Secular trends in incidence and mortality of bacteraemia in a Danish county 1981-1994

We estimated the incidence and mortality of bacteraemia in the County of No rth Jutland and examined factors that could explain the changes observed. A population-based survey of bacteraemia was conducted in the Danish County of North Jutland during 1981-1994. Data were retrieved from a regional bact eraemia register. The mortality was determined through linkage to the Danis h Civil Registration System. A total of 7198 bacteraemias were detected, an d the annual incidence increased from 76 per 100,000 person-years in 1981 t o 153 in 1994. One major determining factor was a change in blood culture s ystem with a higher volume of blood per sample, but annual numbers of blood cultures also increased. The 30-day mortality rate increased from 17 to 40 per 100,000 person-years during the study period, whereas the case-fatalit y rate remained constant (23.6%; 95% confidence intervals 22.6%-24.6%). The number of bacteraemias increased significantly This observation could be e xplained only partly by changes in demography, in blood culture system, and in diagnostic activity. The case fatality rate remained constant despite t he fact that more people were diagnosed with bacteraemia; this indicates th at, with recent blood culture practice, more clinically significant bactera emias are diagnosed.