Adiponectin levels and the risk of hypertension: a systematic review and meta-analysis

Abstract

Animal studies and small controlled studies in humans suggest that adiponectin may regulate blood pressure via brain-mediated and endothelium-mediated mechanisms. We performed a systematic review and meta-analysis to evaluate the epidemiological evidence on plasma adiponectin levels and hypertension in free-living adult population. A systematic search of MEDLINE and EMBASE, up to February 2013, identified 43 nonprospective and 5 prospective studies that included 17 598 adults (8220 with hypertension; mean age 19-69 years; and mean body mass index 22-38 kg/m(2)). Two investigators independently extracted data on adiponectin levels by hypertension status and dose-response relationship. We used a random-effects model to compute the weighted mean difference in adiponectin levels between adults with hypertension and normotensive adults and a 2-stage generalized least-square trend methods to compute the odds ratio of hypertension per 1 µg/mL increase in adiponectin. Adults with hypertension had 1.64 µg/mL (95% confidence interval, -2.07, -1.21) lower adiponectin levels than normotensive adults. Every 1 µg/mL increase in adiponectin levels was associated with 6% reduced risk of hypertension (95% confidence interval, 0.92, 0.97). These findings were consistent across study design and characteristics, including age, sex, and body mass index (P>0.05). However, our meta-analysis was limited by unexplained large between-study heterogeneity, a small number of prospective studies, and selective reporting of dose-response data. In conclusion, epidemiological evidence suggests that plasma adiponectin level is a biomarker and possible mediator in the development of adiposity-related hypertension. The question remains as to adiponectin as a potential therapeutic target and its relationship with other adipokines in blood pressure regulation.

Keywords: adiponectin; blood pressure; hypertension; obesity; review, systematic.

Conflict of interest statement

CONFLICT OF INTEREST/DISCLOSURES

None.

Figures

Figure. Adjusted Odds Ratio of Hypertension According to Adiponectin Level*

* Adjusted odds ratios of hypertension were plotted against the median value of adiponectin quantile in 7 studies that reported 9 quantile-specific dose-response data points. The size of markers is proportional to the inverse variance of the quantile-specific odds ratios. The fitted line (thick solid line) and 95% confidence interval (shaded area) were estimated from a linear-spine generalized least-squares trend model with the knot 8 μg/ml (p=0.002 for the linear spline term).