Elsevier

Atherosclerosis

Volume 234, Issue 1, May 2014, Pages 102-107
Atherosclerosis

Comparing coronary artery calcium among U.S. South Asians with four racial/ethnic groups: The MASALA and MESA studies

https://doi.org/10.1016/j.atherosclerosis.2014.02.017Get rights and content

Highlights

  • Coronary artery calcium (CAC) prevalence was similar among South Asian & White men.

  • CAC was higher in South Asian men than African American, Latino and Chinese men.

  • South Asian women had similar CAC prevalence compared to all MESA women.

  • South Asian women ≥70 years had higher CAC prevalence than all other women.

Abstract

Objectives

South Asians (individuals from India, Pakistan, Bangladesh, Nepal, and Sri Lanka) have high rates of cardiovascular disease which cannot be explained by traditional risk factors. Few studies have examined coronary artery calcium (CAC) in South Asians.

Methods

We created a community-based cohort of South Asians in the United States and compared the prevalence and distribution of CAC to four racial/ethnic groups in the Multi-Ethnic Study of Atherosclerosis (MESA). We compared 803 asymptomatic South Asians free of cardiovascular disease to the four MESA racial/ethnic groups (2622 Whites, 1893 African Americans, 1496 Latinos and 803 Chinese Americans).

Results

The age-adjusted prevalence of any CAC was similar between White and South Asian men, but was lower in South Asian women compared to White women. After adjusting for all covariates associated with CAC, South Asian men were similar to White men and had higher CAC scores compared to African Americans, Latinos and Chinese Americans. In fully adjusted models, CAC scores were similar for South Asian women compared to all women enrolled in MESA. However, South Asian women ≥70 years had a higher prevalence of any CAC than most other racial/ethnic groups.

Conclusions

South Asian men have similarly high CAC burden as White men, but higher CAC than other racial/ethnic groups. South Asian women appear to have similar CAC burden compared to other women, but have somewhat higher CAC burden in older age. The high burden of subclinical coronary atherosclerosis in South Asians may partly explain higher rates of cardiovascular disease in South Asians.

Introduction

Individuals of South Asian ancestry (from India, Pakistan, Bangladesh, Nepal, and Sri Lanka) represent a quarter of the world's population and are second fastest growing ethnic minority group in the United States [1]. South Asians have a high rate of coronary heart disease which cannot be fully explained by traditional cardiovascular risk factors [2], [3], [4]. In California, South Asians have the highest incidence of coronary heart disease [5] and highest heart disease mortality of any racial/ethnic group [6].

Coronary artery calcium (CAC) measurement is a non-invasive method for determining atherosclerosis burden [7] and has been recommended for further cardiovascular risk assessment amongst intermediate risk individuals [8], [9], [10]. While CAC scores differ by race/ethnicity [11], [12], a significant association between CAC score and incident coronary heart disease events has been reported in each of the race/ethnic groups studied in the Multi-Ethnic Study of Atherosclerosis (MESA) [13]. Few studies have examined the distribution of CAC score in asymptomatic South Asians [14], [15], [16], and no studies have determined whether CAC scores help explain the high incidence of heart disease in South Asians.

We sought to determine the prevalence, burden, and associations of CAC among a community-based sample of asymptomatic South Asians in the U.S. compared to the four other racial/ethnic groups in MESA. We used data from the Mediators of Atherosclerosis in South Asians Living in America (MASALA) study which was modeled on MESA with similar protocols to allow for efficient cross-ethnic comparisons. We hypothesized that South Asian men and women would have higher overall CAC burden than other racial/ethnic groups.

Section snippets

Methods

The MASALA study is a community-based cohort of South Asian men and women from two clinical sites (San Francisco Bay Area at the University of California, San Francisco (UCSF) and the greater Chicago area at Northwestern University (NWU)). The baseline examination was conducted from October 2010 through March 2013. The institutional review boards of UCSF and NWU approved the MASALA study protocol.

The MASALA study methods and recruitment have been previously reported [17]. Briefly, to be

MESA study methods

The study design, eligibility and methods for MESA have been previously published [18]. MESA includes individuals from four racial/ethnic groups (Whites, African Americans, Latinos and Chinese Americans). We used data from the baseline MESA examination (2000–2002). Identical questionnaires for socio-demographic characteristics and physical activity and protocols for seated blood pressure, anthropometry and cardiac CT scanning were used as described above.

To have similar age range of

Statistical analyses

Baseline characteristics of the MASALA participants were compared to each of the MESA racial/ethnic groups using ANOVA for continuous variables and chi-squared tests of homogeneity for categorical variables. CAC scores were analyzed as a dichotomous outcome for any prevalent CAC, as a continuous outcome using ln(CAC+1), and as a categorical outcome. We compared the prevalence, mean, and distribution of CAC score categories between South Asians and the four MESA racial/ethnic groups using ANOVA

Results

The 803 South Asians between ages 44–83 enrolled in the MASALA study were on average five years younger than the MESA study participants. Table 1 shows the baseline characteristics by sex for each of the five racial/ethnic groups. Most South Asians (99%), Chinese (96%) and Latinos (69%) were born outside the U.S. South Asians had significantly higher socioeconomic attainment and lower current smoking rates than each of the MESA groups. South Asians had relatively lower BMI and waist

Discussion

In this cross-sectional comparison between U.S. South Asians and four other U.S. racial/ethnic groups without known cardiovascular disease, we found that South Asian men had similarly elevated prevalence of CAC compared to White men, while South Asian women had lower CAC prevalence than White women but similar to other race/ethnic minority groups in MESA. Mean CAC was similar between South Asian and White men over the age span and after full adjustment for covariates, and South Asian men had

Funding sources

The MASALA study was supported by the NIH grant no.1 R01 HL093009. Data collection at UCSF was also supported by NIH/NCRR UCSF-CTSI Grant Number UL1 RR024131. The MESA study was funded by contracts #N01-HC-95159, N01-HC-95169, N01-HC-95166 from the National Heart, Lung, and Blood Institute.

Disclosures

The authors have no conflicts of interest to disclose.

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