Downward trend in the risk of second myocardial infarction in Sweden, 1987–2007: breakdown by socioeconomic position, gender, and country of birth

Abstract

Second myocardial infarction (SMI) is a significant health problem. There are no nationwide studies on SMI among foreign-born populations that include detailed information about country of birth. Nationwide cohort study of 331,748 men and 186,755 women aged 30-84, living in Sweden, and diagnosed with first myocardial infarction (FMI) between January 1987 and December 2007. Trends in, and risk of, SMI after day 28 of FMI association with gender, educational level, and country of birth were analysed. A hazard ratio (HR) with a 95% confidence interval (CI) yielded a risk estimate of SMI among FMI patients based on the Cox proportional hazard model. Men had a higher risk of SMI than women (HR 1.14, 95% CI 1.12-1.55) with a downward trend over time, regardless of country of birth (p-trend <0.0001). Low educational level increased the HR of SMI irrespective of gender or country of birth. Foreign-born men and women had a slightly increased HR than Sweden-born. Men born in India, Palestine, Uganda, Algeria, and Tunisia and women born in India, Palestine, and Lebanon had approximately a 2-fold risk. Men born in the Netherlands had the lowest risk (HR 0.65, 95% CI 0.44-0.94). Foreign-born who had lived in Sweden for less than 35 years had a higher risk than those that had lived there for 35 years or longer. Although the risk of SMI continued to decrease over time, low socioeconomic position independent of country of birth and gender remained an important risk indicator deserving further attention.