In This Issue...
Aldosterone, CRP Linked to Metabolic Syndrome in African-Americans
Higher levels of aldosterone and C-reactive protein (CRP) predict incident metabolic syndrome in African-Americans (Diabetes Care 2013;36:3084–92). These findings possibly are the first to explore the association between pathologies in the neurohormonal and inflammatory pathways and development of the metabolic syndrome specifically in African-Americans.
The data come from the Jackson Heart Study, the largest investigation of causes of cardiovascular disease in an African-American population. From the 5,301 participants in the overall Jackson Heart Study, this study involved 3,019 and 1,215 subjects from the first and second visits, conducted between 2000–2004 and 2005–2008, respectively. The researchers used lab results from the second visit to determine incident metabolic syndrome.
Based on statistical analysis of a panel of biomarker assessments, the authors found serum aldosterone, CRP, and B-type natriuretic peptide (BNP) to be significantly associated with development of metabolic syndrome, with adjusted odds ratios for aldosterone and CRP of 1.25 and 1.20, respectively. In the case of BNP, the authors found a curvilinear relationship, with increased odds of developing metabolic syndrome at both the lowest and highest quartiles. The authors speculated that this curvilinear association might be a reflection of the link between lower BNP levels and obesity and higher BNP concentrations and blood pressure, and they called for further studies to see if these findings can be replicated.
Neutrophil Counts, Ratio Better Identify Meningococcal Infection Than Total WBC
Results from the U.S. Multicenter Meningococcal Surveillance Study indicate that absolute neutrophil count (ANC), immature neutrophil count (INC), and immature-to-total neutrophil ratio (ITR) are better indicators of invasive meningococcal infection than total white blood cell (WBC) or total neutrophil count (Pediatr Infect Dis J 2013;32:1070–2). Based on these findings the authors suggested that serious bacterial infection should be considered in febrile children whose WBC counts meet even one ANC, INC, or ITR criterion used in the study.
The study involved 261 children admitted with invasive disease due to Neisseria meningitides, as identified by cerebral spinal fluid culture or rapid antigen test positivity for N. meningitides, of which 216 were included in the final analysis. The researchers pre-set thresholds for WBC count differentials that most physicians would find markedly abnormal, including ANC ≤1,000/mm3 or ≥10,000/mm3, INC ≥500/mm3, and ITR ≥0.20.
The authors found at least one or more of these criteria in 94% of the subjects included in the final analysis. However, they noted "completely normal" WBCs in 33% of cases, suggesting that relying on total WBC alone would have been falsely reassuring. Likewise, the authors wrote that an automated differential count also would have been falsely reassuring in 37% of cases in which ANC was normal or only mildly abnormal. This is because most automated differential counters report ANC but not bands or other immature neutrophils.
The investigators commented that children who present with an acute nonfocal febrile illness commonly are diagnosed as having viral syndrome, which may be inappropriate if the patient’s blood count meets any one of the criteria used in the study.
Poor Glycemic Control Linked to Worse Wound Closure Outcomes
Chronic and perioperative glucose management in high-risk patients undergoing surgical closure of their wounds is significantly associated with outcomes (Plast Reconstr Surg 2013;132:996–1003). This finding builds on prior research showing that for each 1.0 increase in HbA1c level, the daily wound area healing rate decreases by 0.029 cm2/day, and it gives providers information to risk-stratify and counsel patients prior to attempting surgical closure of their wounds.
The authors performed a retrospective analysis of 81 patients who underwent primary closure of their wounds. They analyzed both HbA1c and blood glucose levels for the 5 days before and after surgery and compared them with the primary endpoints of dehiscence, infection, and reoperation. The researchers found that any blood glucose measurement >200 mg/dL before or after surgery or HbA1c levels >6.5 were significantly associated with increased rates of dehiscence, with odds ratios of 3.2, 3.46, and 3.54 for glucose levels before, after, and HbA1c levels, respectively. Variability in preoperative blood glucose levels with a range >200 points was significantly associated with increased rates of reoperation, with an odds ratio of 4.14.
The researchers called for a team-based approach to glucose management in such medically complex patients, something that apparently is lacking, at least in teaching facilities, according to the authors. They cited a recent survey that showed only one-third of residents reported being current with existing glucose management guidelines. At the same time, fewer than one-third of attending physicians who relied heavily on residents to manage glucose control in perioperative patients indicated that they would consult other professionals for assistance.
Plasma NGAL Accurately Predicts Acute Kidney Injury in ED Patients
Plasma neutrophil gelatinase-associated lipocalin pNGAL is an accurate biomarker for predicting acute kidney injury (AKI) in patients admitted through the emergency department (ED) (Clin J Am Soc Nephrol 2013; doi: 10.2215/CJN.12181212). Although the findings need to be confirmed in other studies, they suggest that pNGAL might be useful in differentiating intrinsic AKI from transient reversible forms of renal dysfunction. According to the authors, patients seen in the ED with small increases in serum creatinine, the main biomarker used to identify AKI, often are mis-diagnosed. Yet earlier diagnosis of AKI could lead to better patient outcomes.
The study involved 616 patients who presented to the ED and were classified by clinical criteria as having AKI, transient azotemia, stable chronic kidney disease, or normal kidney function. The researchers took prospective serial measurements of serum creatinine, serum cystatin C, and pNGAL at 0, 6,12, 24, and 48 hours, respectively. They assessed pNGAL as a diagnostic test using the cut-offs of 100 ng/mL and 150 ng/mL.
Overall, the authors classified 21% of patients as having AKI; the highest median pNGAL levels were in the AKI group, ranging from 146–174 ng/mL at various time points. pNGAL levels rose with increasing AKI severity. The pNGAL area under the curve for discriminating AKI rose with higher grades of severity.
Based upon their findings, the investigators proposed three grades of AKI risk based on pNGAL concentrations: low, moderate, and high. In comparison to patients in the low-risk category, those in the moderate- and high-risk groups had significantly increased odds of developing AKI; 4.4 and 9.8, respectively.