Anna T. Mathew

Is a pre-operative brain natriuretic peptide or N-terminal pro-B-type natriuretic peptide measurement an independent predictor of adverse cardiovascular outcomes within 30 days of noncardiac surgery? A systematic review and meta-analysis of observational studies.

OBJECTIVES We conducted a systematic review and meta-analysis to determine if pre-operative brain natriuretic peptide (BNP) (i.e., BNP or N-terminal pro-B-type natriuretic peptide [NT-proBNP]) is an independent predictor of 30-day adverse cardiovascular outcomes after noncardiac surgery. BACKGROUND Pre-operative clinical cardiac risk indices have only modest predictive power. BNP predicts adverse cardiovascular outcomes in a variety of nonsurgical settings and may similarly predict these outcomes in the perioperative setting. METHODS We employed 5 search strategies (e.g., searching bibliographic databases), and we included all studies that assessed the independent prognostic value of pre-operative BNP measurement as a predictor of cardiovascular complications after noncardiac surgery. We determined study eligibility and conducted data abstraction independently and in duplicate. We calculated a pooled odds ratio using a random effects model. RESULTS Nine studies met eligibility criteria, and included a total of 3,281 patients, among whom 314 experienced 1 or more perioperative cardiovascular complications. The average proportion of patients with elevated BNP was 24.8% (95% confidence interval [CI]: 20.1 to 30.4%; I(2) = 89%). All studies showed a statistically significant association between an elevated pre-operative BNP level and various cardiovascular outcomes (e.g., a composite of cardiac death and nonfatal myocardial infarction; atrial fibrillation). Data pooled from 7 studies demonstrated an odds ratio (OR) of 19.3 (95% CI: 8.5 to 43.7; I(2) = 58%). The pre-operative BNP measurement was an independent predictor of perioperative cardiovascular events among studies that only considered the outcomes of death, cardiovascular death, or myocardial infarction (OR: 44.2, 95% CI: 7.6 to 257.0, I(2) = 51.6%), and those that included other outcomes (OR: 14.7, 95% CI: 5.7 to 38.2, I(2) = 62.2%); the p value for interaction was 0.28. CONCLUSIONS These results suggest that an elevated pre-operative BNP or NT-proBNP measurement is a powerful, independent predictor of cardiovascular events in the first 30 days after noncardiac surgery.

Chronic kidney disease and postoperative mortality: A systematic review and meta-analysis

Whether renal dysfunction is an important factor in postoperative risk assessment has been difficult to prove. In an attempt to provide more compelling evidence, we conducted a systematic review comparing the risk of death and cardiac events in patients with and without chronic kidney disease who underwent elective noncardiac surgery. From electronic databases, web search engines, and bibliographies, 31 cohort studies were selected, evaluating postoperative outcomes in patients with chronic kidney disease. These patients had higher risks of postoperative death and cardiovascular events compared to those with preserved renal function. The pooled incidence of postoperative death was significantly less in those with preserved renal function than in those patients with chronic kidney disease. Meta-regression showed a graded relationship between disease severity and postoperative death. In adjusted analysis, chronic kidney disease had a similar strength of association with postoperative death as diabetes, stroke, and coronary disease. Our review identifies chronic kidney disease as an independent risk factor for postoperative death and cardiovascular events after elective, noncardiac surgery.

Residual Kidney Function Decline and Mortality in Incident Hemodialysis Patients

In patients with ESRD, residual kidney function (RKF) contributes to achievement of adequate solute clearance. However, few studies have examined RKF in patients on hemodialysis. In a longitudinal cohort of 6538 patients who started maintenance hemodialysis over a 4-year period (January 2007 through December 2010) and had available renal urea clearance (CLurea) data at baseline and 1 year after hemodialysis initiation, we examined the association of annual change in renal CLurea rate with subsequent survival. The median (interquartile range) baseline value and mean±SD annual change of CLurea were 3.3 (1.9-5.0) and -1.1±2.8 ml/min per 1.73 m2, respectively. Greater CLurea rate 1 year after hemodialysis initiation associated with better survival. Furthermore, we found a gradient association between loss of RKF and all-cause mortality: changes in CLurea rate of -6.0 and +3.0 ml/min per 1.73 m2 per year associated with case mix-adjusted hazard ratios (95% confidence intervals) of 2.00 (1.55 to 2.59) and 0. 61 (0.50 to 0.74), respectively (reference: -1.5 ml/min per 1.73 m2 per year). These associations remained robust against adjustment for laboratory variables and ultrafiltration rate and were consistent across strata of baseline CLurea, age, sex, race, diabetes status, presence of congestive heart failure, and hemoglobin, serum albumin, and serum phosphorus levels. Sensitivity analyses using urine volume as another index of RKF yielded consistent associations. In conclusion, RKF decline during the first year of dialysis has a graded association with all-cause mortality among incident hemodialysis patients. The clinical benefits of RKF preservation strategies on mortality should be determined.

Optimal Method of Coronary Revascularization in Patients Receiving Dialysis: Systematic Review

BACKGROUND AND OBJECTIVES Patients receiving dialysis have a high burden of cardiovascular disease. Some receive coronary artery revascularization but the optimal method is controversial. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS The authors reviewed any randomized controlled trial or cohort study of 10 or more patients receiving maintenance dialysis which compared coronary artery bypass graft (CABG) to percutaneous intervention (PCI) for revascularization of the coronary arteries. The primary outcomes were short-term (30 d or in-hospital) and long-term (at least 1 year) mortality. RESULTS Seventeen studies were found. There were no randomized trials: all were retrospective cohort studies from years 1977 to 2002. There were some baseline differences between the groups receiving CABG compared with those receiving PCI, and most studies did not consider results adjusted for such characteristics. Given the variability among studies and their methodological limitations, few definitive conclusions about the optimal method of revascularization could be drawn. In an exploratory meta-analysis, short-term mortality was higher after CABG compared to PCI. A substantial number of patients died over a subsequent 1 to 5 yr, with no difference in mortality after CABG compared to PCI. CONCLUSIONS Although decisions about the optimal method of coronary artery revascularization in dialysis patients are undertaken routinely, it was surprising to see how few data has been published in this regard. Additional research will help inform physician and patient decisions about coronary artery revascularization.

Iron toxicity: relevance for dialysis patients

Iron deficiency is common among patients with advanced kidney disease, particularly those requiring hemodialysis. Intravenous iron is a convenient treatment to supplement iron and is widely used among hemodialysis patients. Its efficacy is well established that, with treatment, hemoglobin levels rise and erythropoiesis-stimulating agent dose requirements are reduced. However, the safety of intravenous iron with respect to patient-centered outcomes has not been adequately studied. A variety of studies have indicated potential safety concerns, but most have been of small numbers of patients and with end points studied that have unclear clinical relevance. In this study, issues related to iron toxicity are reviewed.

Increased bone fractures among elderly United States hemodialysis patients

BACKGROUND Fractures are an important cause of morbidity in hemodialysis patients. Multiple advances in the treatment of mineral and bone disease in hemodialysis patients have occurred. The purpose of this study was to determine whether the rate of fractures in hemodialysis patients has changed over time. METHODS We studied US Renal Data System (USRDS) datasets to determine the rates of hospitalized fractures among hemodialysis patients. The primary outcome was incidence of fractures requiring hospitalization. The fracture rate per 1000 person-years was calculated by year from 1992 to 2009. The first 90 days after initiating dialysis were excluded from analysis. RESULTS The incidence of hip and vertebral fractures increased from 12.5 fractures per 1000 patient-years in 1992 to 25.3 per 1000 patient-years in 2004 (P < 0.0001). Arm and leg fractures increased from 3.2 per 1000 patient-years in 1992 to 7.7 per 1000 patient-years in 2009 (P < 0.0001). The greatest increase in hip and verterbral fracture rate was seen in white patients >65 years of age. After 2004, the incidence rate of these fractures stabilized and subtly declined, but did not decrease significantly. CONCLUSIONS Fracture rates increased significantly in hemodialysis patients from 1992 to 2004, with most of the increase occurring in elderly white patients. Assessment of fracture risk and management in dialysis patients at greatest risk requires greater emphasis and further study.

Challenges and opportunities in late-stage chronic kidney disease

There is increasing recognition that chronic diseases are a major challenge for health delivery systems and treasuries. These are highly prevalent and costly diseases and frequency is expected to increase greatly as the population of many countries ages. Chronic kidney disease (CKD) has not received the same attention as other chronic diseases such as congestive heart failure; yet, the prevalence and costs of CKD are substantial. Greater recognition and support for CKD may require that the disease no longer be viewed as one continuous disease state. Early CKD stages require less complex care and generate lower costs. In contrast, late-stage CKD is every bit as complex and costly as other major chronic diseases. Health authorities may not recognize and fund CKD care appropriately until late-stage CKD is defined clearly as separate and distinct from earlier stages of disease. In this review, we describe the burden of chronic diseases, consider the challenges and barriers and propose processes to improve late-stage CKD care. In particular, we recommend the need for improved continuity of care, enhanced use of information technology, multidisciplinary care, timely referral to nephrologists, protocol use and improved patient engagement.

Reducing hospital readmissions in patients with end-stage kidney disease.

ESKD patients have a large burden of disease, with high rates of readmission to hospital compared with the general population. A readmission after an acute index hospital discharge is either planned or unplanned. A proportion of unplanned readmissions are potentially avoidable, and could have been prevented with optimized transitional care. Readmissions pose financial cost to the health care system and emotional cost to patients and caregivers. In other chronic diseases with high readmission risk, such as congestive heart failure, interventions have improved transitional care and reduced readmission risk. In reviewing the existing literature on readmissions in ESKD, the definition and risk of readmission varied widely by study, with many potentially associated factors including comorbid diseases such as anemia and hypoalbuminemia. An ESKD patients requisite follow-up in the outpatient dialysis facility provides an opportunity to improve transitional care at the time of discharge. Despite this, our review of existing literature found no studies which have tested interventions to reduce the risk of readmission in ESKD patients. We propose a framework to define the determinants of avoidable readmission in ESKD, and use this framework to define a research agenda. Avoidable readmissions in ESKD patients is a topic prime for in-depth study, given the high-risk nature in this patient population, financial and societal costs, and potential for risk modification through targeted interventions.

Increasing Hip Fractures in Patients Receiving Hemodialysis and Peritoneal Dialysis

Background/Aims: Dialysis patients are at increased risk for hip fractures. Because changes in treatment of metabolic bone disease in this population may have impacted bone fragility, this study aims to analyze the longitudinal risk for fractures in hemodialysis (HD) and peritoneal dialysis (PD) patients. Methods: Using the United States Renal Data System database from 1992 to 2009, the temporal trend in hip fractures requiring hospitalization was analyzed using an overdispersed Poisson regression model. Generalized Estimating Equations were used to assess the adjusted effect of dialysis modality on hip fractures. Results: 842,028 HD and 87,086 PD patients were included. There was a significant temporal increase in hip fractures in both HD and PD with stabilization of rates after 2005. With stratification, the increase in fractures occurred in patients who were white and over 65 years of age. In adjusted analyses, HD patients had 1.6 times greater odds of hip fracture than PD patients (OR 1.60 95% CI 1.52, 1.68, p < 0.001). Conclusions: In contrast to the declining hip fracture rates in the general population, we identified a temporal rise in incidence of hip fractures in HD and PD patients. HD patients were at a higher risk for hip fractures than PD patients after adjustment for recognized bone fragility risk factors. The increase in fracture rate over time was limited to older white patients in both HD and PD, the demographics being consistent with osteoporosis risk. Further research is indicated to better understand the longitudinal trend in hip fractures and the discordance between HD and PD. i 2014 S. Karger AG, Basel

Intravenous Iron Exposure and Outcomes in Patients on Hemodialysis

Iron is an essential trace element that is important for normal body function. However, excess iron in animal studies has been shown to be toxic, because it can enhance radical oxygen generation, impair neutrophil and T-cell function, and also promote bacterial growth ([1][1],[2][2]). This dichotomy