| Abstract: | BACKGROUNDEpidemiologic studies have explored the association between a single cardiovascular risk factor (CVRF) and resting heart rate (RHR), but the research on the relation of multiple risk factors with RHR remains scarce. This study aimed to explore the associations between CVRFs clustering and the risk of elevated RHR.METHODSIn this cross-sectional study, adults aged 35–75 years from 31 provinces were recruited by the China PEACE Million Persons Projects from September 2015 to August 2020. We focused on seven risk factors: hypertension, diabetes mellitus, dyslipidemia, obesity, smoking, alcohol use, and low physical activity. Multivariate logistic regression was used to calculate odds ratios (OR) for elevated RHR (> 80 beats/min).RESULTSAmong 1,045,405 participants, the mean age was 55.67 ± 9.86 years, and 60.4% of participants were women. The OR (95% CI) for elevated RHR for the groups with 1, 2, 3, 4 and ≥ 5 risk factor were 1.11 (1.08–1.13), 1.36 (1.33–1.39), 1.68 (1.64–1.72), 2.01 (1.96–2.07) and 2.58 (2.50–2.67), respectively (Ptrend < 0.001). The association between the CVRFs clustering number and elevated RHR was much more pronounced in young males than in other age-sex subgroups. Clusters comprising more metabolic risk factors were associated with a higher risk of elevated RHR than those comprising more behavioral risk factors. CONCLUSIONSThere was a significant positive association between the CVRFs clustering number and the risk of elevated RHR, particularly in young males. Compared clusters comprising more behavioral risk factors, clusters comprising more metabolic risk factors were associated with a higher risk of elevated RHR. RHR may serve as an indicator of the cumulative effect of multiple risk factors.Over the past several years, the rapid development of smart wrist-worn devices has resulted in a convenient approach to monitoring resting heart rate (RHR) in daily life. RHR is becoming a promising indicator of cardiovascular health. Observational studies have shown that elevated RHR is associated with increased all-cause and cardiovascular mortality in populations with or without cardiovascular disease (CVD).[1,2] Elevated RHR has also been found to be associated with cardiovascular risk factors (CVRFs), such as hypertension, diabetes mellitus, dyslipidemia, low physical activity and smoking, indicating its potential to reflect total cardiac risk.[3–7] There is abundant epidemiologic evidence supporting the association between a single CVRF and RHR, but studies exploring associations between multiple CVRFs and RHR are limited. CVRFs tend to cluster within individuals, and several weak risk factors combined may result in a much higher risk than that due to a single strong risk factor. According to a cross-sectional survey in China, more than 45% of Chinese adults have two or more coexisting CVRFs.[8] Thus, it is important to consider the situation of multiple CVRFs clustering. However, very few studies have analyzed the association between CVRFs clustering and RHR, and several aspects remain unknown. Firstly, prior studies mainly focused on the relation between metabolic risk factors and RHR.[9–11] Behavioral risk factors such as smoking, physical activity and alcohol use have rarely been considered, even though these risk factors also have a significant effect on heart rate.[3,5,7] Secondly, most studies merely dealt with the relation of CVRFs clustering number with RHR, while regarding each number of risk factors, different combinations of risk factors have not yet been considered before.[9,12] It is important to consider different CVRF clustering patterns since some risk factors combined may lead to a higher risk of elevated RHR than others, even if the number of CVRFs is the same. Thirdly, prior studies did not assess associations stratified by sex and age. It has been well documented that RHR levels differ by sex and age. The RHR in women was on average 2–7 beats/min higher than that in men, and there was a decrease in the RHR with age.[13,14] As such, whether the associations of CVRFs clustering with RHR varied between sex and age remains unclear. Taking advantage of the large sample size in our study, we are able to include a wider range of CVRFs (metabolic and behavioral risk factors), comprehensively evaluate the association between these CVRFs clustering and RHR, and further explore sex and age differences. This finding may inform us whether RHR can be used as a simple and efficient metric for the identification of high-risk individuals who require more intensive risk factor evaluation and earlier cardiovascular health monitoring in resource-constrained countries with substantial CVD burdens, such as China. To bridge this knowledge gap, we used data from the China PEACE Million Persons Projects, a nationwide screening project, to explore (1) the association between the number of CVRFs clustering and elevated RHR in the overall population and populations stratified by age and sex; and (2) the associations between different CVRFs clusters and the risk of elevated RHR in the overall population and populations stratified by sex. |
