Population-based record linkage study of the incidence of abdominal aortic aneurysm in Western Australia in 1985-1994.

Background: The incidence of abdominal aortic aneurysm (AAA) has increased steadily during the past 30 years.

Methods: Trends in the incidence and surgical intervention for AAA in Western Australia were reviewed for the interval 1985-1994. A population-based health database was used to link morbidity and mortality records of all patients aged 55 years or more who died from rupture or were admitted and treated surgically for AAA. Three groups were separated for analysis: patients with a ruptured AAA, those admitted for elective repair and those admitted as an emergency with an acute (non-ruptured) aneurysm.

Results: There was a decline in the incidence of both emergency and elective procedures for AAA after 1992. While the mortality rate from ruptured AAA has also fallen since 1991, the overall case fatality rate for ruptured AAA has fallen by only 1.3 per cent (from 80.7 to 79.3 per cent).

Conclusion: The decline in mortality rate and emergency procedures may result from a fall in the incidence of ruptured AAA, due to an increasing rate of elective surgery before 1992. The decline in elective procedures from 1992 may be due to a fall in the prevalence of AAA owing to high rates of elective surgery, or to a fall in the incidence of the disease itself.