Natural history of abdominal aortic aneurysm: a survey of 63 patients treated nonoperatively

During a 10-year period in which 735 patients presented with abdominal aortic aneurysms to our clinic, 63 were not offered operative treatment. The primary reason for choosing conservative treatment was concomitant diseases that increased the risk of operation. After 2 years of followup, half of the patients died, and the cumulative 5-year survival rate was 15%. Aneurysm rupture was the primary cause of death. The cumulative 5-year mortality hazard rate from rupture was 0.36, corresponding to an annual risk of rupture of 7%. The cumulative 5-year hazard rate of death from all other causes was 1.53, corresponding to an annual risk of 30%. Diameter of the aneurysm was found to be the only factor with a significant impact on the rate of rupture. The cumulative 5-year hazard rate of rupture among patients with aneurysms < 6 cm and > or = 6 cm was 0.2 and 0.6, respectively, corresponding to an annual risk of rupture of less than 5% and 10% to 15%, respectively. However, neither diameter nor other risk factors had significant influence on the time of rupture. In our opinion, once the diagnosis is confirmed the patient should be offered aneurysm resection if the general health status permits anesthesia.