A meta-analysis of monthly variation in occurrence of abdominal aortic aneurysm rupture

Abstract

Abstract. Background: We performed a meta-analysis to assess the presence of an annual rhythmic variability of ruptured abdominal aortic aneurysm (RAAA) onset. Patients and methods: Eligible studies were observational studies enrolling patients with RAAA and reporting monthly incidence of RAAA. Study-specific estimates, i. e. monthly incidence of RAAA, were combined using the random-effects model. Chronobiological analysis was performed by applying a partial Fourier series to pooled monthly incidence by using the weighted least-squares method. Results: We identified 14 eligible studies enrolling a total of 3,798 patients with RAAA. Pooled monthly incidence of RAAA was 8.7 % in January, 7.7 % in February, 8.7 % in March, 7.3 % in April, 7.8 % in May, 7.2 % in June, 7.0 % in July, 7.0 % in August, 8.1 % in September, 8.8 % in October, 8.4 % in November, and 8.3 % in December. Chronobiological analysis identified a significant (p = 0.0020) annual pattern in the occurrence of RAAA with a peak in December to January and a nadir in June to July. Pooled analysis demonstrated significantly more incidence in December than in June (p = 0.03) as well as in January than in July (p = 0.05). Conclusions: A significant annual pattern in the occurrence of RAAA with a peak in December to January and a nadir in June to July was identified with significantly more incidence in December than in June and in January than in July.