal in renal transplant recipients

Glucocorticoids used in renal transplantation have been associated with numerous adverse effects. Most studies that showed short-term benefits of steroid withdrawal made comparisons for patients administered prednisone, 10 to 17.5 mg/d, versus no prednisone. Few have studied long-term benefits of steroid withdrawal. We performed a retrospective review and identified 58 patients administered cyclosporine, azathioprine, and prednisone who underwent complete steroid withdrawal. Post-steroid withdrawal follow-up was 7.6 +/- 1.9 years. Nine patients restarted prednisone therapy, 3 patients lost their grafts (2 of those restarted on prednisone therapy), and 2 patients died with functioning grafts. When prednisone dosage was tapered from 10 mg/d to 10 mg every other day, clinically significant improvements were seen in weight, systolic and diastolic blood pressure, blood pressure medications, glycosylated hemoglobin level, and diabetic medications. No further benefits were seen in these parameters and total cholesterol level on complete steroid withdrawal from prednisone, 10 mg every other day. Most of the earlier benefits were not sustained on long-term follow-up, and the increase in these parameters was similar to that of a similar matched control group (that underwent transplantation during the same period) maintained on prednisone, 5 mg/d. Major differences were decreases in creatinine clearances and hemoglobin levels, which were greater in the steroid-withdrawal group (7.4 +/- 1.9 mL/min and 1.2 +/- 0.2 g/dL, respectively) compared with the control group (2.6 +/- 1.5 mL/min and 0.5 +/- 0.2 g/dL, respectively). In conclusion, most of the metabolic benefits were seen with steroid dosage taper from prednisone, 10 mg/d to 10 mg every other day, with no further benefits with steroid withdrawal. Most of these benefits were not sustained on long-term follow-up, questioning the utility of steroid withdrawal.

Screening for basiliximab exposure-response relationships in renal allotransplantation

The immunosuppressant basiliximab--a chimeric monoclonal antibody specific to the interleukin-2 receptor on activated T-lymphocytes--significantly reduces the incidence of acute cellular rejection following renal transplantation. Screening for exposure-response relationships was performed within a randomized, blinded, placebo-controlled efficacy trial in which patients received 40 mg basiliximab (20 mg on days 0 and 4) by intravenous infusion in addition to cyclosporine and corticosteroids. In a subset of patients, serum samples were collected pre-transplant and once in weeks 2, 3 and 4 for determination of basiliximab concentrations. A population pharmacostatistical model was used to derive individual empirical Bayes estimates of each patient's pharmacokinetic parameters. Biopsy-confirmed acute rejection episodes were recorded to month 6 post-transplant. Forty basiliximab-treated patients were evaluated, 30 men and 10 women, aged 48 +/- 12 yr (range, 24-73) and weighing 72.4 +/- 12.9 kg (range, 52.5-107.5). The basiliximab distribution volume was 7.5 +/- 1.7 L, the half-life 7.5 +/- 2.5 d and the clearance 33 +/- 12 mL/h. There was no clinically relevant influence of weight, age, or gender on basiliximab disposition. Receptor-saturating serum basiliximab concentrations (> 0.2 microgram/mL) were maintained for 41 +/- 23 d. Twenty-five patients remained rejection-free over the 6-month observation period, while a total of 26 biopsy-confirmed acute rejection episodes occurred in the remaining 14 patients. Of these episodes, 12 occurred during receptor blockade. No apparent relationship to basiliximab concentration on the day of onset was observed range, 0.1-9.0 microgram/mL) nor did the time of suppression offset represent a period of increased risk for rejection episodes. Fourteen rejection episodes occurred after basiliximab had cleared from the serum. The durations of receptor suppression preceding these events did not differ compared with those in patients who remained rejection-free: 32 +/- 11 versus 45 +/- 26 d, respectively (p = 0.1269). Given the durations of receptor saturation achieved with the chosen basiliximab regimen, this screen for exposure-response relationships did not identify the duration of receptor saturation in peripheral blood as a predictive factor for acute rejection episodes. Further exploration for exposure-effect relationships in a larger population is warranted.

Safety and tolerability of cyclosporine and cyclosporine microemulsion during 18 months of follow-up in stable renal transplant recipients: a report of the Canadian Neoral Renal Study Group

BACKGROUND

There has been concern that the increased drug exposure associated with treatment with cyclosporine microemulsion (CsA-ME) would lead to an increase in adverse events.

METHODS

The long-term safety and tolerability of conventional cyclosporine (CsA) and CsA-ME were compared in a randomized, multicenter, pharmacoepidemiologic study involving 1097 stable renal transplant patients after 18 months of follow-up.

RESULTS

No significant difference was seen in change in serum creatinine or calculated creatinine clearance between the two groups. Episodes of deterioration in renal function (change in serum creatinine > or = 20%) were categorized with the following results for CsA-ME versus CsA, respectively: acute rejection, 4.5% vs. 4.5%; chronic rejection, 8% vs. 11%; CsA nephrotoxicity, 12% vs. 7% (P=0.008); transient changes, 17% vs. 12%; other causes, 4% vs. 6%. During the first 6 months of the study, a transient increase in the incidence of gastrointestinal and neurological adverse events was seen in the CsA-ME group compared with the CsA group. Up to 18 months, patients in the CsA group reported significantly fewer hearing and vestibular disorders, but more cardiovascular problems than those in the CsA-ME group (P=0.035).

CONCLUSIONS

Tolerance to CsA and CsA-ME was similar. Renal function over 18 months was not adversely affected by the increased drug exposure with CsA-ME, although there was a transient increase in nephrotoxicity. The frequency of acute and chronic rejection did not change.

Investigation of a possible interaction between ciprofloxacin and cyclosporine in renal transplant patients

BACKGROUND

Bacterial infection is a common complication during the first few months after renal transplantation. Ciprofloxacin, a fluoroquinolone broad-spectrum antibiotic, is used frequently in treating infections in the early posttransplant period. Evidence from in vitro studies has suggested that ciprofloxacin can antagonize the cyclosporine (CsA)-dependent inhibition of interleukin-2 production. Such an effect in renal transplant patients could antagonize the immunosuppressive activity of CsA and lead to rejection of the graft.

METHODS

To investigate the possibility of a pharmacodynamic interaction between ciprofloxacin and CsA, we conducted a case-control study in 42 patients who had received a kidney transplant and who were prescribed ciprofloxacin in the first 1-6 months after transplantation and in their matched controls (two per case) who did not receive ciprofloxacin during the study period.

RESULTS

There was a twofold greater incidence (P=0.008) of ciprofloxacin use at 1-3 months (65%) than was observed at 4-7 months (35%) after transplantation. The proportion of cases experiencing at least one episode of biopsy-proven rejection 1-3 months posttransplant (45%) was significantly greater (P=0.004) than that of controls (19%). Furthermore, there was a marked increase (P<0.001) in the incidence of rejection temporally associated with ciprofloxacin use among cases (29%) compared with that experienced by the controls (2%).

CONCLUSIONS

The possibility that ciprofloxacin increases rejection rates in renal transplant patients may be of clinical importance and therefore warrants further investigation.

A randomized, prospective multicenter pharmacoepidemiologic study of cyclosporine microemulsion in stable renal graft recipients. Report of the Canadian Neoral Renal Transplantation Study Group

BACKGROUND

The safety, tolerability, and pharmacokinetics of conventional cyclosporine (ConCsA) and cyclosporine microemulsion (MeCsA) were compared under conditions of normal clinical practice in a prospective, randomized, concentration-controlled, pharmacoepidemiologic study.

METHODS

Between September 1994 and March 1995, 1097 stable renal transplant recipients in 14 Canadian centers were randomized 2:1 to treatment with MeCsA or ConCsA. Patients were commenced on each study drug at a dose equal to their previous therapy with ConCsA, and the dose was adjusted to maintain predose whole blood cyclosporine concentrations within the therapeutic range established for each center. Prednisone and azathioprine were continued unless dose adjustment was required for clinical reasons.

RESULTS

The mean cyclosporine concentration was comparable in both treatment groups at all time points throughout the 6 months of follow-up. The mean dose of cyclosporine was 3.6 mg/kg/day in both treatment groups at entry to the study, and declined by 0.3% and by 2.8% in patients receiving ConCsA and MeCsA, respectively. The nature and severity of adverse events were similar in both treatment groups, but there was a transient increase in neurological and gastrointestinal complications in the group receiving MeCsA within the first month after conversion (P<0.05). Serum creatinine and creatinine clearance did not change in either treatment group throughout the study. Biopsy-proven acute rejection occurred in three patients (0.8%) receiving ConCsA and in seven patients (0.9%) receiving MeCsA, with non-histologically proven acute rejection in an additional three patients (0.8%) receiving ConCsA and five patients (0.6%) receiving MeCsA (P=NS). Serum creatinine rose transiently in 35 patients (9.8%) receiving ConCsA and 138 patients (18.7%) receiving MeCsA (P<0.05) and resolved either spontaneously or after a reduction in the cyclosporine dose. One graft was lost in the MeCsA group due to irreversible rejection, and seven patients died, three in the group receiving ConCsA and four of those receiving MeCsA (P=NS). Absorption of cyclosporine was more rapid and complete from MeCsA than from ConCsA during the first 4 hr of the dosing interval, resulting in almost 40% greater exposure to the drug (P<0.001). There was close correlation between area under the time-concentration curve (AUC) over the first 4 hr of the 12-hr dosage interval and AUC over the entire 12-hr dosage interval for both formulations, making AUC over the first 4 hr a good predictor of total cyclosporine exposure. Using this parameter, patients with low absorption randomized to receive MeCsA showed a marked increase in drug exposure by months 3 and 6, whereas there was no change in those who continued on ConCsA. A limited sampling strategy utilizing samples at the predose and postdose trough levels provided an excellent correlation with drug exposure, particularly for patients receiving MeCsA (r2=0.94 MeCsA vs. r2=0.89 ConCsA).

CONCLUSIONS

MeCsA appears to be a safe and effective therapy in stable renal transplant patients and provides superior and more consistent absorption of cyclosporine when compared with ConCsA. Transient toxicity after conversion to MeCsA occurs in some patients, and may reflect the increased exposure to cyclosporine. Use of a limited sampling approach combining trough and 2-hr postdose concentrations may provide an effective way to monitor this exposure.