Creatinine-based estimation of rate of long term renal function loss in lung transplant recipients. Which method is preferable?

Estimating Renal Function Following Lung Transplantation

Background: Patients undergoing lung transplantation (LTx) experience a rapid decline in glomerular filtration rate (GFR) in the acute postoperative period. However, no prospective longitudinal studies directly comparing the performance of equations for estimating GFR in this patient population currently exist. Methods: In total, 32 patients undergoing LTx met the study criteria. At pre-LTx and 1-, 3-, and 12-weeks post-LTx, GFR was determined by ⁵¹Cr-EDTA and by equations for estimating GFR based on plasma (P)-Creatinine, P-Cystatin C, or a combination of both. Results: Measured GFR declined from 98.0 mL/min/1.73 m² at pre-LTx to 54.1 mL/min/1.73 m² at 12-weeks post-LTx. Equations based on P-Creatinine underestimated GFR decline after LTx, whereas equations based on P-Cystatin C overestimated this decline. Overall, the 2021 CKD-EPI combination equation had the lowest bias and highest precision at both pre-LTx and post-LTx. Conclusions: Caution must be applied when interpreting renal function based on equations for estimating GFR in the acute postoperative period following LTx. Simplified methods for measuring GFR may allow for more widespread use of measured GFR in this vulnerable patient population.

Long-term clinical outcomes of patients with nonsignificant transplanted renal artery stenosis

Background

Transplant renal artery stenosis (TRAS) is the main vascular complication of kidney transplantation. For research and treatment purposes, several authors consider critical renal artery stenosis to be greater than 50%, and percutaneous intervention is indicated in this scenario. However, there are no reports in the current literature on the evolution of patients with less than 50% stenosis.

Method

This retrospective study included data from all patients who underwent kidney transplantation and were suspected of having TRAS after transplantation with stenosis under 50% independent of age and were referred for angiography at a single centre between January 2007 and December 2014.

Results

During this period, 6,829 kidney transplants were performed at Hospital do Rim, 313 of whom had a clinical suspicion of TRAS, and 54 of whom presented no significant stenosis. The average age was 35.93 years old, the predominant sex was male, and most individuals (94.4%) underwent dialysis before transplantation. In most cases in this group, transplants occurred from a deceased donor (66.7%). The time between transplantation and angiography was less than one year in 79.6% of patients, and all presented nonsignificant TRAS. Creatinine levels, systolic blood pressure, diastolic blood pressure and glomerular filtration rate improved over the long term. The outcomes found were death and allograft loss.

Conclusion

Age, sex and ethnic group of patients were factors that did not interfere with the frequency of renal artery stenosis. The outcomes showed that in the long term, most patients evolve well and have improved quality of life and kidney function, although there are cases of death and kidney loss.

Assessment of kidney function: clinical indications for measured GFR

In the vast majority of cases, glomerular filtration rate (GFR) is estimated using serum creatinine, which is highly influenced by age, sex, muscle mass, body composition, severe chronic illness and many other factors. This often leads to misclassification of patients or potentially puts patients at risk for inappropriate clinical decisions. Possible solutions are the use of cystatin C as an alternative endogenous marker or performing direct measurement of GFR using an exogenous marker such as iohexol. The purpose of this review is to highlight clinical scenarios and conditions such as extreme body composition, Black race, disagreement between creatinine- and cystatin C-based estimated GFR (eGFR), drug dosing, liver cirrhosis, advanced chronic kidney disease and the transition to kidney replacement therapy, non-kidney solid organ transplant recipients and living kidney donors where creatinine-based GFR estimation may be invalid. In contrast to the majority of literature on measured GFR (mGFR), this review does not include aspects of mGFR for research or public health settings but aims to reach practicing clinicians and raise their understanding of the substantial limitations of creatinine. While including cystatin C as a renal biomarker in GFR estimating equations has been shown to increase the accuracy of the GFR estimate, there are also limitations to eGFR based on cystatin C alone or the combination of creatinine and cystatin C in the clinical scenarios described above that can be overcome by measuring GFR with an exogenous marker. We acknowledge that mGFR is not readily available in many centres but hope that this review will highlight and promote the expansion of kidney function diagnostics using standardized mGFR procedures as an important milestone towards more accurate and personalized medicine.

Acute Kidney Disease After Liver and Heart Transplantation

After transplantation of nonrenal solid organs, an acute decline in kidney function develops in the majority of patients. In addition, a significant number of nonrenal solid organ transplant recipients develop chronic kidney disease, and some develop end-stage renal disease, requiring renal replacement therapy. The incidence varies depending on the transplanted organ. Acute kidney injury after nonrenal solid organ transplantation is associated with prolonged length of stay, cost, increased risk of death, de novo chronic kidney disease, and end-stage renal disease. This overview focuses on the risk factors for posttransplant acute kidney injury after liver and heart transplantation, integrating discussion of proteinuria and chronic kidney disease with emphasis on pathogenesis, histopathology, and management including the use of mechanistic target of rapamycin inhibition and costimulatory blockade.

Prevalence and Diagnosis of Chronic Kidney Disease in Maintenance Lung Transplant Patients: ICEBERG Study

BACKGROUND

Chronic renal dysfunction (CRD) after lung transplantation (LT) is a common and noteworthy complication associated with increased morbidity and mortality rates. The study objectives were to determine the prevalence of CRD according to different diagnostic criteria and describe its therapeutic management.

METHODS

This observational, multicenter, retrospective study included LT patients with ≥ 2 years of evolution. CRD was defined according to 2 different methods: (1) by the physician's subjective clinical criteria and (2) by analytical criteria (estimated glomerular filtration rate [eGFR] by Modification of Diet in Renal Disease of ≤ 59 mL/min).

RESULTS

We included 113 patients; 65.5% were men and the mean age at transplant was 49.1 (12.6) years. At 6 months after transplant, approximately half of patients had CRD according to analytical criteria, and, at 2 years after transplantation, the prevalence rose to 80%. Although clinical prevalence and analytical prevalence were similar (68.8% and 78.6%), a weak concordance was observed (Kappa index: 0.6). Among patients who were not classified as having CRD according to clinical criteria, 40.0% (14/35) were diagnosed with CRD according to analytical criteria. None of the patients underwent renal biopsy, and 5.1% of patients required dialysis. In 77.0% of patients with clinical CRD diagnosis, the immunosuppressive regimen was modified: reduction of isolated calcineurin inhibitors (CNIs) (35.0%), CNIs decreased with mycophenolic acid change (23.3%), and CNIs lowering with mammalian target of rapamycin introduction (6.7%). In a multivariate logistic regression model, the independent factors associated with CRD were an older recipient age, low body mass index (BMI) at transplant, treatment with cyclosporine/azathioprine, and low eGFR at the first month after transplant.

CONCLUSIONS

We found a high incidence of CRD at the first year after transplantation, which increased subsequently. Moreover, CRD was considerably underestimated by physicians' subjective clinical criteria. End points related to CRD development were older age, low BMI, azathioprine use, and low eGFR during the first month after transplant. The latter finding provides an opportunity to implement prevention strategies.

Risk factors for native kidney dysfunction in patients with abdominal multivisceral/small bowel transplantation

Kidney dysfunction is a recognized complication after non-renal solid organ transplantation, particularly after intestinal transplant. In our study, we reviewed data on 33 multivisceral transplant (MVT)- and 15 isolated small bowel (ISB)-transplant patients to determine risk factors for kidney dysfunction. Kidney function was estimated by modified diet in renal disease (MDRD) and Schwartz formula for adults and children, respectively. Acute kidney injury (AKI) was defined as an increase in the serum Cr (sCr) greater than twofold. Kidney function declined significantly at one yr after transplantation with 46% of subjects showing an estimated GFR (eGFR) <60 mL/min. Patients with an episode of AKI were more likely to have reduced eGFR than those without AKI (p < 0.025). In linear regression analyses, age, pre-transplant sCr, eGFR at postoperative day (POD) 30, 90, 180, 270, and tacrolimus level at POD 7 showed significant correlation with one yr post-transplant eGFR (p < 0.05). Pediatric patients and patients with MVT had lesser decline in kidney function compared with adults or patients with ISB. In conclusion, risk factors for post-transplant kidney dysfunction in intestinal transplantation included age, pre-transplant sCr, AKI episode, eGFR at POD 30, 90, 180, 270, and tacrolimus level at POD 7.

Former smoking is a risk factor for chronic kidney disease after lung transplantation

Chronic kidney disease (CKD) is a common complication after lung transplantation (LTx). Smoking is a risk factor for many diseases, including CKD. Smoking cessation for >6 months is required for LTx enlistment. However, the impact of smoking history on CKD development after LTx remains unclear. We investigated the effect of former smoking on CKD and mortality after LTx. CKD was based on glomerular filtration rate (GFR) ((125) I-iothalamate measurements). GFR was measured before and repeatedly after LTx. One hundred thirty-four patients never smoked and 192 patients previously smoked for a median of 17.5 pack years. At 5 years after LTx, overall cumulative incidences of CKD-III, CKD-IV and death were 68.5%, 16.3% and 34.6%, respectively. Compared to never smokers, former smokers had a higher risk for CKD-III (hazard ratio [HR] 95% confidence interval [95%CI]= 1.69 [1.27-2.24]) and IV (HR = 1.90 [1.11-3.27]), but not for mortality (HR = 0.99 [0.71-1.38]). Adjustment for potential confounders did not change results. Thus, despite cessation, smoking history remained a risk factor for CKD in LTx recipients. Considering the increasing acceptance for LTx of older recipients with lower baseline renal function and an extensive smoking history, our data suggest that the problem of post-LTx CKD may increase in the future.

Age, gender, and body mass index are associated with renal function after kidney donation

Renal function is thoroughly evaluated before live kidney donation. However, some donors experience impaired recovery of renal function after donation. Our aim was to assess estimated glomerular filtration rate (eGFR) and mean relative (%) increase in creatinine one yr after donor nephrectomy. The study was based on retrospective data from kidney donors during the period 1997-2009. Pre-operative and one-yr follow-up data were available for 721 of 1067 donors. Mean relative increase in creatinine and eGFR were stratified by gender, body mass index (BMI), and age at donation. At one yr post-donation, overweight (BMI > 5 kg/m(2) ) women 50 yr or older experienced the lowest eGFR of 49.6 ± 8.8 mL/min/1.73 m(2) . Men younger than 50 yr with normal weight (BMI < 25 kg/m(2) ) had the highest eGFR of 66.6 ± 10.4 mL/min/1.73 m(2) . Overweight men 50 yr or older had the highest relative increase in creatinine of 49.4% compared to pre-donation. Men under 50 yr with normal weight had the smallest increase in creatinine of 35.2%. In multivariate analysis, older age (p < 0.001), male gender (p < 0.001), and overweight (p = 0.01) were associated with relative increase in creatinine after donation. Potential donors should be offered counseling regarding overweight, as this is a modifiable risk factor.

Cardiovascular risk factor treatment targets and renal complications in high risk vascular patients: a cohort study

BACKGROUND

To determine if recommended treatment targets, as specified in clinical practice guidelines for the management of cardiovascular disease, reduces the risk of renal complications in high risk patient populations.

METHODS

This was a cohort study. Participants in Utrecht, The Netherlands either at risk of, or had cardiovascular disease were recruited. Cardiovascular treatment targets were achievement of control in systolic and diastolic blood pressure, total and low-density cholesterol, and treatment of albuminuria. Outcome measures were time to development of end stage renal failure or symptomatic renal atherosclerotic disease requiring intervention.

RESULTS

The cohort consisted of 7,208 participants; 1,759 diabetics and 4,859 with clinically manifest vascular disease. The median age was 57 years and 67% were male. Overall, 29% of the cohort achieved the treatment target for systolic blood pressure, 39% for diastolic blood pressure, 28% for total cholesterol, 31% for LDL cholesterol and 78% for albuminuria. The incidence rate for end stage renal failure and renal atherosclerotic disease reduced linearly with each additional treatment target achieved (p value less than 0.001). Achievement of any two treatment targets reduced the risk of renal complications, hazard ratio 0.46 (95% CI 0.26-0.82). For patients with clinically manifest vascular disease and diabetes, the hazard ratios were 0.56 (95% CI 0.28 - 1.12) and 0.28 (95%CI 0.10 - 0.79) respectively.

CONCLUSION

Clinical guidelines for cardiovascular disease management do reduce risk of renal complications in high risk patients. Benefits are seen with attainment of any two treatment targets.

Renal disease in systemic sclerosis with normal serum creatinine

Prognosis of systemic sclerosis largely depends on involvement of internal organs. The aim was to evaluate renal impairment in patients with systemic sclerosis by measuring the Glomerular filteration rate (GFR) and then calculating the GFR using the Cockgroft and Gault formula and the Modification of Diet in Renal Disease Equation (MDRD) formula. Thirty one scleroderma patients were recruited from the Rheumatology and Rehabilitation Department, Cairo University Hospitals, mean age 43.25 +/- 11.28 years, 31 healthy controls were included. Disease severity was done using Medsger score. GFR was measured using classical Gates method TC99mDTPA. The modified Cockcroft and Gault formula and equation 7 from the MDRD were used for calculation of GFR. All patients had within normal serum creatinine levels. A normal GFR (>89ml/min) was found in 45.1%. Gates method showed reduced GFR was reported in 54.9%. Stage II chronic kidney disease (60-89 ml/min) found 32.3%, and stage III (30-59 ml/min) in 22.6%. The formulae used showed reduction of GFR in 35.29% of those affected by the Cockcroft-Gault and in 41.17% of those affected using the MDRD. No correlation to patients' age, disease duration, or severity. A positive correlation was also reported between the presence of renal involvement and pulmonary vascular involvement p = 0.04. Gates method showed reduction of the GFR in 54.9% of the systemic sclerosis patients. The formulae used were not as precise as the measured GFR in diagnosing all cases with subclinical renal involvement. Patients with systemic sclerosis should be screened for renal involvement irrespective of disease severity or duration.

[Medical complications of lung transplantation]

In 2010, lung transplantation is a valuable therapeutic option for a number of patients suffering from of end-stage non-neoplastic pulmonary diseases. The patients frequently regain a very good quality of life, however, long-term survival is often hampered by the development of complications such as the bronchiolitis obliterans syndrome, metabolic and infectious complications. As the bronchiolitis obliterans syndrome is the first cause of death in the medium and long term, an intense immunosuppressive treatment is maintained for life in order to prevent or stabilize this complication. The immunosuppression on the other hand induces a number of potentially severe complications including metabolic complications, infections and malignancies. The most frequent metabolic complications are arterial hypertension, chronic renal insufficiency, diabetes, hyperlipidemia and osteoporosis. Bacterial, viral and fungal infections are the second cause of mortality. They are to be considered as medical emergencies and require urgent assessment and targeted therapy after microbiologic specimens have been obtained. They should not, under any circumstances, be treated empirically and it has also to be kept in mind that the lung transplant recipient may present several concomitant infections. The most frequent malignancies are skin cancers, the post-transplant lymphoproliferative disorders, Kaposi's sarcoma and some types of bronchogenic carcinomas, head/neck and digestive cancers. Lung transplantation is no longer an exceptional procedure; thus, the pulmonologist will be confronted with such patients and should be able to recognize the symptoms and signs of the principal non-surgical complications. The goal of this review is to give a general overview of the most frequently encountered complications. Their assessment and treatment, though, will most often require the input of other specialists and a multidisciplinary and transversal approach.

Renal histopathological lesions after lung transplantation in patients with cystic fibrosis

We have analyzed the evolution of renal status beyond the perioperative period in patients with cystic fibrosis (CF) undergoing lung transplantation and presented histological analysis of 15 patients biopsied for an episode of accelerated renal function loss (RFL). Episodes of accelerated RFL after the perioperative period occurred in 32.5% of patients and significantly raised the risk of end-stage renal disease (ESRD) (p < 0.001). The histologic lesions associated with these episodes differed according to the time of onset. Early onset (10 cases) was associated with tubulointerstitial lesions in the form of oxalate nephropathy (50%) and/or a pigmented tubulopathy (80%). This latter was correlated with treatment with antiviral agents (p = 0.002) and aminoside and glycopeptide antibiotics (p = 0.03) administered in the month preceding biopsy. Lesions in late episodes of accelerated RFL (5 cases) were principally vascular: arteriosclerosis and arteriolosclerosis (p = 0.007, p = 0.00002), correlated with diabetic glomerulosclerosis or focal segmental glomerulosclerosis in the absence of prominent diabetic changes. Specific calcineurin-inhibitor nephrotoxicity was present in 93.3% of biopsies associated with thrombotic microangiopathy in 46.7% of cases. The identification of specific etiologies of progressive kidney disease in patients with CF after lung transplantation should permit more effective post-transplant care of these patients.

Chronic kidney disease after nonrenal solid-organ transplantation

Chronic kidney disease (CKD) is a common complication after nonrenal solid-organ transplantation. The risk for CKD is influenced by many factors, some of which have a direct impact on how such patients are treated in the pre-, peri-, and posttransplantation settings. This review describes hazards for acute and chronic kidney injury, with particular emphasis on calcineurin inhibitor-mediated nephrotoxicity. Rather than a detailed description of management issues that are common to the general CKD population, highlighted are aspects that are more specific to nonrenal solid-organ transplant recipients with a focus on liver, heart, and lung recipients. Strategies to minimize nephrotoxic insults and retard progressive renal injury are discussed, as are issues that are pertinent to dialysis and transplantation. Finally, future approaches to prevent and treat CKD without compromising function of the transplanted organ are addressed.

Initial Single-Center Experience With Sirolimus After Lung Transplantation

BACKGROUND

Standard immunosuppression after lung transplantation includes calcineurin inhibitors, mycophenolate mofetil, and steroids. Long-term survivors of lung transplantation are often confronted with chronic kidney disease, by definition related to the intake of calcineurin inhibitors. Sirolimus has been increasingly proposed as an alternative immunosuppressive agent due to its absence of nephrotoxicity, which could be used in selected patients.

METHODS

We prospectively administered sirolimus as an alternative to calcineurin inhibitors in 10 lung transplantation recipients with persistent drug nephrotoxicity. They were switched from tacrolimus to sirolimus. Four patients also had bronchiolitis obliterans syndrome. The conversion scheme consisted of an immediate stop of tacrolimus and an 6 to 8-mg loading dose of sirolimus, followed by 4 mg/d. After 5 days, the sirolimus dose was adjusted to maintain trough levels between 12 and 18 ng/mL or 6 and 12 ng/mL for combined sirolimus and tacrolimus. Patients were monitored for renal and graft function as well as clinical status.

RESULTS

A significant decrease in creatinine was observed after 1 week of treatment (P = .011). Azotemia decreased after 1 month, remaining stable (P < .01). Pulmonary function tests did not show significant modification from before sirolimus, inception in patients with or without bronchiolitis obliterans syndrome. There were seven infections. One patient died of complications related to bronchiolitis obliterans.

CONCLUSION

Sirolimus was a useful alternative immunosuppressant, allowing significant tacrolimus withdrawal in transplant recipients with renal impairment. Sirolimus administration allowed recovery of renal function with low morbidity; it was useful for rescue of chronic renal impairment after lung transplantation.

Validation of Creatinine-Based Estimates of GFR When Evaluating Risk Factors in Longitudinal Studies of Kidney Disease

Whereas much research has investigated equations for obtaining estimated GFR (eGFR) from serum creatinine in cross-sectional settings, little attention has been given to validating these equations as outcomes in longitudinal studies of chronic kidney disease. A common objective of chronic kidney disease studies is to identify risk factors for progression, characterized by slope (rate of change over time) or time to event (time until a designated decline in kidney function or ESRD). The relationships of 35 baseline factors with eGFR-based outcomes were compared with the relationships of the same factors with iothalamate GFR (iGFR)-based outcomes in the African American Study of Kidney Disease and Hypertension (AASK; n = 1094). With the use of the AASK equation to calculate eGFR, results were compared between time to halving of eGFR or ESRD and time to halving of iGFR or ESRD (with effect sizes expressed per 1 SD) and between eGFR and iGFR slopes starting 3 mo after randomization. The effects of the baseline factors were similar between the eGFR- and iGFR-based time-to-event outcomes (Pearson R = 0.99, concordance R = 0.98). Small but statistically significant differences (P < 0.05, without adjustment for multiple analyses) were observed for seven of the 35 factors. Agreement between eGFR and iGFR was somewhat weaker, although still relatively high for slope-based outcomes (Pearson R = 0.93, concordance R = 0.92). Effects of covariate adjustment for age, gender, baseline GFR, and urine proteinuria also were similar between the eGFR and iGFR outcomes. Sensitivity analyses including death in the composite time-to-event outcomes or using the Modification of Diet in Renal Disease equation instead of the AASK equation provided similar results. In conclusion, the data from the AASK provide tentative support for use of outcomes that are based on an established eGFR formula using serum creatinine as a surrogate for measured iGFR-based outcomes in analyses of risk factors for the progression of kidney disease.

Predictors of chronic kidney disease in long-term survivors of lung and heart-lung transplantation

Renal insufficiency is common after non-renal organ transplants. The predictors of long-term renal outcomes are not well established. A total of 219 lung and heart-lung transplant recipients surviving more than 6 months after transplantation were studied to determine predictors of time to doubling of serum creatinine and end-stage kidney disease (ESKD) with death as a competing risk. Median follow-up was 79 months (range 9-222 months). Baseline estimated glomerular filtration rate (GFR) was 96.3+/-34.5 mL/min/1.73 m2. One hundred twenty-two recipients (55%) doubled their serum creatinine, 16 (7.3%) progressed to ESKD and 143 (65%) died. The majority of recipients who survived >6 years had a GFR<60 mL/min at both 1 and 7 years. Most of the loss of renal function occurred in the first year post-transplant. Older age at transplant, lower GFR at 1 month and cyclosporine use in the first 6 months predicted shorter time to doubling of serum creatinine when death was handled as a competing risk. Based on this prevalence data and using GFR decay and death as study endpoints, we offer sample size estimates for a prospective, interventional trial that is aimed at slowing or preventing the progression of kidney disease.

Chronic kidney disease in solid-organ transplantation

As the long-term survival of nonrenal solid-organ transplant recipients continues to improve, more complications related to transplantation occur. Among the most serious is chronic kidney disease (CKD). Although CKD was previously thought to only clinically affect a minority of this population, closer measurements of kidney function and monitoring of CKD complications now show that CKD will affect a significant number, if not a majority, of transplant recipients-particularly the long-term survivors who often have excellent function of their primary allograft. This article will review the incidence, risk factors, treatment, and outcomes of patients who develop CKD after heart, liver, and lung transplantation.

Progressive chronic kidney disease after pediatric lung transplantation

The development of chronic kidney disease (CKD) was evaluated in a large cohort of pediatric lung transplant recipients. Retrospective chart review identified 125 patients undergoing first lung transplant at St. Louis Children's Hospital and surviving 1 year. Mean age at transplant was 10.3 +/- 0.55 years, while mean time after transplant was 4.9 years. Serum creatinine nearly doubled from baseline 0.48 mg/dL +/- 0.02 (n = 125) to 0.87 mg/dL +/- 0.04 (n = 120) at 1 year, and tripled to 1.39 mg/dL +/- 0.15 (n = 23) by 7 years after transplant. The glomerular filtration rate (GFR), as estimated by the Schwartz formula, decreased from baseline 163 +/- 5.9 mL/min/1.73 m(2) (n = 109) to 88 +/- 2.5 (n = 104), reaching 69 +/- 9.0 (n = 6) by 10 years (p < 0.01). Seven patients developed end-stage kidney disease, and by 5 years after transplant, 38% of patients reached GFR < 60 mL/min. Older age at transplant and primary diagnosis of cystic fibrosis (CF) were both associated with decreased renal survival by Kaplan-Meier (KM) analysis. In summary, pediatric lung transplant recipients experience significant loss of renal function over time, as observed in other solid organ transplant recipients, and is most dramatic in adolescents.

Metabolic syndrome is associated with impaired long-term renal allograft function; not all component criteria contribute equally

Chronic renal transplant dysfunction (CRTD) remains a leading cause of renal allograft loss. Evidence suggests that immunological and ischemic insults are mainly associated with CRTD occurring within the first year after transplantation, whereas nonimmunological insults are predominantly associated with CRTD beyond the first year. Several cardiovascular risk factors, such as obesity, dyslipidemia, hypertension, and diabetes mellitus have been identified as important nonimmunological risk factors for CRTD. These risk factors constitute the metabolic syndrome (MS). As renal allograft function is a surrogate marker of renal allograft loss, we investigated the association of MS with impairment of renal allograft function beyond the first year after transplantation in a cross-sectional study of 606 renal transplant outpatients. Metabolic syndrome was defined using the definition of the National Cholesterol Education Program. Renal allograft function was assessed as the 24-h urinary creatinine clearance. A total of 383 out of 606 patients (63%) suffered from MS at a median time of 6 years (2.6-11.4) post-transplant. Presence of MS was associated with impaired renal allograft function beyond 1 year post-transplant [-4.1 mL/min, 95%CI (-7.1, -1.1)]. The impact of MS did not change appreciably after adjustment for established risk factors for CRTD [-3.1 mL/min, 95%CI (-6.0, -0.2)]. However, not all component criteria of MS contributed equally. Only systolic blood pressure and hypertriglyceridemia were independently associated with impaired renal allograft function beyond 1 year post-transplant in multivariate analyses.

Principles and Clinical Application of Assessing Alterations in Renal Elimination Pathways

Drugs and metabolites are eliminated from the body by metabolism and excretion. The kidney makes the major contribution to excretion of unchanged drug and also to excretion of metabolites. Net renal excretion is a combination of three processes - glomerular filtration, tubular secretion and tubular reabsorption. Renal function has traditionally been determined by measuring plasma creatinine and estimating creatinine clearance. However, estimated creatinine clearance measures only glomerular filtration with a small contribution from active secretion. There is accumulating evidence of poor correlation between estimated creatinine clearance and renal drug clearance in different clinical settings, challenging the 'intact nephron hypothesis' and suggesting that renal drug handling pathways may not decline in parallel. Furthermore, it is evident that renal drug handling is altered to a clinically significant extent in a number of disease states, necessitating dosage adjustment not just based on filtration. These observations suggest that a re-evaluation of markers of renal function is required. Methods that measure all renal handling pathways would allow informed dosage individualisation using an understanding of renal excretion pathways and patient characteristics. Methodologies have been described to determine individually each of the renal elimination pathways. However, their simultaneous assessment has only recently been investigated. A cocktail of markers to measure simultaneously the individual renal handling pathways have now been developed, and evaluated in healthy volunteers. This review outlines the different renal elimination pathways and the possible markers that can be used for their measurement. Diseases and other physiological conditions causing altered renal drug elimination are presented, and the potential application of a cocktail of markers for the simultaneous measurement of drug handling is evaluated. Further investigation of the effects of disease processes on renal drug handling should include people with HIV infection, transplant recipients (renal and liver) and people with rheumatoid arthritis. Furthermore, changes in renal function in the elderly, the effect of sex on renal function, assessment of living kidney donors prior to transplantation and the investigation of renal drug interactions would also be potential applications. Once renal drug handling pathways are characterised in a patient population, the implications for accurate dosage individualisation can be assessed. The simultaneous measurement of renal function elimination pathways of drugs and metabolites has the potential to assist in understanding how renal function changes with different disease states or physiological conditions. In addition, it will further our understanding of fundamental aspects of the renal elimination of drugs.

Predictors of renal function following lung or heart-lung transplantation

BACKGROUND

Renal failure is a common complication following non-renal solid organ transplantation. The purpose of our study was to define the rate of decline in renal function and to identify independent risk factors associated with renal failure following lung or heart-lung transplantation.

METHODS

Between May 1986 and December 1998, 219 patients underwent lung or heart-lung transplantation at the University of Minnesota and survived at least six months (33 heart-lung, 66 bilateral single lung, and 120 unilateral single lung transplants). The mean age at the time of transplant was 45.9 +/- 11.6 years (mean +/- SD; range, 15 to 65 years), and the mean pre-transplant serum creatinine level was 0.88 +/- 0.19 mg/dL. All patients were treated with a calcineurin inhibitor (164 cyclosporine, 55 tacrolimus).

RESULTS

During the follow-up period (median 44 months, range 6.8 to 163 months), 16 patients (7.3%) developed end-stage renal disease. The cumulative incidence of doubling of serum creatinine was 34% at one year, 43% at two years and 53% by five years. Factors associated with the primary end point of the time to doubling of the baseline serum creatinine by proportional hazards regression were cumulative periods with diastolic blood pressure greater than 90 mm Hg [relative risk (RR) 1.30, P = 0.02] and the serum creatinine value at one month post-transplantation (RR 1.28, P = 0.03). Use of tacrolimus during the first six months after transplantation was associated with a significant decrease in the risk for time to doubling of serum creatinine (RR 0.38, P = 0.009) and a lower rate of acute rejection.

CONCLUSIONS

These results suggest that potential renoprotective strategies following lung or heart-lung transplantation include avoidance of peri-transplant renal injury, diligent blood pressure control, and preferential use of tacrolimus over cyclosporine.

Medical Management Considerations for Patients With Lung Transplantation

Lung transplantation has become an accepted modality for the treatment of end-stage lung disease. Adult and pediatric patients with a variety of lung diseases, including cystic fibrosis, chronic obstructive pulmonary disease, and idiopathic pulmonary fibrosis are candidates for lung transplantation. Lung transplantation can extend survival and improve quality of life for these patients. With the introduction of new immunosuppressive agents and enhanced surgical and medical care, both short- and long-term morbidity and mortality in these populations, although not as good as other transplant types, are improving. After lung transplantation, recipients continue to face a number of obstacles including post-operative complications, complex drug regimens, drug-induced toxicities, infection, and rejection. An understanding of the management and monitoring issues after lung transplantation is the focus of this review.