Outcomes in a Prospective Cohort of Octogenarian and Nonagenarian Patients Diagnosed With a Small (< 55 Mm) Abdominal Aortic Aneurysm: Rupture, Growth to a Large (>=55 Mm) Size and Mortality Rates

Abstract

Introduction: Due to longer population life expectancy and consistent improvement in diagnostic techniques, there has been a steady increase in the diagnosis of abdominal aortic aneurysms (AAA) in the older population in the last few decades. This tendency is expected to continue and the management of these patients is challenging. We aim to study the natural history of small (< 55 mm) AAA in octogenarian and nonagenarian patients in our health care area to assess the need for follow-up and/or invasive treatment. Methods: We performed a retrospective analysis of a prospective registry of all AAA diagnosed in our health area since 1988, selecting the patients of 80 or more years of age at the time of diagnosis of a small AAA in 1988-2018. We registered clinical and anatomical characteristics of the patients. We divided the patients in 3 groups: 30-39 mm AAA, 40-49 mm and 50-54 mm. The outcome variables were: aortoiliac rupture, AAA growth up to or beyond a surgical size (>=55 mm), and death. We performed a descriptive statistical analysis and compared the three groups, using life tables, Kaplan-Meier curves, uni and multivariate Cox regression. Results: We included 310 patients, 256 (82.6%) men, with mean age of 84.5 years (SD 3.5, range 80-96.3) at the time of diagnosis. The mean follow-up time was 41.6 months (SD 32.8, range 0-140.2). Seventeen (5.5%) AAA ruptured during follow-up; four of these patients were operated on and only one survived. Sixty (19.4%) AAA reached a surgical size; seven were electively repaired, with 0% early mortality. The survival rates for the complete cohort were 80%, 69% y 36% at 1, 2 and 5 years respectively. The rupture rates were 1%, 3% and 7% and the AAA which reached a surgical size were 2%, 5% and 19% for the same time periods. Men and women showed similar rupture rates, expansion rates to a surgical size and late mortality (p>0.05). The patients with 30-39 mm AAA had significantly smaller incidence of rupture (0.127; 95%CI 0.034-0.477; p=0.002) and late mortality rates (0.631; 95%CI 0.420-0.947; p=0.026), and decreased likelihood of reaching a surgical size (0.075; 95%CI 0.035-0.161; p< 0.0001). There were no significant differences between 40-49 mm and 50-54 mm AAA for the rupture and mortality rates (p>0.1), but 40-49 mm AAA were marginally less likely to reach a surgical size (0.581; 95%CI 0.322-1.047; p=0.071). Conclusion: The risk of late rupture of small AAA diagnosed in octogenarian and nonagenarian patients is very small, especially when the AAA is < 40 mm in diameter. In contrast, global mortality is high. Conservative management seems sensible, with strict selection of the patients who would benefit from follow-up and eventual repair. Disclosure: Nothing to disclose