Leukocyte subsets and abdominal aortic aneurysms detected by screening in men

Objective In the present case–control study, we describe the associations between leukocyte subsets in blood and early, screening‐detected AAA in men. An abdominal aortic aneurysm (AAA) may result in a life‐threatening rupture of the aortic wall. The trigger for AAA formation remains unknown, but the vascular adventitia of advanced AAAs is infiltrated by various leukocytes, indicating that the pathogenesis may involve inflammation. Methods In Sweden, all 65‐year‐old men are invited to an ultrasound examination for detection of AAA. At the Gothenburg screening site, 16 256 men were examined in 2013–2017, 1.2% of whom had an AAA (diameter of the infrarenal aorta ≥30 mm). All men with AAA at screening as well as a randomized selection of AAA‐free screened men were invited to participate in a case–control study. Results The median diameter of AAAs was 33 mm. Men with an AAA (n = 151) had a higher frequency of smoking, hypertension and statin use than controls (n = 224). Blood levels of neutrophils, lymphocytes, monocytes and basophils were higher in individuals with an AAA, but eosinophil count did not differ from controls. Odds ratios (95% confidence interval) for AAA were 8.6 (4.2–17.4), 3.5 (1.9–6.6) and 3.3 (1.8–6.3) for the highest versus lowest quartile of neutrophils, lymphocytes and monocytes, respectively. For neutrophils and lymphocytes, the association with AAA remained significant after adjustment for smoking and other known risk factors/markers. Conclusion Several, but not all, subsets of circulating leukocytes are associated with screening‐detected AAA in men, which is insufficiently explained by associations with smoking and other confounders.