Increased risk of thoracic aortic complications among patients with giant cell arteritis: a nationwide, population-based cohort study.

Objective: To assess the risk of aortic aneurysms (AA), aortic dissections (AD) and peripheral arterial disease (PAD) among patients with GCA.

Methods: In this nationwide, population-based cohort study using Danish national health registries, we identified all incident GCA patients ≥50 years between 1996 and 2018 who redeemed three or more prescriptions for prednisolone. Index date was the date of redeeming the third prednisolone prescription. Case definition robustness was checked through sensitivity analysis. We included general population referents matched 1:10 by age, sex and calendar time. Using a pseudo-observation approach, we calculated 5-, 10- and 15-year cumulative incidence proportions (CIP) and relative risks (RR) of AA, AD and PAD with death as a competing risk.

Results: We included 9908 GCA patients and 98 204 referents. The 15-year CIP of thoracic AA, abdominal AA, AD and PAD in the GCA cohort were 1.9% (95% CI 1.5, 2.2), 1.8% (1.4-2.2), 1.0% (0.7-1.2) and 4.8% (4.2-5.3). Compared with the referents, the 15-year RR were 11.2 (7.41-16.9) for thoracic AA, 6.86 (4.13-11.4) for AD, 1.04 (0.83-1.32) for abdominal AA and 1.53 (1.35-1.74) for PAD. Among GCA patients, female sex, age below 70 years and positive temporal artery findings were risk factors for developing thoracic AA. The median time to thoracic AA was 7.5 years (interquartile range 4.4-11.2) with a number needed to be screened of 250 (167-333), 91 (71-111) and 53 (45-67) after 5, 10 and 15 years.

Conclusion: Patients with GCA have a markedly increased risk of developing thoracic AA and AD, but no increased risk of abdominal AA.