Proteinuria after kidney transplantation, relationship to allograft histology and survival

Proteinuria is associated with reduced kidney allograft survival. Herein we assessed the association between proteinuria, graft histology and survival. The cohort included 613 kidney allograft recipients who had proteinuria (measured) and surveillance biopsies at 1-year posttransplant. Proteinuria >150 mg/day was detected in 276 patients (45%) and in 182 of these, proteinuria was below 500. In >84% of patients even low levels of proteinuria were associated with albuminuria. Proteinuria was associated with the presence of graft glomerular pathology and the use of sirolimus. Eighty percent of patients with proteinuria >1500 mg/day had glomerular pathology on biopsy. However, lower levels of proteinuria were not associated with specific pathologies at 1 year. Compared to no sirolimus, sirolimus use was associated with higher prevalence of proteinuria (40% vs. 76%, p < 0.0001) and higher protein excretion (378 + 997 vs. 955 + 1986 mg/day, p < 0.0001). Proteinuria was associated with reduced graft survival (HR = 1.40, p = 0.001) independent of other risk factors including, glomerular pathology, graft function, recipient age and acute rejection. The predominant pathology in lost allografts (n = 57) was glomerular, particularly in patients with 1-year proteinuria >500. Thus, proteinuria, usually at low levels (<500 mg/day), is present in 45% of recipients at 1 year. However, and even low levels of proteinuria relate to poor graft survival. Proteinuria and glomerular pathology relate independently to survival.

Transplant glomerulopathy: subclinical incidence and association with alloantibody

Transplant glomerulopathy (TG) usually has been described as part of a constellation of late chronic histologic abnormalities associated with proteinuria and declining function. The current study used both protocol and clinically-indicated biopsies to investigate clinical and subclinical TG, their prognosis and possible association with alloantibody. We retrospectively studied 582 renal transplants with a negative pre-transplant T-cell complement dependent cytotoxicity crossmatch. TG was diagnosed in 55 patients, 27 (49%) based on protocol biopsy in well-functioning grafts. The cumulative incidence of TG increased over time to 20% at 5 years. The prognosis of subclinical TG was equally as poor as TG diagnosed with graft dysfunction, with progressive worsening of histopathologic changes and function. Although TG was associated with both acute and chronic histologic abnormalities, 14.5% of TG biopsies showed no interstitial fibrosis or tubular atrophy, while 58% (7/12) of biopsies with severe TG showed only minimal abnormalities. TG was associated with acute rejection, pretransplant hepatitis C antibody positivity and anti-HLA antibodies (especially anti-Class II), with the risk increasing if the antibodies were donor specific. We suggest that subclinical TG is an under-recognized cause of antibody-mediated, chronic renal allograft injury which may be mechanistically distinct from other causes of nephropathy.

Diurnal blood pressure changes one year after kidney transplantation: relationship to allograft function, histology, and resistive index

Loss of circadian BP change has been linked to target organ damage and accelerated kidney function loss in hypertensive patients with and without chronic kidney disease. Ambulatory BP-derived data from 119 consecutive kidney transplant recipients who presented for the first annual evaluation were examined in relation to allograft function, histology, and ultrasound findings. A total of 101 (85%) patients were receiving antihypertensive medications (median 2), and 85 (71%) achieved target awake average systolic BP (SBP) of <135 mmHg. A day-night change in SBP by 10% or more (dippers) was detected in 29 (24%). Dipping status was associated with younger recipient age, lack of diabetes, low chronic vascular score, and low resistive index. Nondippers and reverse dippers had lower GFR compared with dippers (P = 0.04). For every 10% nocturnal drop in SBP, GFR increased by 4.6 ml/min per 1.73 m(2) (R = 0.3, P = 0.003). Nondippers and reverse dippers were equally common in recipients with normal histology and in those with pathologic findings on surveillance biopsy. On multivariate analysis, percentage of nocturnal fall in SBP and elevated resistive index independently correlated with GFR. This study indicates that lack of nocturnal fall in SBP is related to poor allograft function, high chronic vascular score, and high resistive index irrespective of allograft fibrosis. Further studies are needed to determine whether restoration of normal BP pattern will confer better allograft outcome.

Polyomavirus-associated nephropathy risk in kidney transplants: the influence of recipient age and donor gender

Polyomavirus-associated nephropathy (PVAN) is a frequent cause of kidney transplant failure. We determined the risk factors for biopsy-proven PVAN among 1027 recent kidney transplant recipients by univariate and multivariate analyses. The rate of PVAN was determined over an univariate and multivariate analysis over an average of 30 months of follow-up of patients receiving predominantly living donor grafts with antibody induction and sequential surveillance biopsies to detect subclinical graft disease. Seventy-four transplant recipients were diagnosed with PVAN with the finding made on surveillance biopsy in 40 patients. These 40 cases did not differ from the 34 non-surveillance cases with respect to baseline clinical characteristics or initial histological features. Older recipient age and female donor gender were independent risks associated with PVAN. Factors not linked to PVAN risk included the use and type of induction agent, use of tacrolimus vs sirolimus, the number of human lympocyte antigen (HLA) mismatches, or the frequency of acute rejection. We conclude that PVAN preferentially affects older age patients and allografts from female donors but is unrelated to immunological risk, choice of immunosuppression, or rejection history.

Assessment of changes in kidney allograft function using creatinine-based estimates of glomerular filtration rate

These analyses assessed whether creatinine based estimates of glomerular filtration rate (eGFR) accurately represent (1) graft function at different times post-transplant and (2) changes in function over time. These analyses compared iothalamate GFR to eGFR in 684 kidney allograft recipients. Changes in graft function over time (GFR slope) were measured in 360 of 459 recipients (78%) who were followed for at least 3 years. Ninety-five percent of the patients were Caucasians and 72% received kidneys from living donors. All eGFR calculations correlated significantly with GFR at all time points. However, eGFR were less precise and less accurate during the first-year post-transplant than thereafter. The average rate of GFR change (slope) was -2.93 +/- 11.3%/year (-1.06 +/- 5.3 mL/min/1.73 m(2)/year). Fifty-four percent of patients had stable or positive GFR slopes. The GFR and eGFR slopes were highly correlated. However, eGFR slope, particularly when calculated by MDRD, significantly underestimated the number of patients with declining graft function. For example, 165 out of 360 patients (46%) lost GFR faster than -1 mL/min/1.73 m(2)/year. eMDRD identified only 83 of these patients (50%) while the eMayo formula identified 134 (81%). In conclusion, eGFR correlate with GFR but they have relatively low precision and accuracy particularly early post-transplant. eGFR slopes underestimate graft functional loss although some formulas are significantly better than others for this calculation.

Protocol biopsies in renal transplantation: insights into patient management and pathogenesis

A 1-day symposium on the application of protocol biopsies in renal transplantation was held in Boston, 21 July 2006. Representatives from centers with extensive experience in the use of protocol biopsies for routine patient care and research reported results on the pathological findings and their value in patient management. The consensus was that protocol biopsies, in experienced hands, are a safe and valuable means of detecting subclinical disease that can benefit from modification of therapy. Furthermore, molecular studies reveal evidence of activity or progression not readily appreciated by histological techniques. Wider application is expected in multicenter clinical trials to predict and validate outcomes. The principal barrier to wider use of protocol biopsies is knowledge of the benefits of intervention.

Comparison of Low Versus High Tacrolimus Levels in Kidney Transplantation: Assessment of Efficacy by Protocol Biopsies

BACKGROUND

The use of calcineurin inhibitors is generally guided by drug blood levels. However, those levels are chosen based on clinical experience, lacking adequate titration studies.

METHODS

In these analyses, we compared clinical and histologic endpoints in two groups of kidney transplant recipients: in the first (HiTAC, January 2000 to June 2002, n=245) tacrolimus levels were significantly higher than in the second (LoTAC, July 2002 to September 2004, n=330). This change in drug levels (15% reduction) was made in an attempt to reduce the incidence of polyoma virus nephropathy (PVAN). Other immunosuppressive medications were unchanged during these two time periods.

RESULTS

The recipient and donor demographics were not statistically different between the two groups. Compared to HiTAC, at one year posttransplant LoTAC had: 1) lower incidence of PVAN (10.5% vs. 2.5%, P<0.0001); 2) lower fasting glucose levels; 3) higher iothalamate glomerular filtration rate (52+/-19 vs. 59+/-17 ml/min/m, P<0.0001); and 4) on protocol one-year biopsies, lower incidence and severity of interstitial fibrosis (67% vs. 45%, P=0.003) and tubular atrophy (82% vs., 66%, P=0.01). The incidence and severity of acute rejection episodes was similar between both groups (7.8% versus 7.6%).

CONCLUSIONS

Modest reductions in tacrolimus exposure early posttransplant are associated with significant beneficial effects for the patient and the allograft without an increased immunologic risk.

Limitations of estimating glomerular filtration rate from serum creatinine in the general population

OBJECTIVE

To compare estimated glomerular filtration rate (GFR) in the general population on the basis of equations derived from different subsets of the general population.

PARTICIPANTS AND METHODS

Adults (ages _45 years) were randomly selected from 1997 to 2000 from the Olmsted County, Minnesota, population and had their serum creatinine levels measured. The GFR was estimated using previously reported equations derived from a sample of patients with chronic kidney disease (CKD), a sample of healthy persons, and the combined samples. Serum creatinine was measured with the same assay used to derive these equations.

RESULTS

Of 4203 subjects, 2042 (47% participation rate) were enrolled and studied. Serum samples from 1982 subjects were used to measure creatinine levels. The prevalence of a reduced estimated GFR (<60 mL/min per 1.73 m2) was 12% (95% confidence interval [CI], 10%-13%) based on an equation derived with all CKD patients, and this finding was similar to prior reports. However, the prevalence of a reduced estimated GFR was 5.7% (95% CI, 4.8%-6.8%) based on an equation derived with both CKD patients and healthy persons and 0.2% (95% CI, 0.1%-0.5%) based on an equation derived with all healthy persons. Women had a higher risk of reduced estimated GFR according to an equation derived with all CKD patients, but men had a higher risk with an equation derived with both CKD patients and healthy persons.

Glomerular volume and renal histology in obese and non-obese living kidney donors

The link between obesity and renal disease is unclear, and there is no consensus as to whether obese individuals are at increased risk for kidney disease after living kidney donation if they otherwise meet acceptance criteria. We retrospectively studied time-zero (implantation) biopsies in 49 obese (body mass index (BMI) > or = 30 kg/m2) and 41 non-obese (BMI < 30 kg/m2) renal donors that met acceptance criteria. We found that our obese donor population had higher systolic blood pressure (P < 0.001 vs non-obese) and higher absolute iothalamate clearance (P = 0.001 vs non-obese) before donation. The obese donors had larger glomerular planar surface area compared to non-obese controls (P = 0.017), and this parameter correlated with patient weight and urinary microalbumin excretion. Detailed examination of the biopsies revealed that although most histologic findings were similar between groups, the obese donors had more tubular dilation (P = 0.01), but less tubular vacuolization (P = 0.02) than the non-obese controls. There was also a trend toward more arterial hyalinosis in the obese patients than controls (P = 0.08). From these data, our studies detected subtle differences in donor organs obtained from obese compared to non-obese individuals. Further studies should be carried out to quantify the long-term impact of these findings.

Histologic findings one year after positive crossmatch or ABO blood group incompatible living donor kidney transplantation

Recent protocols have allowed successful positive crossmatch (+XM) and ABO incompatible (ABOI) kidney transplantation, although their long-term outcome is not clear. To begin to assess this issue we compared protocol biopsies performed 12 months posttransplant in 37 +XM, 24 ABOI and 198 conventional allografts. Although the majority in all three groups had only minimal histologic changes, transplant glomerulopathy (TG) was significantly increased in +XM (22% vs. 13% ABOI vs. 8% conventional, p = 0.015), and correlated with prior humoral rejection (HR) by multivariate analysis (odds ratio 17.5, p < or = 0.0001). Patients with a prior history of HR also had a significant increase in interstitial fibrosis (No HR 54% vs. HR 86%, p = 0.045). In the absence of HR no difference in histologic changes was seen between groups, although all three groups had a demonstrable mild increase in interstitial fibrosis from biopsies performed at the time of transplant. Thus, although HR is associated with an increase in TG, in its absence allograft histology is similar in +XM, ABOI and conventional allografts 1 year posttransplant.

Interpreting post-transplant proteinuria in patients with proteinuria pre-transplant

Increasing numbers of patients receive kidney transplants before initiation of dialysis or shortly thereafter. Some of these patients have significant proteinuria pre-transplant making the interpretation of post-transplant proteinuria problematic. In this study, we evaluated post-transplant proteinuria in 115 patients who had urine protein measured within 3 months of transplant and assessed the association of proteinuria with allograft pathology. Proteinuria declined rapidly from 3650 +/- 3702 mg/day pre-transplant to 550 + 918 at 3 weeks (p < 0.0001) and continued to decline until 1 year post-transplant (472 +/- 1116, p < 0.0001 vs. 3 weeks). Proteinuria greater than 3000 mg/day was present in 48 patients (42%) pre-transplant, in 1 patient (1%) at 3 weeks and in 4 patients (4%) at 1 year. Surveillance graft biopsies were done at 1 year in 93% of patients. Proteinuria > or = 1500 mg/day and/or an absolute increase in proteinuria > 500 mg/day after 3 weeks post-transplant was associated with allograft glomerular pathology. In conclusion, pre-transplant proteinuria, even when high grade, declines rapidly after transplantation. Failure to decline or persistence of proteinuria greater than 1500 mg/day is indicative of allograft pathology.

Complete avoidance of calcineurin inhibitors in renal transplantation: a randomized trial comparing sirolimus and tacrolimus

Calcineurin inhibitors have decreased acute rejection and improved early renal allograft survival, but their use has been implicated in the development of chronic nephrotoxicity. We performed a prospective, randomized trial in kidney transplantation comparing sirolimus-MMF-prednisone to tacrolimus-MMF-prednisone. Eighty-one patients in the sirolimus group and 84 patients in the tacrolimus group were enrolled (mean follow-up = 33 months; range 13-47 months). At 1 year, patient survival was similar in the groups (98% with sirolimus, 96% with tacrolimus; p = 0.42) as was graft survival (94% sirolimus vs. 92% tacrolimus, p = 0.95). The incidence of clinical acute rejection was 10% in the tacrolimus group and 13% in the sirolimus group (p = 0.58). There was no difference in mean GFR measured by iothalamate clearance between the tacrolimus and sirolimus groups at 1 year (61 +/- 19 mL/min vs. 63 +/- 18 mL/min, p = 0.57) or 2 years (61 +/- 17 mL/min vs. 61 +/- 19 mL/min, p = 0.84). At 1 year, chronicity using the Banff schema showed no difference in interstitial, tubular or glomerular changes, but fewer chronic vascular changes in the sirolimus group. This study shows that a CNI-free regimen using sirolimus-MMF-prednisone produces similar acute rejection rates, graft survival and renal function 1-2 years after transplantation compared to tacrolimus-MMF-prednisone.

Kidney transplant function and histological clearance of virus following diagnosis of polyomavirus-associated nephropathy (PVAN)

Polyomavirus-associated nephropathy (PVAN) is managed by reduced immunosuppression with or without antiviral therapy. Data from 55 patients with biopsy-proven PVAN were analyzed for adverse outcomes and influence of baseline variables and interventions. During 20+/-11 months follow-up, the frequencies of graft loss, major and any functional decline were 15%, 24% and 38%, respectively. Repeat biopsies were performed in 45 patients with persistent PVAN in 47%. Low-dose cidofovir, IVIG and cyclosporine conversion were used in 55%, 20% and 55% of patients. No single intervention was associated with improved outcome. Of the variables examined, only degree of interstitial fibrosis at diagnosis was associated with kidney function decline. In contrast, donor source, interstitial fibrosis, proportion of BKV positive tubules and plasma viral load at diagnosis were all associated with failure of histological viral clearance. This retrospective, nonrandomized analysis suggests that: (i) Graft loss within 2 years of PVAN diagnosis is now uncommon, but ongoing functional decline and persistent infection occur frequently. (ii) Low-dose cidofovir, IVIG and conversion to cyclosporine do not abrogate adverse outcomes following diagnosis. (iii) Fibrosis at the time of diagnosis predicts subsequent functional decline. Further elucidation of the natural history of PVAN and its response to individual interventions will require prospective clinical trials.

Complete avoidance of calcineurin inhibitors in renal transplantation: a randomized trial comparing sirolimus and tacrolimus

Calcineurin inhibitors have decreased acute rejection and improved early renal allograft survival, but their use has been implicated in the development of chronic nephrotoxicity. We performed a prospective, randomized trial in kidney transplantation comparing sirolimus-MMF-prednisone to tacrolimus-MMF-prednisone. Eighty-one patients in the sirolimus group and 84 patients in the tacrolimus group were enrolled (mean follow-up = 33 months; range 13-47 months). At 1 year, patient survival was similar in the groups (98% with sirolimus, 96% with tacrolimus; p = 0.42) as was graft survival (94% sirolimus vs. 92% tacrolimus, p = 0.95). The incidence of clinical acute rejection was 10% in the tacrolimus group and 13% in the sirolimus group (p = 0.58). There was no difference in mean GFR measured by iothalamate clearance between the tacrolimus and sirolimus groups at 1 year (61 +/- 19 mL/min vs. 63 +/- 18 mL/min, p = 0.57) or 2 years (61 +/- 17 mL/min vs. 61 +/- 19 mL/min, p = 0.84). At 1 year, chronicity using the Banff schema showed no difference in interstitial, tubular or glomerular changes, but fewer chronic vascular changes in the sirolimus group. This study shows that a CNI-free regimen using sirolimus-MMF-prednisone produces similar acute rejection rates, graft survival and renal function 1-2 years after transplantation compared to tacrolimus-MMF-prednisone.

Predicting subsequent decline in kidney allograft function from early surveillance biopsies

Identifying factors that are predictive of allograft loss might be an important step toward prolonging kidney allograft survival. In this study we sought to determine the association between histologic changes on 1-year surveillance biopsies, changes in graft function and survival. This analysis included 292 adults, recipients of kidneys from living donors (69%) or deceased donors (31%), transplanted between 1998 and 2001 and followed up for 46 +/- 14 months. The primary end point was death-censored graft loss or a >50% reduction in GFR beyond 1 year. One-year biopsies were classified as: (i) Normal (N = 87, 30%), (ii) inflammation (N = 6, 2%), (iii) fibrosis (N = 131, 45%), (iv) fibrosis and inflammation (N = 53, 18%) and (v) transplant glomerulopathy (N = 15, 5%). By multivariate Cox analysis, survival related to biopsy classification (HR = 4.2, p = 0.001), graft function (HR = 0.97, p = 0.001) and HLA mismatches (HR = 1.003, p = 0.004). Using normal histology as a reference, fibrosis and inflammation (HR = 8.5, p < 0.0001) and glomerulopathy (HR = 10, p < 0.0001) related to poorer survival but mild fibrosis alone did not. Importantly, the degree of inflammation associated with fibrosis generally did not qualify for the diagnosis of borderline rejection. In conclusion, inflammation and glomerulopathy 1 year post-transplant predict loss of graft function and graft failure independently of function and other variables.

Predicting subsequent decline in kidney allograft function from early surveillance biopsies

Identifying factors that are predictive of allograft loss might be an important step toward prolonging kidney allograft survival. In this study we sought to determine the association between histologic changes on 1-year surveillance biopsies, changes in graft function and survival. This analysis included 292 adults, recipients of kidneys from living donors (69%) or deceased donors (31%), transplanted between 1998 and 2001 and followed up for 46 +/- 14 months. The primary end point was death-censored graft loss or a >50% reduction in GFR beyond 1 year. One-year biopsies were classified as: (i) Normal (N = 87, 30%), (ii) inflammation (N = 6, 2%), (iii) fibrosis (N = 131, 45%), (iv) fibrosis and inflammation (N = 53, 18%) and (v) transplant glomerulopathy (N = 15, 5%). By multivariate Cox analysis, survival related to biopsy classification (HR = 4.2, p = 0.001), graft function (HR = 0.97, p = 0.001) and HLA mismatches (HR = 1.003, p = 0.004). Using normal histology as a reference, fibrosis and inflammation (HR = 8.5, p < 0.0001) and glomerulopathy (HR = 10, p < 0.0001) related to poorer survival but mild fibrosis alone did not. Importantly, the degree of inflammation associated with fibrosis generally did not qualify for the diagnosis of borderline rejection. In conclusion, inflammation and glomerulopathy 1 year post-transplant predict loss of graft function and graft failure independently of function and other variables.

Thin basement membrane nephropathy associated with other glomerular diseases

Many reports confirm that thin basement membrane nephropathy (TBMN) commonly occurs together with other glomerular diseases such as minimal change glomerulonephritis, diabetes, membranous nephropathy, immunoglobulin (Ig)A glomerulonephritis, and focal segmental glomerulosclerosis. We postulate 3 explanations for these observations. The association of minimal change glomerulonephritis with TBMN probably is artifactual whereas the association with diabetes and membranous glomerulonephritis probably is coincidental. However, the link between TBMN and IgA disease and focal segmental glomerulosclerosis may be pathogenetic. Clinical evidence indicates that the presence of an associated glomerulopathy significantly worsens the prognosis of TBMN. Thus, patients with TBMN and another glomerular lesion usually have more marked proteinuria, and are more likely to have hypertension and renal insufficiency. The frequency of another glomerulopathy in patients with TBMN means that all patients in whom TBMN is suspected but who have heavy proteinuria or renal insufficiency should undergo a renal biopsy examination. However, there is no evidence that TBMN alters the prognosis of another glomerulopathy, and, in particular, patients with TBMN and IgA disease do not have different clinical features or a worse prognosis than those with IgA disease alone.

New onset hyperglycemia and diabetes are associated with increased cardiovascular risk after kidney transplantation

BACKGROUND

Post-transplant diabetes (PTDM) is a common and serious complication of kidney transplantation. The implications of developing hyperglycemia of lesser severity are not well understood.

METHODS

In this study we used American Diabetes Association (ADA) criteria to assess the incidence of abnormal glycemia post-transplant, the variables that relate to this complication, and the relationship between hyperglycemia and cardiovascular (CV) disease. Included in the study were 490 kidney recipients, transplanted from 1998 to 2003, without a history of diabetes, and with a pretransplant fasting glucose <126 mg/dL.

RESULTS

Within one week post-transplant, 45% of recipients had impaired fasting glycemia (IFG, glucose 100-125 mg/dL), and 21% PTDM (glucose > or =126). One year post-transplant, 33% of patients had IFG, and 13% PTDM. Risk factors for hyperglycemia at one year included: older recipient, male gender, higher BMI, higher pretransplant glucose, and higher glucose one week post-transplant (all P < 0.002 by multivariable analyses). During a follow-up period of 40 +/- 14 months, 12% of recipients had CV events (cardiac, CVA, and/or peripheral). Increasing fasting glucose levels at one, four, and/or 12 months post-transplant were significantly related to CV events. Furthermore, these relationships were independent of other CV risk factors, including: older age, CV events pretransplant, male gender, dyslipidemia, and transplant year. Fasting glucose levels >100 mg/dL were associated with higher incidence of post-transplant cardiac (P= 0.001) and peripheral vascular disease events (P= 0.003).

CONCLUSION

The incidence of post-transplant hyperglycemia and its CV impact have been underestimated. Pretransplant characteristics and, particularly, the glycemia during the first month post-transplant identified patients at risk of PTDM. Increasing glucose levels greater than 100 mg/dL, any time after the first month post-transplant, are associated with increasing CV risk. We postulate that aggressive detection and treatment of post-transplant hyperglycemia may significantly reduce CV morbidity and mortality after kidney transplantation.

Living donor kidney and autologous stem cell transplantation for primary systemic amyloidosis (AL) with predominant renal involvement

Primary systemic amyloidosis (AL) is characterized by multiorgan deposition of monoclonal immunoglobulin light chain. Renal involvement is common and impaired kidney function is associated with reduced median survival. Autologous stem cell transplantation (SCT) for AL achieves superior response rates compared to chemotherapy alone but patients with end-stage renal disease (ESRD) may be excluded from consideration. A treatment approach consisting of living donor kidney transplantation (LDKTx) followed by autologous SCT was developed for AL with ESRD. Eight patients underwent LDKTx with immediate graft function. Two suffered unanticipated complications post-KTx and died 10 and 3 months later. Two cases of subclinical acute cellular rejection (ACR) and one case of clinical ACR occurred--all reversible with corticosteroid. Six patients had successful stem cell harvests performed and five of these underwent SCT with satisfactory trilineage engraftment. Renal function remained stable following SCT in four and was reduced in one due to infectious and bleeding complications. One patient, who has thus far elected not to undergo SCT, has proteinuria and histologic evidence of recurrent renal amyloidosis. This experience supports the feasibility of sequential living donor KTx and autologous SCT for carefully selected patients with ESRD due to AL.

Obesity in living kidney donors: clinical characteristics and outcomes in the era of laparoscopic donor nephrectomy

Acceptance of obese individuals as living kidney donors is controversial related to possible increased risk for surgical complications and concern that obesity may contribute to long-term renal disease. We retrospectively examined 553 consecutive hand-assisted laparoscopic living kidney donations between October 1, 1999 and April 1, 2003. We stratified donors into quartiles by baseline body mass index (BMI) assessing perioperative complications and 6-12 months post-donation metabolic and renal function. Compared to BMI <25 kg/m(2), high BMI donors (> or =35 kg/m(2)) had slightly longer operative times (mean increase 19 min), more overall perioperative complications (mostly minor wound complications), yet the same low rate of major surgical complications (conversion to open and re-operation) and similar length-of-stay (2.3 vs. 2.4 days). At 6-12 months after donation (mean 11 months), renal function and microalbuminuria did not differ with BMI. These results suggest that laparoscopic donor nephrectomy is generally safe in selected obese donors and does not result in a high rate of major perioperative complications. Obese donors have higher baseline cardiovascular risk and warrant risk reduction for long-term health. While early results are encouraging, we advocate careful study of obese donors and do not support their widespread use until longer follow-up is available.

Kidney allograft fibrosis and atrophy early after living donor transplantation

Kidney allograft failure is most often caused by chronic allograft nephropathy, a process of interstitial fibrosis (GIF) and tubular atrophy (TA). We assessed the pathology of living donor (LD) grafts compared to deceased donor (DD). Included are 321 recipients (245 LD; 76 DD) with protocol biopsies the first 2 years of transplant. In LD, GIF was present in 7%, 31%, 61% and 71% of grafts at 0, 4, 12 and 24 months. TA progressed in parallel to GIF. Compared to LD, more DD grafts had GIF at time 0 (29%, p = 0.002); thereafter the incidence of GIF was similar. In LD, GIF was associated with lower glomerular filtration rate (GFR)(1 year) (no GIF, 62 +/- 16; GIF, 49 +/- 15 mL/min/m(2) iothalamate clearance, p = 0.001) and reduced graft survival (HR = 2.2, p = 0.009). GIF in LD related to acute rejection (HR = 2.6, p = 0.01), polyoma nephropathy (OR = 4.4, p = 0.02) and lower levels of GFR 3 weeks post-transplant (HR = 0.961; p = 0.03, multivariate). However, GIF also developed in 53% of recipients lacking these covariates. Thus, GIF/TA develops in the majority of LD grafts, it is often mild but is associated with reduced function and survival. GIF frequently develops in the absence of risk factors. Lower GFR post-transplant identify patients at highest risk of GIF.

Transplantation in the diabetic patient with advanced chronic kidney disease: a task force report

On May 7 to 8, 2003, more than 60 physicians, surgeons, nurses, and allied health professionals met in Chicago, IL, to discuss state-of-the-art approaches to transplantation in the clinical management of patients with diabetes and advanced chronic kidney disease. Four work groups addressed pretransplantation evaluation and management, therapeutic alternatives for treatment of patients with chronic kidney disease, posttransplantation diabetes mellitus, and improving long-term kidney transplant outcomes in patients with diabetes. This report summarizes the deliberations and recommendations of the task force.

Using serum creatinine to estimate glomerular filtration rate: accuracy in good health and in chronic kidney disease

BACKGROUND

The National Kidney Foundation has advocated the use of the abbreviated Modification of Diet in Renal Disease (MDRD) equation to estimate glomerular filtration rate (GFR) from serum creatinine measurements in clinical laboratories. However, healthy persons were not included in the development of the MDRD equation.

OBJECTIVES

To assess the accuracy of the MDRD equation in patients with chronic kidney disease compared with healthy persons and to develop a new equation that uses both patients with chronic kidney disease and healthy persons.

DESIGN

Cross-sectional study.

SETTING

The Mayo Clinic, a tertiary-care medical center.

PARTICIPANTS

Consecutive patients (n = 320) who had an iothalamate clearance test specifically for chronic kidney disease evaluation and consecutive healthy persons (n = 580) who had an iothalamate clearance test specifically for kidney donor evaluation.

MEASUREMENTS

Serum creatinine levels, GFR, demographic characteristics, and clinical characteristics were abstracted from the medical record.

RESULTS

The MDRD equation underestimated GFR by 6.2% in patients with chronic kidney disease and by 29% in healthy persons. Re-estimated coefficients for serum creatinine and sex were similar to the original MDRD equation in the chronic kidney disease series but not in the healthy series. At the same serum creatinine level, age, and sex, GFR was on average 26% higher in healthy persons than in patients with chronic kidney disease (P < 0.001). A quadratic GFR equation was developed to estimate logarithmic GFR from the following covariates: 1/SCr, 1/SCr2, age, and sex (where SCr = serum creatinine).

LIMITATIONS

The new equation was not developed in a general population sample. Elderly and African-American persons were underrepresented.

CONCLUSION

The MDRD equation systematically underestimates GFR in healthy persons. A new equation developed with patients who have chronic kidney disease and healthy persons may be a step toward accurately estimating GFR when the diagnosis of chronic kidney disease is unknown.

Patient and graft outcomes from older living kidney donors are similar to those from younger donors despite lower GFR

BACKGROUND

Donor age adversely affects deceased-donor kidney transplant outcomes, but its influence on living-donor transplantation is less well characterized.

METHODS

Living-donor kidney transplants at a single center between 1998 and 2000 were reviewed. Data were abstracted for 52 transplants from donors aged > or =50 years and for a matched group of 104 transplants from donors aged <50 years. Survival indices were compared during the first three years' post-transplantation. Functional indices, including serial iothalamate clearances, were compared at 1, 12, and 24 months.

RESULTS

Predonation glomerular filtration rate (GFR) was lower among older donors (94 +/- 12 vs. 108 +/- 17 mL/min/SA) but post-transplant compensatory hypertrophy was similar (11.7 +/- 26.3% vs. 7.7 +/- 31.4%). Recipients of older-donor grafts were older (52.8 +/- 16.5 vs. 46.1 +/- 15.1 years) and more frequently unrelated to the donor (54% vs. 39%). Trends toward higher frequency of slow graft function, cytomegalovirus (CMV) infection, and polyomavirus nephropathy were observed for older-donor grafts. Three-year recipient, graft, and death-censored graft survivals were > or =90% for both groups. At 1, 12, and 24 months, serum creatinine was higher and GFR was lower among recipients of older- compared with younger-donor grafts. Other functional indices (urine total protein, serum potassium and uric acid, hemoglobin, and number of antihypertensives) were not different. Donor age correlated with graft GFR at 1, 12, and 24 months for the entire study cohort by linear regression.

CONCLUSION

Older donor age does not preclude excellent results from living-donor kidney transplantation but should be appreciated as being associated with relatively lower GFR.