Resting heart rate and risk of metabolic syndrome in adults: a dose–response meta-analysis of observational studies

The magnitude of the risk of metabolic syndrome (MetS) with increased resting heart rate (RHR) has been inconsistently reported in some observational studies, and whether a dose–response relationship exists between RHR and MetS is unclear. We performed a meta-analysis including dose–response analysis to quantitatively evaluate this association in adults. We searched PubMed, Web of Knowledge, China National Knowledge Infrastructure, and WanFang databases for articles published up to April 2, 2016. A random-effects model was used to pool relative risks (RRs) and 95% confidence intervals (CIs); restricted cubic spline function was used to assess the dose–response relationship. Seven prospective cohort studies and 10 cross-sectional studies with a total of 169,786 participants were included. The pooled RR was 2.10 (95% CI 1.80–2.46, I2 = 79.8%, n = 13) for the highest versus reference RHR category and 1.28 (95% CI 1.23–1.34, I2 = 87.7%, n = 15) for each 10 beats per minute (bpm) increment in RHR. We found no evidence of a nonlinear dose–response association between RHR and MetS (Pnonlinearity = 0.201). The relationship was consistent in most subgroup analyses and robust on sensitivity analysis. No significant publication bias was observed. This meta-analysis suggests that risk of MetS may be increased with elevated RHR.