Agreement between two routine methods of estimation of glomerular filtration rate in patients with advanced and terminal chronic renal failure.

BACKGROUND: Estimations of glomerular filtration rate (GFR) obtained either by the modification of diet in renal disease study equation (MDRD-GFR) or by classic 24-hour urine collection-based methods (mean of creatinine and urea clearance (Ccr-ur)) are considered to be equivalent in patients with chronic renal failure (CRF). However, the agreement between both methods has been insufficiently studied in patients during the most advanced stages of CRF. METHODS: We compared 615 estimations of GFR performed by both methods simultaneously in adult (> 18 years) patients with advanced (aCRF) (15 - 30 ml/min/1.73m2) and preterminal (tCRF) (< 15 ml/min/1.73m2) chronic renal failure. We also analyzed the influence of some relevant covariables (demographic characteristics, inflammatory and nutritional markers) with respect to the concordance between both methods. RESULTS: In aCRF, mean GFR were 19.7 +/- 5.5 (MDRD-GFR) and 19.3 +/- 3.7 ml/min/1.73m2 (Ccr-ur) (mean difference 0.4 ml/min/1.73m2, 95% confidence interval CI -0.3/1.1, p = 0.26), with an intraclass correlation coefficient of 0.46. In tCRF, mean GFR was 12.5 +/- 4.2 and 10.4 +/- 2.7 ml/min/1.73m2, respectively (mean difference 2.1 ml/min/1.73m2, 95% CI 1.7/2.4, p < 0.0005), with an intraclass correlation co-efficient of 0.43. Multivariate analysis identified lean body mass, body mass index, protein nitrogen appearance, proteinuria, gender, age, albumin (aCRF) and prealbumin (tCRF) as variables independently correlated with the difference MDRD-GFR minus Ccr-ur. Lean body mass was by far the strongest predictor of deviations between both methods, both in aCRF (R2 = 0.66, p < 0.0005) and tCRF (R2 = 0.49, p < 0.0005). CONCLUSIONS: MDRD-GFR and Ccr-ur show an acceptable agreement in advanced stages of chronic renal failure. However, MDRD-GFR produces estimations of GFR systematically higher than those given by the Ccr-ur method, in patients with tCRF. Moreover, this overestimation is particularly marked in some high risk subsets, including elderly patients and those presenting markers of a poor nutritional condition. Until this issue is further clarified, GFR should be estimated using Ccr-ur rather than MDRD-GFR in patients with tCRF, as also in older and malnourished patients with aCRF, as this may represent a more conservative and safer approach at the time of planning initiation of renal replacement therapy.

Evaluation of renal grafts in patients with lupus nephritis as cause of end-stage renal disease.

INTRODUCTION: Kidney transplantation is the best option in end-stage renal disease (ESRD). For many years patients affected with lupus nephritis have had poor graft results. However, this has been changing over recent years with the development of new immunosuppressive drugs and a better comprehension of the natural evolution of the entity. METHODS: We studied 20 patients with lupus nephritis who received 22 kidney grafts: 15 women and five men (n = 11) who were treated with cyclosporine or with tacrolimus (n = 11). Secondary immunosuppression included mycophenolate match (MMF) (n = 13) or azathioprine (n = 9). We analyzed human leukocyte antigen, cold ischemia time, acute tubular necrosis, creatinine, cholesterol, triglycerides, glucose, blood pressure, acute rejection episodes, immunosuppression, infections, disease recurrences, as well as graft and patient survival. RESULTS: After a mean cold ischemia time of 22 +/- 4 hours, nine patients displayed delayed graft function of an average duration 9 +/- 4 days. At 36 +/- 35 months nine grafts were lost: two due to acute rejection; five to chronic allograft nephropathy; and two to venous thrombosis. One patient died of hemorrhagic shock. There were five cytomegalovirus infections. Graft survival was dependent on the type of secondary immunosuppression, incidence of acute rejection episodes and occurrence of delayed graft function. CONCLUSIONS: We found no clinical recurrence of lupus nephritis after transplantation and a low incidence of complications, although there was a trend toward thrombosis. The presence of delayed graft function, episodes of acute rejection, and receiving azathioprine instead of MMF as secondary immunosuppression were associated with poorer graft survival.