To determine the necessity of permanent monitoring of small aortic aneurysms in the elderly, Mark Rockley, MD, of the Ottawa Hospital and his colleagues investigated the yield of ultrasound surveillance for small abdominal aortic aneurysms (AAAs) in octogenarians, as compared with a younger population. Their goal was to detect the frequency of AAA growth reaching the threshold size for repair. Secondary objectives included analysis of the incidence of AAA repair, and the cost-effectiveness of surveillance.
In Saturday’s Scientific Session 8, Dr. Rockley will report on their retrospective cohort study performed on all patients undergoing AAA surveillance in Ottawa during 2007-2017. The patients were split into two groups by enrollment age (those younger and those equal to or older than 80 years of age) with cross-over to prevent lead-time bias, and stratification by enrollment AAA size.
The two cohorts were cross-referenced with the Ottawa Surgical Database, leveraging the common health region to assure complete data capture, according to Dr. Rockley.
The threshold size for repair was sex specific (women at 5.0cm, men at 5.5 cm) and the factors influencing AAA growth rate were assessed using multiple linear regression. Analyses with Cox proportional hazards and multiple regression models adjusted for sex and enrollment aneurysm size, and cost-effectiveness were analyzed by referencing Ontario billing codes.
The researchers found that 1,231 patients underwent serial ultrasound surveillance, of which 460 (37.4%) were octogenarians at the time of enrollment. Multiple linear regression demonstrated that old age, male sex, and smaller enrollment aneurysm size were significantly protective against AAA growth.
Overall, 355 (28.8%) subjects reached the AAA size threshold for repair, and 313 (25.4%) underwent AAA repair. Octogenarians were half as likely to reach the AAA threshold size for repair when compared with their younger counterparts, and of the 355 subjects whose AAA reached the threshold size for repair, octogenarians were half as likely to undergo elective AAA repair).
Repair of ruptured AAA was rare (0.94%) and age differences were insignificant. The cost of ultrasound surveillance alone to identify one patient who ultimately received elective AAA repair was more than four times more expensive for octogenarians with 3.0-3.9–cm enrollment aneurysms, when compared with the rest of the study sample ($12,080 vs. $2,915, in Canadian dollars, respectively), said Dr. Rockley.
“Our study showed that octogenarians are half as likely as their younger counterparts to experience aortic growth reaching th.e repair threshold size Furthermore, in the event of reaching the size threshold, octogenarians are half as likely to undergo repair, without a significantly increased risk of requiring repair for AAA rupture. In the context of patient-specific factors and wishes, surveillance of AAA less than 4cm in octogenarians is costly and unlikely to be beneficial.” Dr. Rockley concluded.