This Month in AJKD

Article Outline

• Off-Pump Coronary Artery Bypass Surgery and Acute Kidney Injury
• Quality of Life and Depression in CKD
• Cerebrovascular Disease Incidence, Characteristics, and Outcomes in Patients Initiating Dialysis
• Anemia Management in Dialysis
• Potential Role of Soluble ST2 Protein in Idiopathic Nephrotic Syndrome Recurrence Following Kidney Transplantation

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Off-Pump Coronary Artery Bypass Surgery and Acute Kidney Injury 

See Nigwekar et al, pages 413-423; and Bainbridge and Martin, pages 395-398.

Acute kidney injury (AKI) after coronary artery bypass grafting (CABG) is associated with significant morbidity and mortality. Whether an off-pump technique can reduce post-CABG AKI is debatable. In this issue, Nigwekar et al perform a systematic review and meta-analysis of randomized controlled trials (RCTs) and observational studies comparing off-pump CABG (OPCAB) with conventional CABG (CAB). 22 studies (6 RCTs and 16 observational studies including 27,806 adult patients not on long-term renal replacement therapy [RRT]) met the inclusion criteria. The pooled effect from both study cohorts showed a significant reduction in overall AKI and AKI requiring RRT in the OPCAB group compared with the CAB group. In RCTs, overall AKI was significantly reduced in the OPCAB group; however, no statistically significant difference was noted in AKI requiring RRT (though sensitivity analysis restricted to good-quality studies revealed a significant reduction in AKI). In the observational cohort, both overall and AKI requiring RRT were significantly less in the OPCAB group. In a related editorial, Bainbridge and Martin discuss the rationale for off-pump bypass surgery, provide an overview of the evidence for improvement in a number of clinical outcomes, and discuss the clinical implications.

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Quality of Life and Depression in CKD 

See Hedayati et al, pages 424-432 and pages 433-439; and Watnick, pages 399-402.

In this issue, Hedayati and colleagues offer new insights in 2 articles on depression in non–dialysis-dependent patients with stage 2-5 CKD. In the article beginning on page 433, a diagnostic test study is conducted to investigate screening characteristics of 2 depression self-report scales (the Beck Depression Inventory [BDI] and the 16-item Quick Inventory of Depressive Symptomatology-Self Report [QIDS-SR₁₆]) compared to a gold-standard reference test (a structured Diagnostic and Statistical Manual of Mental Disorders [Fourth Edition, DSM-IV]–based interview). Of the 272 patients studied, 57 had major depression according to the reference test. The authors concluded that both the BDI and QIDS-SR₁₆ are effective screening tools. In the article beginning on page 424, Hedayati et al describe factors associated with major depression in individuals with CKD. They found the prevalence of a major depressive episode did not vary significantly across CKD stages, but was associated with diabetes mellitus, comorbid psychiatric illness, and history of drug or alcohol abuse. An editorial by Dr Watnick notes that these articles are a first step toward enabling treatment of depression in CKD patients, but that future studies must assess long-term outcomes and subsequent randomized controlled trials need to address the efficacy and tolerability of therapy as it pertains to CKD patients.

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Cerebrovascular Disease Incidence, Characteristics, and Outcomes in Patients Initiating Dialysis 

See Sozio et al, pages 468-477; and Seliger, pages 403-405.

Stroke is the third most common cause of cardiovascular disease death in patients on dialysis therapy; however, characteristics of cerebrovascular disease, including clinical subtypes and subsequent consequences, have not been well described. In this issue, Sozio et al examine the patterns and outcomes of acute stroke in an incident dialysis population using data from the prospective multi-center Choices for Healthy Outcomes in Caring for ESRD (CHOICE) cohort, in which 1,041 incident dialysis patients treated in 81 clinics were followed up for up to 9 years. There were 165 participants who experienced a total of 200 cerebrovascular events with an overall incidence of 4.9 events/100 person-years. Ischemic stroke was the most common cerebrovascular event (76%), with cardioembolism subtype accounting for 28% of ischemic strokes. There was substantial delay in the time from onset of symptoms to evaluation (median of 8.5 hours), with only 56% of patients successfully avoiding death, or nursing home or skilled nursing facility placement. In an editorial, Dr Seliger outlines the current state of evidence linking CKD and cerebrovascular diseases and discusses potential means for nephrologists to improve cerebrovascular outcomes in dialysis patients.

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Anemia Management in Dialysis 

See Servilla et al, pages 498-510; and Bradbury et al, pages 554-560.

Previous studies suggest that African American hemodialysis patients require higher doses of epoetin to achieve hemoglobin targets and also have better survival compared with white hemodialysis patients. In this issue, Servilla et al explore the interaction of race in the relationships between epoetin dose and hemoglobin concentration with outcome in a retrospective longitudinal cohort of 12,733 epoetin-exposed incident hemodialysis patients (African Americans, n = 4,801; white, n = 7,386) treated in Dialysis Clinic, Inc (DCI) facilities during 2000 to 2006. Their results showed that hemoglobin concentrations less than 10 g/dL in whites and less than 11 g/dL in African Americans were associated with increased mortality and hospitalization versus the referent hemoglobin level of 11 to 11.9 g/dL. Hemoglobin levels of 13 g/dL or greater in whites were associated with decreased noncardiovascular mortality. Risk of mortality and hospitalization increased among individuals receiving epoetin doses of 20,000 units per week while epoetin doses below 8,000 units per week were associated with less risk (referent group of 8,000 to 12,499 units per week). Use of higher doses of epoetin was associated with increased mortality at hemoglobin concentrations of 10 to 12.9 g/dL and with increased hospitalization at all hemoglobin concentrations of 10 g/dL or greater. Also in this issue, a narrative review by Bradbury et al addresses the inherent biases in observational studies of erythropoiesis-stimulating agent therapy in hemodialysis patients and critically appraises analytical methods that may help minimize bias in such studies, concluding that decreased epoetin responsiveness in sicker patients generates confounding by indication, and statistical methods to account for this bias are further complicated by the presence of time-dependent confounding.

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Potential Role of Soluble ST2 Protein in Idiopathic Nephrotic Syndrome Recurrence Following Kidney Transplantation 

See Bruneau et al, pages 522-532; and Savin and Sharma, pages 406-409.

Corticosteroid-resistant idiopathic nephrotic syndrome (INS) recurs rapidly after transplantation in 30% to 50% of transplant recipients, suggesting the presence of 1 or more circulating factors that alter the glomerular filtration barrier. In this issue, Bruneau et al investigated the possible role of soluble ST2 (sST2) protein, a marker of T helper type 2 (T_H2) cells and a factor predicted to be regulated by the transcription factor c-Maf, hypothesizing that involvement of sST2 protein would be consistent with the observation that both T_H2 cells and c-Maf appear to be activated during INS relapse. Patients with biopsy-proven corticosteroid-resistant INS who had undergone kidney transplantation between September 1983 and April 2007 (n = 71) were divided into 2 groups: Patients who developed INS recurrence after transplantation (n = 31) and patients in whom INS did not recur (n = 40). The authors reported that sST2 protein levels were significantly increased after transplantation in patients with INS recurrence compared both with patients in whom INS did not recur as well as a control group with no history of idiopathic nephrotic syndrome; however, patients with recurrence expressed a normal sST2 isoform, and the sST2 protein was unable to induce podocyte injury in vitro or trigger proteinuria in rats. An editorial by Savin and Sharma acknowledges that identification of the unique components of INS patients' plasma and the biological activity of these components may reveal essential clues to the mechanisms of focal-segmental glomerular sclerosis, which they hope will identify permeability factors and their actions and lead to treatment to reverse the functional changes in the glomerular capillary wall, arrest disease progression, and prevent post-transplant recurrence.

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