American Association for Clinical Chemistry
Better health through laboratory medicine
October 2008 Clinical Laboratory News: Diagnostics Profiles

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October 2008: Volume 34, Number 10

 Homocysteine-Lowering B Vitamins Yield No Benefit Post Angiography

A randomized, double-blinded trail of more than 3,000 patients who had received coronary angiography found that administration of folic acid with vitamin B12 was not associated with any effect on mortality or cardiovascular events (JAMA 2008;300:795–804). Patients were enrolled from two Norwegian hospitals and divided into four groups: folic acid and B6; folic acid and B12; B6 only; and a control group that received a placebo. Mean patient age was approximately 61 years in each group, and participants were followed for a mean of 38 months. Researchers stopped the trial early because preliminary results from another trial in Norway suggested an increased risk for adverse events associated with B12 supplementation. Final results of the study showed the rate of all-cause mortality was 12.2% in patients given B6 and B12, 16.3% in those given folic acid and B12, 13.7% in those given B6 alone, and 12.5% in those given a placebo. Supplementation with either folic acid or B12 did reduce the level of homocysteine in the blood by 30%, however.

Meta-Analysis Shows Tight Glucose Control Fails to Cut Deaths

A meta-analysis of adult patients in the ICU found that tight glycemic control did not confer a lower risk of death but did increase the risk of hypoglycemia and reduce the risk of septicemia (JAMA 2008;300:933–44). The study included 29 randomized, controlled trials and 8,432 patients. For the primary outcome of hospital mortality, there was no significant difference between patients receiving usual care and those under tight glycemic control (21.6% and 23.3%, respectively). In addition, there was no difference in mortality corresponding with very tight control (≤110 mg/dL) versus moderately tight control (<150 mg/dL). Nor was there an increase in mortality associated with the surgical ICU (8.8%) vs. the medical ICU (26.9%). However, when results were stratified by ICU setting, the risk of septicemia was reduced only in surgical ICU patients. According to the authors, the findings of the meta-analysis suggest “that the guidelines recommending tight glucose control in all critically ill patients should be reevaluated until the results of larger, more definitive clinical trials are available.”


Anemia Boosts Death Risk in Patients With HF

Anemia is linked to a significantly increased risk of death in patients with heart failure, according to the first meta-analysis to examine the topic (Journal of the American College of Cardiology 2008;52: 818–27). The investigators performed a literature search of all published English-language studies and assessed each for quality, in accordance with the guidelines of the U.S. Preventive Task Force and other recommendations. They included 34 reports in their analysis, with a total of 153,180 patients, of whom 37.2% were anemic, as defined by the original reports. At follow-up of at least 6 months, 46.8% of anemic patients had died, versus 29.5% of those without anemia, for an odds ratio of 1.96. There was no difference in this increased mortality risk between patients with diastolic or systolic HF, the authors reported. After adjustment of mortality risk for age and renal function, a nearly 50% increased risk of mortality remained for HF patients (HR 1.46). The authors noted that an estimated 7%–50% of HF patients have anemia, according to previous reports. These findings suggest that future research should investigate ways to raise hemoglobin levels in patients with HF, the authors concluded. They noted that a phase III morbidity and mortality trial to assess the benefit of erythropoiesis-stimulating proteins (ESPs) in HF patients is under way.