Adiponectin is associated with increased mortality in patients with already established cardiovascular disease: a systematic review and meta-analysis.

BACKGROUND: The overall quantitative estimate on the possible association of adiponectin concentrations with mortality in patients with cardiovascular diseases (CVD) has not been reported. METHODS: We performed a systematic review and meta-analysis of prospective studies to evaluate the overall quantitative estimates on the adiponectin levels for risk of mortality in patients with CVD. MEDLINE, EMBASE, CINAHL, and the Cochrane Library (up to Mar 22, 2014) were used to search for studies evaluating the effect of adiponectin levels on mortality in patients with CVD. Random-effect models were selected to estimate overall effect estimates. RESULTS: Data from 14063 CVD patients enrolled in 15 prospective cohort and 1 nested case control studies were collated. The meta-analyses showed strong positive association of adiponectin with all-cause (n=14 studies, overall pooled effect estimate=1.45 [95% CI, 1.17-1.79]) and cardiovascular (n=11 studies, overall pooled effect estimate=1.69 [1.35-2.10]) mortality, for the highest tertile of adiponectin levels versus the lowest tertile. Subgroup analyses show study characteristics (including effect estimate, mean age, study location, sample sizes, gender, durations of follow-up, types of primary event, and acute or chronic CVD) did not substantially influence these positive associations. CONCLUSIONS: Our results showed that increased baseline plasma adiponectin levels are significantly associated with elevated risk of all-cause and cardiovascular mortality in subjects with CVD. These positive associations may have been amplified by adjustment for potential intermediates or residual confounding, and their basis requires further investigation.