Abstract 13418: Inter-relation of Parity and Coronary Artery Calcium With Cardiovascular Disease Events: The Multi-ethnic Study of Atherosclerosis

Introduction: Coronary artery calcium (CAC) is a measure of subclinical atherosclerosis and predicts cardiovascular disease (CVD) events. Greater parity, or number of live births, has been shown to relate to CVD. We examined whether the relation of parity to CVD events may depend on the presence and extent of subclinical atherosclerosis measured by CAC. Methods: We studied 3151 women free of CVD at baseline in the Multi-Ethnic Study of Atherosclerosis, a prospective study of CVD. Participants were stratified by parity categories of 0-1 (reference), 2-3, and ≥4 and by baseline CAC categories of 0, 1-99, and 100+. We compared the incidence of CVD (myocardial infarction, stroke, resuscitated cardiac arrest, and coronary heart disease deaths) per 1000 years based on parity across levels of CAC over 13 years. Cox regression determined the joint association of parity and CAC on the incidence of CVD. Results: Women with greater parity had a higher prevalence of any CAC and CAC≥100 (p<0.01); among those with CAC, parity related to greater mean CAC scores (175, 184, and 284, respectively) (p<0.01). Women with greater parity also had greater incident CVD (7.1%, 8.7%, and 11.3% for 0-1, 2-3, and ≥4 live births, respectively, p-trend =0.01) and extent of CAC directly related to the incidence of CVD within parity groups. However, the association of parity with CAC was attenuated after adjustment for age, race, income, smoking and other risk factors. Parity also directly related to the incidence of CVD within CAC categories ( Figure ); however, from Cox regression analyses, these relations were attenuated when adjusted for age, ethnicity and other risk factors. Conclusion: In unadjusted analyses, we show parity to be associated with the prevalence of any or significant CAC, extent of CAC among those with CAC>0, as well as the incidence of CVD events, overall and according to the presence and extent of CAC. However, the association of parity with CVD risk was attenuated after adjustment for other factors.