A population-based case-control study of the familial risk of abdominal aortic aneurysm

BackgroundSeveral studies have reported a familial clustering of abdominal aortic aneurysm (AAA) supporting that AAA is an inheritable disease, but few population-based studies can be found. Possible gender differences regarding hereditary patterns have been reported.ObjectiveThe aim of this study was to investigate the risk of developing an AAA for first-degree relatives of patients with AAA in Sweden and compare them with matched controls and their relatives.Methods and MaterialsAll persons (3183) born after 1932, diagnosed with AAA between 2001 and 2005, and a random selection of 15,943 age-, gender-, and region-matched controls were included. First-degree relatives of cases and controls were identified via the Multigeneration Register. Family history of AAA for cases and controls was assessed by linking the relatives to the Hospital Discharge Register and Cause of Death Register. The data were analyzed by conditional logistic regression.ResultsThe overall relative risk of AAA associated with family history compared to no family history was 1.9 (95% confidence interval [CI] 1.6-2.2). Comorbidities were more common among the cases than the controls (P < .0001) but the relative risks remained unchanged after adjustment for comorbidities. Stratification for absence or presence of comorbidities showed no significant difference between the two groups (P = .29). The relative risk of AAA for first-degree relatives was similar for women and men (P = .22 for gender differences), ie, the relative risk of AAA was not dependent on the gender of the index person.ConclusionIn this nationwide survey, the relative risk of developing AAA for first-degree relatives to persons diagnosed with AAA was approximately doubled compared to persons with no family history. Neither the gender of the index person nor the first-degree relative influenced the risk of AAA. Several studies have reported a familial clustering of abdominal aortic aneurysm (AAA) supporting that AAA is an inheritable disease, but few population-based studies can be found. Possible gender differences regarding hereditary patterns have been reported. The aim of this study was to investigate the risk of developing an AAA for first-degree relatives of patients with AAA in Sweden and compare them with matched controls and their relatives. All persons (3183) born after 1932, diagnosed with AAA between 2001 and 2005, and a random selection of 15,943 age-, gender-, and region-matched controls were included. First-degree relatives of cases and controls were identified via the Multigeneration Register. Family history of AAA for cases and controls was assessed by linking the relatives to the Hospital Discharge Register and Cause of Death Register. The data were analyzed by conditional logistic regression. The overall relative risk of AAA associated with family history compared to no family history was 1.9 (95% confidence interval [CI] 1.6-2.2). Comorbidities were more common among the cases than the controls (P < .0001) but the relative risks remained unchanged after adjustment for comorbidities. Stratification for absence or presence of comorbidities showed no significant difference between the two groups (P = .29). The relative risk of AAA for first-degree relatives was similar for women and men (P = .22 for gender differences), ie, the relative risk of AAA was not dependent on the gender of the index person. In this nationwide survey, the relative risk of developing AAA for first-degree relatives to persons diagnosed with AAA was approximately doubled compared to persons with no family history. Neither the gender of the index person nor the first-degree relative influenced the risk of AAA.