Purpose: We present extended follow-up findings of the Kingston prospective sizing program for patients with abdominal aortic aneurysm (AAA) smaller than 5.0 cm in diameter, with gender-specific analysis.
Methods: From 1976 to 2001, 895 patients (688 men, 207 women) with AAA smaller than 5.0 cm were entered, regardless of fitness, in a prospective sizing program in which computed tomography scans were obtained every 6 months. Operations were performed in fit patients with an increase in AAA size to 5 cm (n = 190), AAA expansion greater than 0.5 cm in 6 months (n = 27), or for other reasons (n = 33). Follow-up continued until AAA rupture, surgery, death, or removal from the program.
Results: No AAA smaller than 5.0 cm ruptured during prospective follow-up. There was a statistically significant increase in expansion rate relative to size at entry, with the highest mean expansion rate of 0.52 cm/y for AAA 4.5 to 4.9 cm in diameter. There was no significant difference in AAA expansion rate between men and women. The frequency of surgery was inversely related to age at entry, but was positively related to AAA size at entry, with patients with AAA 4.5 to 4.9 cm at entry 6.8 times more likely (95% confidence interval, 4.3-10.7) to undergo surgery than those with AAA 3.0 to 3.4 cm at entry. Women were older than men at entry, and age at entry in those undergoing surgery was significantly greater in women.
Conclusions: The study confirms the results of the United Kingdom Small Aneurysm Trial and the Aneurysm Detection and Management Study, that is, that risk for rupture is extremely unlikely with AAA smaller than 5.0 cm, which enables safe follow-up surveillance programs in both men and women with AAA smaller than 5.0 cm.