Mortality in critical illness: The impact of asymmetric dimethylarginine on survival-A systematic review and meta-analysis.

INTRODUCTION: Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of the nitric oxide system, may be associated with an adverse outcome in critically ill patients. The aim of the present review was to clarify if plasma ADMA and the arginine-to-ADMA ratio (arginine/ADMA) are associated with mortality in critically ill patients. METHODS: We searched PubMed, EMBASE and Web of Science/BIOSIS Previews on 31 July 2017 for studies published after 2000 including critically ill paediatric or adult patients and evaluating any association between all-cause mortality and admission ADMA and/or arginine/ADMA ratio. We pooled data from studies providing sufficient data in random effects meta-analyses. RESULTS: We identified 15 studies including a total of 1300 patients. These studies have a medium to high risk of bias and substantial clinical heterogeneity. After contacting authors for homogenous data, six studies including 705 patients could be included in a formal meta-analysis. This analysis revealed a strong association between high plasma ADMA upon admission and mortality (pooled odds ratio 3.13; 95% confidence interval (CI) 1.78-5.51). A significant association between ADMA/arginine ratio and mortality was found in two studies only (54 patients) out of a total of six studies (564 patients). CONCLUSIONS: A high plasma ADMA level upon admission is strongly associated with mortality in critically ill patients. However, there is no association between the arginine/ADMA ratio and mortality in this group of patients. The pathophysiological role of ADMA in circulatory collapse and its potential as a target for intervention remains to be explored.

High Levels of Methylarginines Were Associated With Increased Mortality in Patients With Severe Sepsis.

INTRODUCTION: Nitric oxide (NO) likely plays a pivotal role in the pathogenesis of sepsis. Arginine is a substrate for NO, whereas the methylated arginines-asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA)-are endogenous by-products of proteolysis that inhibit NO production.We investigated if high-plasma levels of ADMA, SDMA, and arginine/ADMA ratio were associated with 90-day mortality in patients with severe sepsis or septic shock. METHODS: We included 267 adult patients admitted to intensive care unit with severe sepsis or septic shock. The patients had previously been included in the randomized controlled trial "Scandinavian Starch for Severe Sepsis and Septic Shock (6S)." ADMA, SDMA, and arginine/ADMA ratio were measured in plasma. The risk of death within 90 days was estimated in multivariate Cox regression analyses adjusted for gender, age ≥65 years, major cardiovascular disease, diabetes, hypertension, respiratory failure, vasopressor treatment, highest quartile of creatinine and bilirubin, and lowest quartile of platelet count. In the regression analyses missing values were estimated using multiple imputation. RESULTS: Twenty-five patients had missing data in one or more of the baseline variables and 44 patients had missing methylarginine values. Both ADMA and SDMA were independently associated with 90-day mortality (ADMA: hazard ratio 1.54; 95% CI, 1.00-2.38; P = 0.046, and SDMA: hazard ratio 1.78; 95% CI, 1.14-2.72; P = 0.011). Arginine/ADMA ratio was not associated with 90-day mortality neither in univariate nor in multivariate analyses. The difference in mortality between patients with high and low ADMA was most pronounced in the first week after inclusion. CONCLUSIONS: High levels of ADMA and SDMA in plasma were associated with increased 90-day mortality in patients with severe sepsis or septic shock. Interfering with the methylarginine-NO systems may be a novel target in these patients.