Studies show that both incidence and mortality in acute myocardial infarction are declining. It was expected that introduction of the troponin biomarkers in 2000 would lead to an increase in the number of diagnosed myocardial infarctions. We aimed at establishing how introduction of troponin and the fact that elderly comprise an increasing part of the population with an inherent increased risk for myocardial infarction, affected myocardial infarctions in our region with respect to incidence, age distribution and mortality.
Material and methods.
All patients admitted to our hospital with a diagnosis of acute myocardial infarction (ICD 9 and 10) from 1990 to 2005 were included in the study. Data were imported from our electronic journal system with a database tool (Qlikview). Information about the incidence of myocardial infarction in all of Norway was taken from The Norwegian Inpatient Registry and population data were taken from Statistics Norway. Data were transferred from Qlikview to Excel and SPSS for statistical analysis.
The incidence of myocardial infarction varied from year to year in our hospital area; it increased from 2000, but then decreased during the last two years. The proportion of patients aged 80 and older increased from 13 to 36 % (p < 0.0001) in our hospital during the 15 years. One-year mortality declined for the following age groups from 1990 to 2004; 0 – 59 years (p = 0.0005), 60 – 69 years (p = 0.009) and 70 – 79 years (p = 0.003). This decline was not seen in the age group of 80 years and older (p = 0.66). In 2003, one-year mortality in these four age groups was 3, 15, 23 and 45 % respectively.
The incidence of myocardial infarction increased in our hospital after the introduction of troponin in 2000; but decreased the last two years of the study in our area, but not in Norway in general. The proportion of patients from 80 years and older increased more than what the general increase in the population would warrant. Mortality decreased in all age groups over the 15-year period, except for those aged 80 years and older.
Anders Hovland, Hanne Bjørnstad, Oddgeir Strømsnes, Erik Waage-Nielsen, Joe Sexton Om forfatterne