Association of Thoracic Aortic Aneurysm Size With Long-term Patient Outcomes
Authors: Solomon Matthew D. , Leong Thomas , Sung Sue Hee , Lee Catherine , Allen J. Geoff , Huh Joseph , LaPunzina Paul , Lee Hon , Mason Duncan , Melikian Vicken , Pellegrini Daniel , Scoville David , Sheikh Ahmad Y. , Mendoza Dorinna , Naderi Sahar , Sheridan Ann , Hu Xinge , Cirimele Wendy , Gisslow Anne , Leung Sandy , Padilla Kristine , Bloom Michael , Chung Josh , Topic Adrienne , Vafaei Paniz , Chang Robert , Miller D. Craig , Liang David H. , Go Alan S. ,   Kaiser Permanente Northern California Center for Thoracic Aortic Disease, Chow Norma , Chen Emily , Dawson Katharine , Manace Leslie , Urbania Thomas , Yang Scott , Pompili Mario , Cain Brian , Yano Osvaldo , Hua Hong , Wu Bian , Sharma Guarav , Baker Aaron , Sivamurthy Nayan , Garg Joy , Madriz Thesalia , Hui Honora 
Published: October 2022

ImportanceThe risk of adverse events from ascending thoracic aorta aneurysm (TAA) is poorly understood but drives clinical decision-making.ObjectiveTo evaluate the association of TAA size with outcomes in nonsyndromic patients in a large non–referral-based health care delivery system.Design, Setting, and ParticipantsThe Kaiser Permanente Thoracic Aortic Aneurysm (KP-TAA) cohort study was a retrospective cohort study at Kaiser Permanente Northern California, a fully integrated health care delivery system insuring and providing care for more than 4.5 million persons. Nonsyndromic patients from a regional TAA safety net tracking system were included. Imaging data including maximum TAA size were merged with electronic health record (EHR) and comprehensive death data to obtain demographic characteristics, comorbidities, medications, laboratory values, vital signs, and subsequent outcomes. Unadjusted rates were calculated and the association of TAA size with outcomes was evaluated in multivariable competing risk models that categorized TAA size as a baseline and time-updated variable and accounted for potential confounders. Data were analyzed from January 2018 to August 2021.ExposuresTAA size.Main Outcomes and MeasuresAortic dissection (AD), all-cause death, and elective aortic surgery.ResultsOf 6372 patients with TAA identified between 2000 and 2016 (mean [SD] age, 68.6 [13.0] years; 2050 female individuals [32.2%] and 4322 male individuals [67.8%]), mean (SD) initial TAA size was 4.4 (0.5) cm (828 individuals [13.0% of cohort] had initial TAA size 5.0 cm or larger and 280 [4.4%] 5.5 cm or larger). Rates of AD were low across a mean (SD) 3.7 (2.5) years of follow-up (44 individuals [0.7% of cohort]; incidence 0.22 events per 100 person-years). Larger initial aortic size was associated with higher risk of AD and all-cause death in multivariable models, with an inflection point in risk at 6.0 cm. Estimated adjusted risks of AD within 5 years were 0.3% (95% CI, 0.3-0.7), 0.6% (95% CI, 0.4-1.3), 1.5% (95% CI, 1.2-3.9), 3.6% (95% CI, 1.8-12.8), and 10.5% (95% CI, 2.7-44.3) in patients with TAA size of 4.0 to 4.4 cm, 4.5 to 4.9 cm, 5.0 to 5.4 cm, 5.5 to 5.9 cm, and 6.0 cm or larger, respectively, in time-updated models. Rates of the composite outcome of AD and all-cause death were higher than for AD alone, but a similar inflection point for increased risk was observed at 6.0 cm.Conclusions and RelevanceIn a large sociodemographically diverse cohort of patients with TAA, absolute risk of aortic dissection was low but increased with larger aortic sizes after adjustment for potential confounders and competing risks. Our data support current consensus guidelines recommending prophylactic surgery in nonsyndromic individuals with TAA at a 5.5-cm threshold.