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Background Chronic kidney disease (CKD) affects 10–13% of the population worldwide. CKD classification stratifies patients in five stages of risk for progressive renal disease based on estimated glomerular filtration rate (eGFR) by formulas and albuminuria. However, the reliability of formulas to reflect real renal function is a matter of debate. The effect of the error of formulas in the CKD classification is unclear, particularly for cystatin C–based equations. Methods We evaluated the reliability of a large number of cystatin C and/or creatinine-based formulas in the definition of the stages of CKD in 882 subjects with different clinical situations over a wide range of glomerular filtration rates (GFRs) (4.2–173.7 mL/min). Results Misclassification was a constant for all 61 formulas evaluated and averaged 50% for creatinine-based and 35% for cystatin C–based equations. Most of the cases were misclassified as one stage higher or lower. However, in 10% of the subjects, one stage was skipped and patients were classified two stages above or below their real stage. No clinically relevant improvement was observed with cystatin C–based formulas compared with those based on creatinine. Conclusions The error in the classification of CKD stages by formulas was extremely common. Our study questions the reliability of both cystatin C and creatinine-based formulas to correctly classify CKD stages. Thus the correct classification of CKD stages based on estimated GFR is a matter of chance. This is a strong limitation in evaluating the severity of renal disease, the risk for progression and the evolution of renal dysfunction over time. [ABSTRACT FROM AUTHOR]

Introduction: Plasmapheresis (PP) is a therapeutic apheresis technique used in the treatment of various renal and systemic diseases with varying degrees of proven clinical efficacy., Objective: To review our experience with PP at the Hospital Universitario de Canarias, focused on effectiveness and safety results in different disease groups., Material and Methods: A retrospective-descriptive study of patients treated with PP from 01/01/2006 to 31/12/2009 at the hospital. We analysed medical histories and demographic data (sex, age), biochemical parameters, underlying disease, volume and type of replacement used in the PP sessions (5% human albumin and/or fresh frozen plasma), complications with the technique, delay in starting PP treatment after suspected clinical diagnosis, number of PP sessions received, patient mortality, degree of renal impairment and evolution of renal function., Results: There were 51 patients studied, aged 50±18 years, of whom 60% were male; 331 PP sessions were performed. The diseases treated were grouped as: 11 vasculitis, 15 transplant immune activation, 5 haemolytic-uraemic syndrome (HUS), 7 idiopathic or thrombotic thrombocytopaenic purpura, 2 foetal Rh immunisations, 2 haematological diseases, 4 neurological diseases, among others. Overall mortality was 19.6% (n=10): 6 cases secondary to septic shock and the rest as a result of the evolution of the underlying disease, with 1 due to haemorrhagic shock in the renal biopsy area. There were no deaths in the transplant immune activation group. In the vasculitis group, there were 3 deaths (2 secondary to septic shock). Of the 10 patients who died, 9 did so within the first three months after diagnosis. Of the 26 renal biopsies performed, the most frequent indications were: vasculitis (23%), humoral rejection (42%), humoral rejection with calcineurin-inhibitor toxicity (12%) and HUS (8%), among others. Haemodialysis (HD) was required by 24 patients at the start of clinical symptoms: 9 of the 11 patients with vasculitis, 4 of the 5 patients with HUS and 5 of the 15 patients with transplant immune activation. At the end of evolution, 14 of them remained on the HD programme: 5 of the 11 patients with vasculitis, 2 of the 15 transplant patients and 3 of the 5 HUS patients. Significantly, patients who developed end kiney disease (EKD) in the vasculitis group were older and had higher creatinine at the onset of the disease. The transplant patients were monitored for anti-HLA class I or II before and after PP; there was a mean decrease of antibody titres in all but one patient; with an average decrease of 51% to 31%. In general, the PP technique was virtually free of complications. There were only 5 (3%) mild-moderate reactions to fresh plasma (perioral tingling and urticarial reactions) requiring pre-medication with steroids, but which did not lead to discontinuation of the treatment., Conclusion: Taking into account the wide variety of diseases that can benefit from PP and the nature of some of them, publishing our experience with this therapeutic method is of great importance. By increasing the description of case series by centre, we can add survival and renal function evidence in many uncommon diseases. Our study provides useful information for clinical practice and has also led us to reflect on future strategies to optimise outcomes in our patients.