Sex differences in the association between ideal cardiovascular health and biomarkers of cardiovascular disease among adults in the United States: a cross-sectional analysis from the multiethnic study of atherosclerosis =========================================================================================================================================================================================================================== * Olatokunbo Osibogun * Oluseye Ogunmoroti * Martin Tibuakuu * Eve-Marie Benson * Erin D Michos ## Abstract **Objectives** This study investigated the sex differences in the associations between ideal cardiovascular health (CVH), measured by the American Heart Association’s Life’s Simple 7 metrics, and cardiovascular disease (CVD)-related biomarkers among an ethnically diverse cohort of women and men free of clinical CVD at baseline. **Setting** We analysed data from the Multi-Ethnic Study of Atherosclerosis conducted in six centres across the USA (Baltimore, Maryland; Chicago, Illinois; Forsyth County, North Carolina; Los Angeles, California; New York, New York; and St Paul, Minnesota). **Participants** This is a cross-sectional study of 5379 women and men, aged 45–84 years old. Mean age (SD) was 62 (10), 52% were women, 38% White, 11% Chinese American, 28% Black and 23% Hispanic. **Primary measures** The seven metrics (smoking, body mass index, physical activity, diet, total cholesterol, blood pressure and blood glucose) were each scored as 0 points (poor), 1 point (intermediate) or 2 points (ideal). The total CVH score ranged from 0 to 14. The CVD-related biomarkers studied were high-sensitivity C-reactive protein, D-dimer, fibrinogen, homocysteine, high-sensitivity cardiac troponin T, N-terminal pro B-type natriuretic peptide (NT-proBNP) and interleukin 6. We examined the association between the CVH score and each biomarker using multivariable linear regression, adjusting for age, race/ethnicity, education, income and health insurance status. **Results** Higher CVH scores were associated with lower concentrations of all biomarkers, except for NT-proBNP where we found a direct association. There were statistically significant interactions by sex for all biomarkers (p<0.001), but results were qualitatively similar between women and men. **Conclusion** A more favourable CVH score was associated with lower levels of multiple CVD-related biomarkers for women and men, except for NT-proBNP. These data suggest that promotion of ideal CVH would have similarly favourable impact on the reduction of biomarkers of CVD risk for both women and men. * biomarkers * cardiovascular disease * ideal cardiovascular health metrics * life’s simple 7 * sex * gender ### Strengths and limitations of this study * Use of a large and diverse study sample that enabled stratification by sex, race/ethnicity and age. * Use of validated survey instruments and standardised methods for data collection allowed for comparison with other studies. * Study population included adults between the ages of 45 and 84 years, which limits the generalisability of our findings to younger or older age groups. * Cross-sectional design cannot establish temporality or causation. ## Introduction The ideal cardiovascular health (CVH) construct, defined as meeting specific criteria for seven health behaviours and health factors called the Life’s Simple 7 (LS7) metrics, was introduced by the American Heart Association (AHA) to decrease the burden of cardiovascular disease (CVD).1 This was a shift towards primordial prevention—focusing on wellness rather than disease.2 Biomarkers, which are often used in conjunction with traditional risk factors, are subclinical indicators of physiological and pathological processes3 and serve as useful tools in facilitating early detection and prognostication of CVD.4 Although prior studies have examined the relationship of biomarkers with incident CVD, few have focused on biomarkers and measures of cardiovascular wellness. Not surprisingly, the studies that have examined the association between ideal CVH and subclinical biomarkers of disease have shown an inverse relationship.5 For example, in a prior analysis from the Multi-Ethnic Study of Atherosclerosis (MESA), poor CVH was found to be associated with higher levels of GlycA (a novel inflammatory marker) and higher levels of traditional inflammatory markers [high-sensitivity C-reactive protein (hsCRP), interleukin 6 (IL-6), fibrinogen and D-dimer].6 However, research on the sex differences of the relationship of CVH with CVD-related biomarkers is sparse.7 Women are known to have higher levels of hsCRP8 9 and N-terminal pro B-type natriuretic peptide (NT-proBNP)10 than men even after accounting for cardiometabolic risk factors, while troponin levels are higher in men than women.11 12 Thus, understanding sex differences in the relationship of ideal CVH measures with biomarkers is an important intermediate step in explaining sex differences in clinical CVD. This study aimed to examine the sex differences in the associations between ideal CVH and CVD-related biomarkers among women and men free of clinical CVD in an ethnically diverse cohort. We hypothesised that better CVH would be associated with lower concentrations of CVD-related biomarkers especially in women. ## Methods ### Study population As previously described, MESA is a longitudinal study of 6814 adult women and men between the ages of 45 and 84 years. The study participants, with no previous history of clinical CVD at baseline, were recruited from six centres (Baltimore, Maryland; Chicago, Illinois; Forsyth County, North Carolina; Los Angeles, California; New York, New York; and St Paul, Minnesota) in the USA between July 2000 and August 2002.13 Among participants, 38% were White, 11% Chinese American, 28% Black and the remaining 23% were Hispanic. Informed consent was provided by all participants. The MESA protocol was approved by the institutional review boards (IRB) of all the recruitment centres. At the Johns Hopkins field centre where this analysis was conducted, the IRB approval number was NA_00030361. Baseline information was collected using standardised questionnaires, physical examinations and fasting laboratory blood draw. For the current analyses, we included 5379 participants from the MESA baseline examination after excluding participants with missing information for the CVD biomarkers and LS7 metrics. ### Assessment of biomarkers We examined biomarkers that were measured at baseline. Fasting blood samples were drawn, processed and stored using standardised procedures.14 HsCRP, D-dimer, fibrinogen, IL-6 and homocysteine levels were analysed at the laboratory for Clinical Biochemistry Research (University of Vermont, Burlington, Vermont, USA). Serum levels of hsCRP (mg/L) were measured using the BNII nephelometer (Dade Behring, Deerfield, Illinois, USA). Analytical intra-assay coefficients of variation (CV) of hsCRP ranged from 2.3% to 4.4%, and inter-assay CV ranged from 2.1% to 5.7%.6 15 D-dimer (μg/mL) was measured with an immunoturbidimetric assay (Liatest D-DI; Diagnostica Stago, Parsippany, New Jersey, USA) which was used on a Sta-R analyser (Diagnostica Stago, Parsippany, New Jersey, USA). The lower detection limit of D-dimer assay was 0.01 µg/mL.6 Serum fibrinogen (mg/dL) was measured by immunoprecipitation of fibrinogen antigen using the BNII nephelometer (N Antiserum to Human Fibrinogen; Dade Behring, Deerfield, Illinois, USA). The intra-assay and inter-assay CV were 2.7% and 2.6%, respectively.6 15 Serum IL‐6 (pg/mL) was measured by ultrasensitive ELISA (Quantikine HS Human IL‐6 Immunoassay; R&D Systems, Minneapolis, Minnesota). The analytical CV was 6.3%.15 Plasma homocysteine (μmol/L) was measured using a fluorescence polarisation immunoassay with the IMx analyser (Abbott Diagnostics, Abbott Park, Illinois, USA). The CV was 4.5%.16 The assays for high-sensitivity cardiac troponin T (hs-cTnT, ng/L) and NT-proBNP (pg/mL) were performed at the Veteran’s Affairs San Diego Healthcare System (La Jolla, California, USA) and measured in serum using the Elecsys 2010 system (Roche Diagnostics, Indianapolis, Indiana, USA). For hs-cTnT, the inter-assay CV observed for the MESA cohort measurements were 3.6% at 28 ng/L and 2.0% at 2154 ng/L.17 For NT-proBNP, the intra-assay and inter-assay CV were as follows: at 175 pg/mL, 2.7% and 3.2%; at 355 pg/mL, 2.4% and 2.9%; at 1068 pg/mL, 1.9% and 2.6%; and at 4962 pg/mL, 1.8% and 2.3%, respectively.10 ### Assessment of cardiovascular health Cardiovascular health was assessed at baseline using the LS7 metrics based on AHA criteria.1 A detailed assessment can be found in the supplementary material (online Supplementary Methods). ### Supplementary data [[bmjopen-2019-031414supp001.pdf]](pending:yes) ### Assessment of covariates Sociodemographic factors included as covariates are age, sex, race/ethnicity, education, income and health insurance. Age was examined as a continuous variable in the multivariable models but dichotomised as <65 and≥65 years for subgroup testing. Race/ethnicity had four groups: White, Chinese American, Black and Hispanic. We had nine categories for education and 13 categories for income (online supplementary table 1), which were used in our multivariable models; however, they were dichotomised as ≥bachelor’s degree and