Association between adipokines and critical illness outcomes

BACKGROUND Adipose tissue is an endocrine organ that plays a critical role in immunity and metabolism by virtue of a large number of hormones and cytokines, collectively termed adipokines. Dysregulation of adipokines has been linked to the pathogenesis of multiple diseases, but some questions have arisen concerning the value of adipokines in critical illness setting. The objective of this review was to evaluate the associations between blood adipokines and critical illness outcomes. METHODS PubMed, CINAHL, Scopus, and the Cochrane Library databases were searched from inception through July 2016 without language restriction. Studies reporting the associations of adipokines, leptin, adiponectin, resistin, and/or visfatin with critical illness outcomes mortality, organ dysfunction, and/or inflammation were included. RESULTS A total of 38 articles were selected according to the inclusion/exclusion criteria of the study. Significant alterations of circulating adipokines have been reported in critically ill patients, some of which were indicative of patient outcomes. The associations of leptin and adiponectin with critical illness outcomes were not conclusive in that blood levels of both adipokines did not always correlate with the illness severity scores or risks of organ failure and mortality. By contrast, studies consistently reported striking increase of blood resistin and visfatin, independently of the critical illness etiology. More interestingly, increased levels of these adipokines were systematically associated with severe inflammation, and high incidence of organ failure and mortality. CONCLUSIONS There is strong evidence to indicate that increased levels of blood resistin and visfatin are associated with poor outcomes of critically ill patients, including higher inflammation, and greater risk of organ dysfunction and mortality. LEVEL OF EVIDENCE Systematic review, level III.