Gender differences in trends of acute myocardial infarction events: The Northern Sweden MONICA study 1985-2004

Background: The registration of non-fatal and fatal MI events initiated 1985 in the WHO MONICA project has been ongoing in northern Sweden since the end of the WHO project in 1995. The purpose of the present study was to analyze gender differences in first and recurrent events, case fatality and mortality in myocardial infarction (MI) in Northern Sweden during the 20-year period 1985 - 2004. Methods: Diagnosed MI events in subjects aged 25-64 years in the Counties of Norrbotten and Vasterbotten were validated according to the MONICA protocol. The total number of events registered up to January 1, 2005 was 11,763: 9,387 in men and 2,376 in women. Results: The proportion of male/female events has decreased from 5.5:1 to 3:1. For males the reductions were 30% and 70% for first and recurrent MI, respectively, and for women 0% and 40% in the 55-64 year group. For both sexes a 50% reduction in 28-day case fatality was seen in the 25 64 year-group. Mortality was reduced by 69% and 45% in men and women, respectively. Conclusion: First and recurrent events of myocardial infarction was markedly reduced in men over the 20-year observation period, but for women the reduction was seen only for recurrent infarctions. Case fatality, on the other hand, was markedly reduced for both sexes. As a result of the positive effects on incidence and case fatality a substantial reduction was seen in total mortality, most pronounced for men.