Trends in incident acute myocardial infarction in Norway: An updated analysis to 2014 using national data from the CVDNOR project

Background We updated the information on trends of incident acute myocardial infarction in Norway, focusing on whether the observed trends during 2001-2009 continued throughout 2014. Methods All incident (first) acute myocardial infarctions in Norwegian residents age 25 years and older were identified in the Cardiovascular Disease in Norway 1994-2014 project. We analysed overall and age group-specific (25-64 years, 65-84 years and 85 + years) trends by gender using Poisson regression analyses and report the average annual changes in rates with their 95% confidence intervals. Results During 2001-2014, 221,684 incident acute myocardial infarctions (59.4% men) were identified. Hospitalised cases accounted for 79.9% of all incident acute myocardial infarctions. Overall, incident acute myocardial infarction rates declined on average 2.6% per year (incidence rate ratio 0.974, 95% confidence interval 0.972-0.977) in men and 2.8% per year (incidence rate ratio 0.972, 95% confidence interval 0.971-0.974) in women, contributed by declining rates of hospitalisations (1.8% and 1.9% per year in men and women, respectively) and deaths (6.0% and 5.8% per year in men and women, respectively). Declining rates were observed in all three age groups. The overall acute myocardial infarction incidence rates continued to decline from 2009 onwards, with a steeper decline compared to 2001-2009. During 2009-2014, gender-adjusted acute myocardial infarction incidence among adults age 25-44 years declined 5.3% per year, contributed mostly by declines in hospitalisation rates (5.1% per year). Conclusion Acute myocardial infarction incidence rates continued to decline after 2009 in Norway in both men and women. The decline started to involve individuals aged 25-44 years, marking a turning point in the previously reported stagnation of rates during 2001-2009.