Growth Rates of Small Abdominal Aortic Aneurysms Identified in a Contemporary Practice

Abstract

In December 2019, the U.S. Preventive Task Force recommended, with moderate benefit, 1ne-time screening for abdominal aortic aneurysms (AAAs) in men aged 65 to 75 years with a positive smoking history. The U.S. Preventive Task Force suggested research to evaluate rescreening benefits for persons with negative screening results for a 5.5-cm AAA and the timing of additional imaging studies. The purpose of the present study was to evaluate the natural history of AAAs identified during a 10-year period to outline the follow-up surveillance intervals for detected AAAs. A cohort observational study of all patients screened for AAA from January 1, 2007 to December 31, 2016, within a regional health care system was conducted. AAA was defined as an aortic diameter of ≥3 cm. Clinical data, AAA size, interval from screening to repair, and mortality rates were recorded. All data were analyzed through December 31, 2019. A total of 1196 patients (age, 76.3 ± 6.8 years) had had AAAs detected from screening. The average follow-up period was 6.5 ± 3.3 years from date of screening to the end of the analysis or the date of death. The average interval from AAA screening to repair was 34.1 ± 33.9 months (Fig). A total of 204 AAA repairs were performed on patients identified through screening, including 178 endovascular aneurysm repairs (87%) and 26 open repairs (13%), within the analysis period. Stratified by the initial screened aortic diameter, the median interval from screening to repair was as follows: diameter, 3.0 to 3.4 cm: 6.2 years (95% confidence interval [CI], 5.9-6.4); diameter, 3.5 to 3.9 cm: 5.3 years (95% CI, 4.9-5.7); diameter, 4.0 to 4.4 cm: 3.2 years (95% CI, 2.8-3.5); diameter, 4.5 to 4.9 cm: 2.7 years (95% CI, 2.2-3.2); diameter, 5.0 to 5.4 cm: 0.9 year (95% CI, 0.6-1.2); and diameter, ≥5.5 cm: 0.2 year (95% CI, 0.1-0.2). Each patient had undergone an average 1.6 ± 2.4 ultrasound scans and 0.9 ± 1.5 computed tomography scans for AAA surveillance (Table). Of the 1196 patients, 468 had died (39%) and 9 possible ruptures had occurred during the follow-up period. These possible ruptures had occurred in patients who had refused repair or were too high risk to undergo repair. After the initial AAA diagnosis, we recommend the following surveillance intervals for AAA with a diameter of 3.0 to 5.4 cm until repair: 3.0- to 3.9-cm diameter, every 5 years; 4.0- to 4.4-cm diameter, every 3 years; 4.5- to 4.9-cm diameter, every 2 years, and 5.0- to 5.4-cm diameter, every 6 months. No undiagnosed AAA ruptures were identified during the follow-up period.TableClinical summaryVariableAAA diameter, cmAll (N = 1196)3.0-3.4 (n = 657)3.5-3.9 (n = 231)4.0-4.4 (n = 112)4.5-4.9 (n = 79)5.0-5.4 (n = 56)≥5.5 (n = 61)Age, years75.6 ± 6.677.5 ± 6.876.4 ± 6.878.9 ± 8.175.7 ± 6.376.2 ± 6.676.3 ± 6.8Follow-up length, years6.7 ± 3.16.8 ± 3.36.0 ± 3.66.0 ± 3.36.0 ± 3.45.5 ± 3.56.5 ± 3.3Follow-up ultrasound scans (n = 1948)1.4 ± 2.22.6 ± 2.92.3 ± 2.61.7 ± 1.80.7 ± 1.30.1 ± 0.41.6 ± 2.4Follow-up CT scans (n = 1075)0.7 ± 1.31.1 ± 2.01.2 ± 1.61.3 ± 1.61.4 ± 1.41.0 ± 1.10.9 ± 1.5Interval from screening to repair, months67.6 ± 38.663.8 ± 37.739.7 ± 22.037.6 ± 23.618.2 ± 17.14.8 ± 10.134.1 ± 33.9Interval from screening to repair, years5.6 ± 3.25.2 ± 3.13.3 ± 1.83.1 ± 1.91.5 ± 1.40.4 ± 0.82.8 ± 2.8AAA repairs, total No. (%)35 (5.3)21 (9.1)27 (24.1)33 (41.8)42 (75.0)46 (75.4)204 (17.1) EVAR31 (88.6)20 (95.2)22 (81.5)28 (84.4)40 (95.2)37 (80.4)178 (87.3) Open4 (11.4)1 (4.8)5 (18.5)5 (15.2)2 (4.8)9 (19.6)26 (12.7)Patients who died187 (28.5)100 (43.3)61 (54.5)53 (67.1)31 (55.4)36 (59.0)468 (39.1)AAA, Abdominal aortic aneurysm; CT, computed tomography; EVAR, endovascular aneurysm repair.Data presented as mean ± standard deviation or number (%). Open table in a new tab