The association between connective tissue laxity and the risk of an abdominal aortic aneurysm

Aims: to investigate whether connective tissue laxity is associated with abdominal aortic aneurysms (AAA). Methods: a nested case control study in a population-based screening programme. The presence of pes planus, scoliosis, pectus deformities, flexible auricular cartilages and Gorling's sign were combined with the Beighton joint mobility score to form a connective tissue laxity score. The association between connective tissue laxity and the risk of AAA was investigated through a logistic regression model. Type III collagen turnover was assessed using a serum radio-immunoassay for type III procollagen (PIIINP). Results: data from 231 controls (aortic diameter <2.5cm) and 190 cases (AAA >2.9 cm) were analysed. Grids ratios (OX), adjusted for known confounders were 3.1 (95% CI: 1.1-8.6)for the highest group of connective tissue scores and 2.4 (95% CI: 1.0-5.4) for the middle group, compared with those with no signs of abnormal connective tissue function. There was no difference in mean collagen turnover between cases and controls, nor between those with a stable AAA >4 cm and those with an expanding AAA. Conclusion: connective tissue laxity is associated with a higher risk of having an AAA. The collagen turnover is similar in subjects with an AAA and controls. Aneurysms may be associated with abnormal connective tissue rather than an increased breakdown of normal collagen.