Incidence and Outcomes of Contrast-Induced AKI Following Computed Tomography

Background and objectives: Most studies of contrast-induced acute kidney injury (CIAKI) have focused on patients undergoing angiographic procedures. The incidence and outcomes of CIAKI in patients undergoing nonemergent, contrast-enhanced computed tomography in the inpatient and outpatient setting were assessed.Design, setting, participants, & measurements: Patients with estimated glomerular filtration rates (GFRs) <60 ml/min per 1.73 m² undergoing nonemergent computed tomography with intravenous iodinated radiocontrast at an academic VA Medical Center were prospectively identified. Serum creatinine was assessed 48 to 96 h postprocedure to quantify the incidence of CIAKI, and the need for postprocedure dialysis, hospital admission, and 30-d mortality was tracked to examine the associations of CIAKI with these medical outcomes.Results: A total of 421 patients with a median estimated GFR of 53 ml/min per 1.73 m² were enrolled. Overall, 6.5% of patients developed an increase in serum creatinine ≥25%, and 3.5% demonstrated a rise in serum creatinine ≥0.5 mg/dl. Although only 6% of outpatients received preprocedure and postprocedure intravenous fluid, <1% of outpatients with estimated GFRs >45 ml/min per 1.73 m² manifested an increase in serum creatinine ≥0.5 mg/dl. None of the study participants required postprocedure dialysis. Forty-six patients (10.9%) were hospitalized and 10 (2.4%) died by 30-d follow-up; however, CIAKI was not associated with these outcomes.Conclusions: Clinically significant CIAKI following nonemergent computed tomography is uncommon among outpatients with mild baseline kidney disease. These findings have important implications for providers ordering and performing computed tomography and for future clinical trials of CIAKI.The intravascular administration of iodinated contrast media is a well-recognized cause of acute kidney injury, which in turn, is associated with in-hospital morbidity and mortality (1–4). Clinical factors that increase the risk for contrast-induced acute kidney injury (CIAKI) include preexistent kidney disease, diabetes mellitus in the setting of underlying renal impairment, advanced congestive heart failure, intravascular volume depletion, administration of large volumes of contrast, and the use of high-osmolal contrast media (1,5–8). Much of our understanding of the risk factors for, incidence of, and outcomes associated with CIAKI emanate from clinical studies of patients undergoing angiography, particularly coronary angiography. Moreover, most clinical trials of preventive interventions, such as N-acetylcysteine (NAC) and intravenous (IV) fluids, have been conducted in patients undergoing angiographic procedures (9–15). Despite this, expert recommendations for the prevention of CIAKI make little distinction between patients undergoing cardiac catheterization and other contrast-enhanced procedures, or in the status of the patient at the time of the radiographic procedure (outpatient versus hospitalized) in regard to determining patients’ risk level for CIAKI or implementing preventive measures (6,16–18). Additionally, it remains unclear whether the morbidity and mortality that have been associated with CIAKI among hospitalized patients are present among outpatients.A large proportion of patients who receive intravascular iodinated contrast do so when undergoing outpatient computed tomography. The routine assessment of risk status and implementation of preventive interventions, such as IV fluid, are considerably more difficult in patients who undergo elective computed tomography than coronary angiography. The practical and fiscal challenges to systematically administering preprocedure and postprocedure IV fluid to “at risk” patients are substantial, particularly in the outpatient setting. However, to determine the most effective and practical approach to identifying patients at increased risk for CIAKI following computed tomography and implementing preventive care to those most likely to derive benefit, greater clarity is needed on the incidence and clinical sequelae of CIAKI in this patient population. The primary aim of this study was to assess the incidence and outcomes of CIAKI following nonemergent computed tomography in the inpatient and outpatient setting.     

Serotonin-Norepinephrine Reuptake Inhibitors and the Risk of AKI: A Cohort Study of Eight Administrative Databases and Meta-Analysis

Background and objectives

A safety signal regarding cases of AKI after exposure to serotonin-norepinephrine reuptake inhibitors (SNRIs) was identified by Health Canada. Therefore, this study assessed whether the use of SNRIs increases the risk of AKI compared with selective serotonin reuptake inhibitors (SSRIs) and examined the risk associated with each individual SNRI.

Design, setting, participants, & measurements

Multiple retrospective population-based cohort studies were conducted within eight administrative databases from Canada, the United States, and the United Kingdom between January 1997 and March 2010. Within each cohort, a nested case-control analysis was performed to estimate incidence rate ratios (RRs) of AKI associated with SNRIs compared with SSRIs using conditional logistic regression, with adjustment for high-dimensional propensity scores. The overall effect across sites was estimated using meta-analytic methods.

Results

There were 38,974 cases of AKI matched to 384,034 controls. Current use of SNRIs was not associated with a higher risk of AKI compared with SSRIs (fixed-effect RR, 0.97; 95% confidence interval [95% CI], 0.94 to 1.01). Current use of venlafaxine and desvenlafaxine considered together was not associated with a higher risk of AKI (RR, 0.96; 95% CI, 0.92 to 1.00). For current use of duloxetine, there was significant heterogeneity among site-specific estimates such that a random-effects meta-analysis was performed showing a 16% higher risk, although this risk was not statistically significant (RR, 1.16; 95% CI, 0.96 to 1.40). This result is compatible with residual confounding, because there was a substantial imbalance in the prevalence of diabetes between users of duloxetine and users of others SNRIs or SSRIs. After further adjustment by including diabetes as a covariate in the model along with propensity scores, the fixed-effect RR was 1.02 (95% CI, 0.95 to 1.10).

Conclusions

There is no evidence that use of SNRIs is associated with a higher risk of hospitalization for AKI compared with SSRIs.     

Correction to: Incidence of Hepatocellular Carcinoma in Primary Biliary Cholangitis: A Systematic Review and Meta-Analysis

Digestive Diseases and Sciences - The original version of the article unfortunately contained an error in the first name and the surname of the third author.     

The Incidence of New Vertebral Fractures Following Vertebral Augmentation: A Meta-Analysis of Randomized Controlled Trials

A meta-analysis of randomized controlled trials was performed that compares the relationship between percutaneous vertebral augmentation (PVA) and conservative treatments with the incidence of new vertebral fractures.Using meta-analytic techniques, this study compares PVA and conservative treatment for incidence of new vertebral fractures, particularly incidence of adjacent fractures that occur following treatment.A focus of clinicians has been on whether PVA increases the risk of new vertebral fractures.Pubmed, EMBASE, and the Cochrane Central Register of Controlled Trials were searched to retrieve literature published from the establishment of the databases until April 28, 2015. Literature of related areas was searched manually. The main outcome indicator was the incidence of new vertebral fractures at final follow-up appointment. In addition, we evaluated the incidence of new vertebral fractures in different follow-up periods and the incidence of adjacent fractures. The RevMan 5.3 software program of the Cochrane Collaboration was used to analyze the data. For dichotomous variables, the risk ratio (RR) and a confidence interval (CI) of 95% were used to express the heterogeneity of the effect size.Seven randomized controlled trial studies were selected from the literature. The studies include 871 patients, 436 of whom received PVA treatment and the rest received conservative treatment. Combined analysis of the 7 studies showed that the numbers of new vertebral fractures in the 2 groups are not significantly different. Six studies reported the numbers of new adjacent fractures. Considering the heterogeneity among the studies, 2 subgroups were formed. The 5 studies in the European group showed that the incidence of new adjacent fractures in the PVA-treated group is higher than that in the conservatively treated group, and the difference is statistically significant. The one study in the Asian group showed no significant difference between the incidences of adjacent fractures in the 2 groups.PVA treatment does not increase the incidence of new vertebral fractures. Most studies reported that PVA increases the incidence of adjacent fractures, yet it is rarely stated that both PVA and conservative treatment lead to the same incidence of adjacent fractures.     

A Patient with AKI after Cardiac Surgery

Up to 30% of patients undergoing cardiac surgery develop AKI, with 1% requiring RRT. AKI is an independent risk factor for morbidity and mortality. Postoperatively, even minimal changes in serum creatinine are associated with a substantial increase in mortality. No intervention has been definitely proven effective in reducing kidney injury. The successful prevention and management of AKI involves identifying patients at risk for AKI, recognizing subtle abnormalities in a timely manner, performing basic clinical assessments, and responding appropriately to data obtained. With that in mind, in this Attending Rounds, a woman with AKI in the setting of cardiac surgery is presented to highlight the use of history, physical exam, hemodynamic monitoring, laboratory data trends, and urine indices in establishing the correct diagnosis and appropriate management.     

Dialysis versus Nondialysis in Patients with AKI: A Propensity-Matched Cohort Study

Background and objectives

The benefit of the initiation of dialysis for AKI may differ depending on patient factors, but, because of a lack of robust evidence, the decision to initiate dialysis for AKI remains subjective in many cases. Prior studies examining dialysis initiation for AKI have examined outcomes of dialyzed patients compared with other dialyzed patients with different characteristics. Without an adequate nondialyzed control group, these studies cannot provide information on the benefit of dialysis initiation. To determine which patients would benefit from initiation of dialysis for AKI, a propensity-matched cohort study was performed among a large population of patients with severe AKI.

Design, setting, participants, & measurements

Adults admitted to one of three acute care hospitals within the University of Pennsylvania Health System from January 1, 2004, to August 31, 2010, who subsequently developed severe AKI were included (n=6119). Of these, 602 received dialysis. Demographic, clinical, and laboratory variables were used to generate a time-varying propensity score representing the daily probability of initiation of dialysis for AKI. Not-yet-dialyzed patients were matched to each dialyzed patient according to day of AKI and propensity score. Proportional hazards analysis was used to compare time to all-cause mortality among dialyzed versus nondialyzed patients across a spectrum of prespecified variables.

Results

After propensity score matching, covariates were well balanced between the groups, and the overall hazard ratio for death in dialyzed versus nondialyzed patients was 1.01 (95% confidence interval, 0.85 to 1.21; P=0.89). Serum creatinine concentration modified the association between dialysis and survival, with a 20% (95% confidence interval, 9% to 30%) greater survival benefit from dialysis for each 1-mg/dl increase in serum creatinine concentration (P=0.001). This finding persisted after adjustment for markers of disease severity. Dialysis initiation was associated with more benefit than harm at a creatinine concentration≥3.8 mg/dl.

Conclusions

Dialysis was associated with increased survival when initiated in patients with AKI who have a more elevated creatinine level but was associated with increased mortality when initiated in patients with lower creatinine concentrations.     

Biomarkers of AKI: A Review of Mechanistic Relevance and Potential Therapeutic Implications

AKI is a common clinical condition associated with a number of adverse outcomes. More timely diagnosis would allow for earlier intervention and could improve patient outcomes. The goal of early identification of AKI has been the primary impetus for AKI biomarker research, and has led to the discovery of numerous novel biomarkers. However, in addition to facilitating more timely intervention, AKI biomarkers can provide valuable insight into the molecular mechanisms of this complex and heterogeneous disease. Furthermore, AKI biomarkers could also function as molecular phenotyping tools that could be used to direct clinical intervention. This review highlights the major studies that have characterized the diagnostic and prognostic predictive power of these biomarkers. The mechanistic relevance of neutrophil gelatinase–associated lipocalin, kidney injury molecule 1, IL-18, liver-type fatty acid–binding protein, angiotensinogen, tissue inhibitor of metalloproteinase-2, and IGF-binding protein 7 to the pathogenesis and pathobiology of AKI is discussed, putting these biomarkers in the context of the progressive phases of AKI. A biomarker-integrated model of AKI is proposed, which summarizes the current state of knowledge regarding the roles of these biomarkers and the molecular and cellular biology of AKI.     

Spatial Abilities and Aging: A Meta-Analysis

Background/Study Context: Age-related effects in performance on spatial tasks have been well documented, with results suggesting a negative effect on performance in older samples. Although meta-analyses have been conducted examining performance on specific spatial tasks, it appears that data incorporating a variety of tasks have not yet been integrated into a single meta-analyses.

Methods: The present study examined age-related effects on spatial abilities in a multilevel meta-analysis of 137 effect sizes, drawn from 80 samples dated between 1958 and 2011. In addition to sample characteristics (education, year of publication, and age range), procedural factors (spatial ability category, spatial task, dependent variable, task setting, and medium of administration) were also considered. The standardized mean difference (Cohen’s d) was used as the effect size measure in meta-analytic calculations.

Results: Results revealed a large (mean d = 1.01) age-related decrease in spatial performance on psychometric tests. Specifically, older adults (mean age range = 63–79.5 years) performed worse on psychometric tests than younger adults (mean age range = 17–28.6 years). Interestingly, this age effect was unaffected by factors such as specific test, test category (mental rotation, spatial perception, or spatial visualization), timing conditions, and group or individual administration. However, measures of response time produced significantly larger effects of age than measures of accuracy on spatial performance.

Conclusion: The present analysis demonstrates a clear pattern of negative age effects in spatial ability across the literature. Although these effects are unaffected by the specific spatial component under investigation or testing conditions, speed of processing was shown to be an important factor in spatial performance. The need to report more thoroughly on characteristics of young and old participants in future studies is also emphasized.