SummaryBackground and objectives The burden of AKI around the globe has not been systematically examined.Design, setting, participants, & measurements A systematic review (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) of large cohort studies was conducted to estimate the world incidence of AKI and its stages of severity and associated mortality, and to describe geographic variations according to countries, regions, and their economies. AKI definitions were reclassified according to the Kidney Disease Improving Global Outcomes (KDIGO) staging system. Randomeffects model meta-analyses and meta-regressions were used to generate summary estimates and explore sources of heterogeneity.Results There were 312 studies identified (n=49,147,878) , primarily in hospital settings. Most studies originated from North America, Northern Europe, and Eastern Asia, from high-income countries, and from nations that spent $5% of the gross domestic product on total health expenditure. Among the 154 studies (n=3,585,911) that adopted a KDIGO-equivalent AKI definition, the pooled incidence rates of AKI were 21.6% in adults (95% confidence interval [95% CI], 19.3 to 24.1) and 33.7% in children (95% CI, 26.9 to 41.3). The pooled AKI-associated mortality rates were 23.9% in adults (95% CI, 22.1 to 25.7) and 13.8% in children (95% CI, 8.8 to 21.0). The AKIassociated mortality rate declined over time, and was inversely related to income of countries and percentage of gross domestic product spent on total health expenditure.Conclusions Using the KDIGO definition, 1 in 5 adults and 1 in 3 children worldwide experience AKI during a hospital episode of care. This analysis provides a platform to raise awareness of AKI with the public, government officials, and health care professionals.

Background Targeting higher hemoglobin with erythropoiesis-stimulating agents (ESAs) to treat anemia of chronic kidney disease (CKD) is associated with increased cardiovascular risk. Study Design Meta-regression analysis examining the association of ESA dose with adverse outcomes, independent of target or achieved hemoglobin. Setting and Population Patients with anemia of CKD, irrespective of dialysis status. Selection Criteria for Studies We searched MEDLINE (inception to August 2010) and bibliographies of published meta-analyses and selected randomized controlled trials assessing the efficacy of ESAs for treatment of anemia in adults with CKD, with minimum 3-month duration. Two authors independently screened citations and extracted relevant data. Individual study arms were treated as cohorts and constituted the unit of analysis. Predictors ESA dose standardized to a weekly epoetin alfa equivalent, and hemoglobin levels. Outcomes All-cause and cardiovascular mortality, cardiovascular events, kidney disease progression or transfusion requirement. Results 31 trials (12,956 patients) met criteria. All-cause mortality was associated with higher (per epoetin-alfa–equivalent 10,000-U/wk increment) first-3-month mean ESA dose (incidence rate ratio [IRR], 1.42; 95% CI, 1.10–1.83) and higher total-study-period mean ESA dose (IRR, 1.09; 95% CI, 1.02–1.18). First-3-month ESA dose remained significant after adjusting for first-3-month mean hemoglobin (IRR, 1.48; 95% CI, 1.02- 2.14), as did total-study-period mean ESA dose adjusting for target hemoglobin (IRR, 2 1.41; 95% CI, 1.08–1.82). Parameter estimates between ESA dose and cardiovascular mortality were similar in magnitude and direction but not statistically significant. Higher total-study-period mean ESA dose was also associated with increased rate of hypertension, stroke, and thrombotic events including dialysis vascular access-related thrombotic events. Limitations use of study-level aggregated data; use of epoetin alfa–equivalent doses; lack of adjustment for confounders. Conclusions In patients with CKD, higher ESA dose might be associated with all-cause mortality and cardiovascular complications independent of hemoglobin.

Background Increased left ventricular (LV) mass is a risk factor for cardiovascular mortality in patients with chronic kidney failure. More frequent or extended hemodialysis (HD) has been hypothesized to have a beneficial effect on LV mass. Study Design Meta-analysis. Setting & Population MEDLINE literature search (inception-April 2011), Cochrane Central Register of Controlled Trials and ClinicalTrials.gov using the search terms “short daily HD”, “daily HD”, “quotidian HD”, “frequent HD”, “intensive HD”, “nocturnal HD”, and “home HD”. Selection Criteria for Studies Single-arm cohort studies (with pre- and post-study evaluations) and randomized controlled trials examining the effect of frequent or extended HD on cardiac morphology and function, and blood pressure parameters. Studies of hemofiltration, hemodiafiltration and peritoneal dialysis were excluded. Intervention Frequent (2–8 hours,> thrice weekly) or extended (>4 hours, thrice weekly) HD as compared with conventional (≤ 4 hours, thrice weekly) HD. Outcomes Absolute changes in cardiac morphology and function, including LV mass index (LVMI) (primary), and blood pressure parameters (secondary). Results We identified 38 single-arm studies, 5 crossover trials and 3 randomized controlled trials. By meta-analysis of 23 study arms, frequent or extended HD significantly reduced LVMI from baseline (−31.2 g/m2, 95% CI, −39.8 to −22.5; P<0.001).The 3 randomized trials found a less pronounced net reduction in LVMI (−7.0 g/m2; 95% CI, −10.2 to −3.7; P<0.001). LV ejection fraction improved by 6.7% (95% CI, 1.6 to 11.9; P=0.01). Other cardiac morphological parameters displayed similar improvements. There were also significant decreases in systolic, diastolic, and mean blood pressure, and mean number of anti-hypertensive medications. Limitations Paucity of randomized controlled trials. Conclusions Conversion from conventional to frequent or extended HD is associated with an improvement in cardiac morphology and function, including LVMI and LV ejection fraction, respectively, and in several blood pressure parameters, which collectively might confer long-term cardiovascular benefit. Trials with long-term clinical outcomes are needed.