Stable population-based incidence of acute type A and B aortic dissection.

Background. Aortic dissection (AD) and abdominal aortic aneurysm (AAA) share the same risk factors. Whereas the incidence of AAA is falling, it is unclear whether population-based incidences of acute type A and B AD have changed. The aim of this study was to investigate incidences of AD subtypes over time. Methods. Citizens in the municipality of Malmö, Sweden, diagnosed with AD in 2000-2004 and 2014-2016 were identified through the in-patient, clinical, and forensic autopsy registers. Results. The overall and gender-specific incidences of acute type A and B AD were stable over time. The overall autopsy rate declined from 25.2% in 2000-2004 to 16.1% in 2014-2016 (p = .0001) and patients with acute type A AD were more often encountered at autopsy (78% of cases) during the first time period, compared to 43% of cases during the second time period (p = .005), when the ratio of acute type A: acute type B AD was 2.6: 1. The proportion of individuals <65 years of age tended to be higher in acute type A AD compared to acute type B AD (p = .07). The frequencies of hypertension and smoking were 90% and 91%, respectively, in type A AD, and 86% and 86%, respectively in type B AD. Conclusions. Population-based incidences of acute type A and type B AD were stable over time, but the decreasing autopsy rate has led to a lower proportion of AD diagnosed at autopsy. Primary prevention towards hypertension and smoking seem necessary to reduce AD incidence.