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

We performed a meta-analysis to assess the presence of an annual rhythmic variability of ruptured abdominal aortic aneurysm (RAAA) onset.

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.

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).

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.