Introduction Cardiovascular mortality has declined rapidly in recent decades in many developed countries. Although determinants of these trends have been investigated in ecological studies, little evidence has so far been available from individual participant data.
Methods The Million Women Study is a prospective cohort study of approximately 1.3 million women from England and Scotland, recruited in 1996–2001. For women 50–69 years of age, trends in mortality due to cardiovascular causes (International Classification of Diseases, version 10: I00–I99) were examined in age-period-cohort analyses of individual participant data, linked to death registrations. The first 4 years of follow-up for each woman were excluded to account for an initial healthy cohort effect.
Results After exclusion of the first 4 years of follow-up, a total of 8349 cardiovascular deaths occurred in women aged 50–69 years during 2000–2009. In this period, the there was a 5% (95% CI 4 to 6%) overall annual reduction in cardiovascular mortality. Baseline body mass index, smoking status, alcohol consumption, socioeconomic status and geographical region were each strongly associated with cardiovascular mortality in multivariate models (p <0.001), as expected. However, there was no strong evidence of differing trends in cardiovascular mortality across levels of these risk factors, consistent with little interaction between the risk factors and time trends in cardiovascular mortality.
Conclusion In this cohort of women from England and Scotland, the recent secular decline in cardiovascular mortality was evident both in high and in low cardiovascular risk individuals, according to several lifestyle and socioeconomic risk factors.