Acute kidney injury following primary hip and knee arthroplasty surgery.

Acute kidney injury (AKI) is a recognised postoperative complication following primary hip/knee arthroplasty surgery. The aim of this study was to determine causative and potentially modifiable risk factors associated with postoperative AKI. Standard data were collected for 413 consecutive arthroplasty patients, both retrospectively and prospectively. Univariate and multivariate analyses were performed to identify any potential causative factors. Eight percent of patients developed postoperative AKI. Univariate analysis found increasing age, history of previous chronic kidney disease and requirement for postoperative intravenous fluids to be risk factors for AKI. The multivariate regression analysis model identified age and volume of postoperative fluid prescription as predictive of postoperative AKI. Antibiotic regime and prescription of non-steroidal anti-inflammatory drugs had no significant effect on the risk of AKI. No patients required dialysis but length of stay increased by 50% in the AKI group. Postoperative AKI may result in significant postoperative morbidity and increased length of stay, and may necessitate invasive therapies such as dialysis. Episodes of AKI could also predispose to future similar episodes and are associated with a long-term decrease in baseline renal function. This study has demonstrated that the identified risk factors are generally non-modifiable. Further work is suggested to determine whether targeted interventions in high risk patients would reduce the incidence of AKI.

Chronic kidney disease prevalence and secular trends in a UK population: the impact of MDRD and CKD-EPI formulae.

INTRODUCTION: Most UK laboratories use the MDRD4 formula to estimate glomerular filtration rate (eGFR), but this may exaggerate chronic kidney disease (CKD) prevalence. In a large adult population, we examined the impact of the more accurate CKD-EPI formulae on prevalence estimates, and on secular trends in prevalence. METHODS: We extracted all serum creatinine (SCr) results for adults, processed in our laboratory during two 1-year periods (2004, 2009-10). To minimize the effect of acute illness, a patient's lowest SCr was used for each period. eGFR (traceable to isotope dilution mass spectrometry value) was calculated using the MDRD4 and CKD-EPI formulae. Prevalence estimates were compared, with sub-group analysis by age and sex. RESULTS: In 2004, 102 322 patients had SCr tested (35.4% of the adult population), rising to 123 121 (42.3%) in 2009-10. The proportion tested rose with age to 86% of 85- to 89-year olds. The prevalence of CKD stages 3-5 was lower with the CKD-EPI formulae than the MDRD4 formula. The CKD-EPI formulae reclassified 17 014 patients (5.8%) to milder stages of CKD, most commonly from eGFR 60-89 ml/min/1.73m(2) and CKD stage 3A, in women, and in those <70 years old. 5172 patients (1.8%), mostly elderly women, were reclassified to more severe stages of CKD. Between the two time periods, the prevalence of CKD stages 3-5 rose from 5.44% to 5.63% of the population using MDRD4, but was static at 4.94% with CKD-EPI. CONCLUSION: The CKD-EPI formulae, which are more accurate than the MDRD4 formula at higher GFR, reduced the estimated prevalence of CKD stages 3-5 by 0.5% in 2004 and 0.7% in 2009-10. The greatest reclassification was seen in CKD 3A, particularly amongst middle-aged females. The minor rise in CKD prevalence between 2004 and 2009-10 seen with the MDRD4 formula was not confirmed with the CKD-EPI formulae. The CKD-EPI formulae may reduce overdiagnosis of CKD, but further assessment in the elderly is required before widespread implementation.

Stratifying risk in chronic kidney disease: an observational study of UK guidelines for measuring total proteinuria and albuminuria.

BACKGROUND: Proteinuria predicts poor renal and cardiovascular outcomes. Some guidelines recommend measuring proteinuria using albumin:creatinine ratio (ACR), while others recommend total protein:creatinine ratio (TPCR). AIM: To compare renal outcomes and mortality in the populations identified by these different recommendations. DESIGN: Retrospective longitudinal cohort study. METHODS: Baseline ACR and TPCR measurements were obtained from 5586 patients with chronic kidney disease (CKD) attending a Scottish hospital nephrology clinic. The cohort was divided into three groups with concordant results by ACR and TPCR (no proteinuria; low proteinuria; significant proteinuria) and one group with discordant results (significant proteinuria with TPCR, but not ACR). Outcomes were assessed using Kaplan-Meier plots and Cox proportional hazards models. RESULTS: Median follow-up was 3.5 years [interquartile range (IQR) 2.1-6.0]; 844 (15%) died at 3.0 years (IQR 1.8-4.7) and 468 (8%) started renal replacement therapy (RRT) at 1.7 years (IQR 0.6-3.4). Proteinuria was associated with a substantially increased risk of RRT and death. Patients with significant proteinuria by TPCR, but not ACR (n = 231) had high renal risk, and the highest all-cause mortality (log-rank P < 0.001). With multivariate analysis the risk fell below those with significant proteinuria with concordant results by ACR and TPCR but remained considerably higher than those without significant proteinuria. CONCLUSION: Proteinuria screening with TPCR identifies an additional 16% of patients with significant proteinuria, not identified using ACR. This subgroup has high renal risk, and high risk of all-cause mortality and therefore warrant identification. Guideline recommendations on proteinuria screening in CKD should be reconsidered.

Chronic kidney disease: evolving strategies for detection and management of impaired renal function.

Nephrologists have long been concerned about late referral of patients with severe kidney disease, and resultant poor outcomes on dialysis. But there is an increasing realisation that mild to moderate chronic kidney disease is far more common than previously appreciated. Furthermore, the main consequence of chronic kidney disease is not progression to dialysis, but increased risk of cardiovascular disease. Chronic kidney disease is at least as common and important a risk factor for cardiovascular disease as diabetes mellitus. The MDRD formula is a well-validated formula to estimate glomerular filtration rate, which is now being widely implemented by clinical chemistry laboratories, and should increase the recognition of chronic kidney disease. The K/DOQI classification of chronic kidney disease has gained international acceptance and provides the structure to guide referral and management. This classification, and associated guidelines, also focus attention on areas where evidence is lacking, and which urgently require research. These current developments will substantially change and improve how chronic kidney disease is identified and managed.

Early graft function and patient survival following cadaveric renal transplantation.

BACKGROUND: The influence of events that occur early following renal transplantation such as delayed graft function (DGF) and acute rejection on long-term graft survival has been widely reported, but its association with patient survival has received less attention. METHODS: We studied 589 patients who received their first cadaveric transplants between 1984 and 1993, all of whom received cyclosporine-based immunosuppression and who had a median follow-up of seven years. The following factors were identified, and both univariate and multivariate analyses were used to determine their association with long-term patient and graft survival: age, sex, duration of pretransplant dialysis, primary renal disease, immediate graft function (IGF), DGF, primary nonfunction (PNF), acute rejection, and serum creatinine at 3, 6, and 12 months. RESULTS: Patients with PNF had a poorer survival than those with DGF and IGF (P = 0.01), but there was no difference in survival between DGF and IGF (P = 0.54). Good graft function (serum creatinine of less than 200 mumol/liter) at three months was predictive of better long-term patient survival (P = 0.03). Other factors associated with poor patient outcome were older age, diabetes, adult polycystic kidney disease, male gender, and acute rejection. Cardiovascular disease was the most common cause of death (51.8%). Good graft function at three months (P < 0.001) and an absence of rejection episodes (P = 0.01) were associated with better graft survival. CONCLUSION: Patients with poor levels of early graft function (but not DGF) and those with either acute rejection episodes or early graft loss are at an increased risk of early death. These high-risk groups should be targeted for interventional studies in an attempt to improve patient survival.

Treatment of postrenal transplant erythrocytosis. Long-term efficacy and safety of angiotensin-converting enzyme inhibitors.

Fifty-two patients with postrenal transplant erythrocytosis were treated with an angiotensin-converting enzyme inhibitor (lisinopril or enalapril) for a median of 13 months (range 0-44). A significant fall in haemoglobin of 1.8 +/- 1.6 g dl-1 (range - 0.8 to 6.6) occurred over the first 3 months (p < 0.0001). The haemoglobin then remained stable for as long as 3 years. Both enalapril and lisinopril were equally effective. Therapy was withdrawn in 16 patients (31%) because of decline in renal function (6), anaemia (5), hypotension (3), hyperkalaemia (1) or erectile impotence (1) - complications which were all reversible. Angiotensin-converting enzyme inhibitors in low dose are a safe and effective long-term therapy for postrenal transplant erythrocytosis.

Overview of immunosuppressive therapy in organ transplantation.

Immunosuppressive drugs have transformed organ transplantation from a hazardous experiment in the 1950s to a routine treatment in the 1990s. This article reviews current immunosuppressive drugs and the principles underlying their use. Newer agents on the horizon are also discussed.