Meta-Analysis of Seasonal Incidence of Aortic Dissection

We performed the first meta-analysis to identify in which season incidence of aortic dissection is the most and least frequent. MEDLINE and EMBASE were searched through February 2017. Eligible studies were observational studies enrolling patients with aortic dissection and reporting seasonal or monthly incidence of aortic dissection. Study-specific estimates, incidence of aortic dissection in each season (number of aortic dissection in a season divided by that in a year) and risk ratios (RRs) for incidence of aortic dissection in a season versus another season, were combined using the random-effects model. We identified 18 eligible studies enrolling a total of 101,264 patients with aortic dissection. Pooled incidence was 20.6% in summer, 24.8% in autumn, 28.2% in winter, and 25.5% in spring. Pooled analysis demonstrated a statistically significant increase in incidence of aortic dissection in autumn than in summer (RR 1.18; p <0.0001), in winter than in summer (RR 1.37; p <0.0001), in spring than in summer (RR 1.24; p <0.0001), in winter than in spring (RR 1.11; p = 0.006), and in winter than in autumn (RR 1.17; p <0.001); and no statistically significant difference between spring and autumn (RR 1.04; p = 1.00). In conclusion, the incidence in winter (28.2%) was significantly more frequent than that in other seasons and that in summer (20.6%) was significantly less frequent than that in other seasons (winter > spring ≈ autumn > summer).