Regional variation in the incidence of abdominal aortic aneurysm in Sweden

The risk factor profile is similar between patients with abdominal aortic aneurysm (AAA) and coronary heart disease (CHD). CHD is more common in the north of Sweden. It is unknown whether similar regional differences in the incidence of AAA exist. The aims of this study were to investigate whether there is a regional gradient of AAA incidence, and to compare time trends and the frequency of interventions between regions.

Swedish citizens have a 12-digit personal identification number. The Swedish Hospital Discharge Register covers inpatient care (diagnosis, admission, procedure codes, sex, date of birth, county). Population size was obtained from the central statistical bureau. Regions were south, mid and north.

All records for 1990-2005 were extracted and 35 418 individuals with AAA were identified (74.8 per cent men). The highest age-standardized incidence (102.7 per 100,000) was found in men in the north region. The age-adjusted incidence ratio for men in the north region compared with the south was 1.38 (95 per cent confidence interval 1.34 to 1.42). Similar differences were found in women: incidence ratio for north compared with south region 1.39 (1.07 to 1.81). The proportion treated was larger in men and varied by region: 46.9 per cent of men in the mid region compared with 43.7 per cent in the south received treatment (P < 0.001), whereas 29.8 per cent of women in the north region versus 25.4 per cent in the south had an intervention (P = 0.001). The incidence did not increase over time.

The higher incidence of AAA in the north of Sweden corresponds well with reported CHD patterns. The incidence of AAA in the population did not increase significantly over time, in contrast to the increasing intervention rates.