Reproductive factors and risk of ischaemic heart disease in women: a case control study

Abstract

Coronary artery disease is the leading cause of mortality among both men and women worldwide but attention given to ischaemic heart disease (IHD) among women is not as much as for men. In this study, the risk factors of IHD among women were explored but the main focus was on pre-pregnancy, pregnancy and post-pregnancy risk factors experienced by women. Determination of risk factors was through case control study conducted among 142 newly diagnosed IHD female patients aged between 30-65 years old registered in all government hospitals in Terengganu. They were frequency matched with 142 population controls from similar age group. Data was collected through face to face interview as well as through self-administered inventories of self-developed and adapted questionnaires, physical examination and extraction of information from records. The data obtained were the sociodemographic and socioeconomic profile, co-morbidities and reproductive history, physical activities (IPAQ-M), dietary fat intake (Short Fat Questionnaire), stress (GHQ-12), exposure to environmental tobacco smoke (modified ETS measured through GATS), anthropometric measurements (physical examination) and biochemical markers (records). Results of analysis showed that the respondents were mostly Malays and comparable in age (mean age of cases and controls of 52.56 (sd=8.65) and 52.27 (sd=8.96) respectively). Crude analysis of traditional risk factors showed that diabetes mellitus, hypertension, waist circumference, HDL-cholesterol level, family history of IHD and ETS exposure were significant risk factors while reproductive factors namely age at first delivery, parity, having positive history of miscarriage, stillbirth, giving birth to LBW babies as well as breastfeeding duration were significant risk factors of IHD. However the final model using hierarchical logistics regression analysis found that women with history of exposure to environmental tobacco smoke (ETS) were at higher odds of getting IHD (OR=3.00, 95% confidence interval (CI)=1.74-5.11) compared to women who had no such history. Women with low HDL-cholesterol (HDL-C) had similar odds of IHD compared to those with high HDL-C if they had positive family history of IHD (OR=1.22, 95% CI=0.30-4.87) but they had significantly higher odds (OR=9.39, 95% CI=2.25,39.14) if they had no family history of IHD. Reproductive factors that played important roles in contributing to risk of IHD were history of Gestational Diabetes Mellitus (GDM) (OR=3.39, 95% CI=1.35-8.51) and also age at first birth. The risk of IHD in later life is lowered by 27% for every 5 years increase in age at first birth (OR=0.94, 95% CI=0.88-0.99). These findings contribute to knowledge on reproductive risk factors of IHD among women in Malaysia and the information can be useful to policy makers and public health staff in planning early preventive programmes for women. Keywords: case control, ischemic heart disease, women, reproductive risk factors, Malaysia.