Adiposity and the risk of aortic aneurysm: results from the UK Biobank, Japan-Specific Health Check-ups Study and a systematic review and meta-analysis of cohort studies

Overweight and obesity has been associated with increased risk of aortic aneurysm in some cohort studies, however, results have been inconsistent. To clarify this association we analysed data from two large cohort studies with a total of > 1.1 million participants, and conducted a systematic review and meta-analysis of published cohort studies. The analytical cohorts included 495,438 participants in UK Biobank and 630,841 participants in the Japan Specific Health Checkups (J-SHC) Study. Multivariable Cox proportional hazards regression models were used to analyse associations between anthropometric factors and risk of aortic aneurysm. PubMed and Embase databases were searched for studies on adiposity and aortic aneurysm up to 18 March 2026, and random effects models were used to estimate summary relative risks (RRs) and 95% confidence intervals (CIs). In the UK Biobank, a total of 3,447 incident cases and 183 deaths from aortic aneurysm occurred during 12.3 years follow-up, and in the J-SHC Study, 51 aortic aneurysm deaths occurred during 4 years follow-up. In UK Biobank, HRs (95% CIs) were 1.18 (1.08–1.29), 1.51 (1.36–1.67), 1.45 (1.23–1.70), and 1.56 (1.20–2.02) for a BMI of 25-<30, 30-<35, 35-<40, and ≥ 40 vs. 18.5-<25.0, respectively. Positive associations were also observed for the highest vs. lowest quintile of waist circumference (1.66, 1.48–1.87), waist-to-hip ratio (1.67, 1.48–1.89), hip circumference (1.37, 1.22–1.53), waist-to-height ratio (1.70, 1.51–1.91), fat mass (1.62, 1.44–1.83) and body fat percentage (1.45, 1.28–1.63). In the J-SHC Study, comparing the highest vs. lowest categories the HRs were 1.79 (0.86-4.00, p trend =0.15) for BMI, 3.12 (1.10-11.11, p trend =0.006) for waist circumference, and 3.18 (1.17–8.64, p trend =0.01) for waist-to-height ratio. In the meta-analysis, the summary RR per 5 kg/m 2 increment in BMI was 1.17 (1.13–1.21, I 2 = 0%, n = 6 studies) for aortic aneurysm, 1.27 (1.04–1.55, I 2 = 33%, n = 3 studies) for thoracic aortic aneurysm, and 1.11 (1.05–1.17, I 2 = 55%, n = 12 studies) for abdominal aortic aneurysm. The respective summary RRs for total, thoracic, and abdominal aortic aneurysm were 1.29 (0.98–1.68, I 2 = 73%, n = 2), 1.29 (0.92–1.82, I 2 = 67%, n = 2), and 1.15 (1.07–1.24, I 2 = 49%, n = 6) per 10 cm increase in waist circumference, and 1.37 (1.05–1.78, I 2 = 45%, n = 2), 1.47 (0.89–2.42, I 2 = 62%, n = 2), and 1.33 (1.25–1.42, I 2 = 0%, n = 2) per 0.1 unit increase in waist-to-height ratio. These results suggest that higher BMI and abdominal fatness are associated with a dose-related increase in risk of aortic aneurysm overall and across subtypes. Any further studies should further investigate the associations between adiposity measures and subtypes of aortic aneurysm.