Abdominal aortic aneurysm (AAA), a life-threatening cardiovascular condition, has become one of the substantial burdens of health care today [1]. The global prevalence of AAA is approximately 0.92 %, which rises alongside the population aging trends [2]. In 2017, AAA was estimated to be responsible for about 16,700 deaths worldwide and contributed to 3 million disability-adjusted life years [3]. AAA typically progresses slowly over several years. The early identification of risk factors, combined with proactive interventions, has the potential to mitigate the disease's progression.

Frailty is a common condition among elderly, which is characterized by the progressive decline of multiple physiological systems [4]. It has a strong association with an increased risk of falls, disability, mortality, and some cardiovascular diseases, including arrhythmias and heart failure [[5], [6], [7]]. Notably, frailty may also be related to AAA. Previous studies have reported that the prevalence of frailty among patients with AAA ranges from 2.3 % to 34.6 %, and that frailty significantly heightens the risk of postoperative mortality and complications in patients undergoing AAA surgery [8,9]. However, it remains unclear whether frailty constitutes a risk factor for AAA. In addition, AAA is known to have a strong genetic component. Genome-wide association studies (GWAS) have identified several susceptibility loci linked to AAA and have developed polygenic risk score (PRS) to assess an individual's genetic susceptibility to the disease [10]. Investigating the potential impact of genetic susceptibility on the association between frailty and the risk of AAA is of great interest.

To address this knowledge gap, we investigated the longitudinal relationship between frailty and the long-term risk of AAA within a large-scale cohort from the UK Biobank. Furthermore, we examined potential effect modifiers, including genetic susceptibility, that may influence this association.