A seasonal variation in the incidence of ruptured abdominal aortic aneurysms

Objective: To discover whether there is a seasonal variation in the incidence of rupture of abdominal aortic aneurysms. Design: Deaths per month due to rupture of abdominal aortic aneurysm were analysed retrospectively using a cosinor regression model. Setting: England and Wales. Subjects: 19599 patients who died from rupture of abdominal aortic aneurysm between January 1991 and December 1995 according to death certification data. Interventions: None. Results: A seasonal variation in the incidence of rupture of abdominal aortic aneurysm occurs, with a peak in winter (p = 0.003). The ratio of rupture of abdominal aortic aneurysm in males and females decreased from more than 12 to 1 below age 60 years to less than 5 to 1 over age 80 years. Conclusions: There is a seasonal variation in the incidence of recorded deaths from abdominal aortic aneurysm in England and Wales, with a peak of deaths in the cold winter months. The underlying cause is unknown, but hypertension and tobacco smoking are predisposing factors to aortic aneurysm rupture. Exposure to tobacco smoke is known to be greater indoors in cold weather and there is a winter peak of blood pressure in hypertensive patients.