Elevated resting heart rate predisposes metabolic syndrome in women rather than in men: a 15-year prospective study

BACKGROUND: Increasing evidences have indicated that there are gender differences in the prevalence of metabolic syndrome(MS), but the mechanism is uncertain. METHODS: A total of 711 subjects aged 35-65 years accepted health examinations both in 1992 and 2007. Since 114 subjects had MS and 7 had heart disease at baseline, they were excluded from the analysis. Therefore, 590 subjects with complete data (male: 61.5 %) were available and analysed. After the relationship between gender and incident MS at follow-up was tested, these subjects were categorized into four groups according to the baseline resting heart rate(RHR) classified by genders. Trend tests of MS incidences across the four groups of resting heart rate were conducted by Cochran-Armitage tend tests in both men and women. Additionally, three logistic regression models were used to estimate the effects of RHR on the new onset of MS by taking RHR as a continuous variable(per 4 beats/min elevation). RESULTS: Gender(women) itself was an independent risk factor for incident MS at follow-up(OR = 2.64, 1.33-5.23, P = 0.005). The incidences of MS according to the RHR categories showed a statistical linear trend in women(P for trend = 0.018) rather than in men(P for trend = 0.194). The ORs[95 % confidence intervals(CIs)] of MS for each 4 bpm elevation in RHR was 1.18(1.03-1.36)(P = 0.020) in a univariate model, 1.20 (1.04-1.38) (P = 0.011) adjusted for age and health related behaviors only and 1.23(1.06-1.43)(P = 0.007) adjusted for age, health related behaviors and pre-existing components of MS in the baseline in women. Otherwise, RHR did not have any significant associations with incident MS in men neither in a univariate model nor in multivariate models. CONCLUSIONS: In this study, elevated RHR is correlated with the development of MS in women rather than in men.