Nationwide mortality following acute type B aortic dissection and the survival advantage of obesity among dialysis patients in Japan.

Background: The incidence of acute type B aortic dissection is higher than that of acute type A aortic dissection among patients on dialysis. However, the impact of being on chronic dialysis on outcomes after type B aortic dissection remains unknown. This study aimed to investigate the trends in in-hospital mortality after type B aortic dissection and the association between body mass index (BMI) and survival paradox on dialysis.

Methods: This study included 48,889 type B aortic dissection hospitalizations in Japan from 2010 to 2020 based on data from a nationwide administrative database. Logistic regression was used to examine mortality risks and restricted cubic spline to investigate the non-linear association between mortality and BMI.

Results: There were 2,116 in-hospital deaths, and the mortality rates were 8.0% in patients receiving chronic dialysis and 4.3% in patients not receiving dialysis. Patients not receiving dialysis had decreased trends of absolute mortality. Meanwhile, patients receiving chronic dialysis had a higher mortality rate from 2010 to 2020. The mortality risk was high in patients receiving chronic dialysis who were underweight and had normal BMI, but not in those who were overweight. Restricted cubic spline analysis showed that a higher BMI was associated with a lower mortality risk in dialysis patients. This finding contrasted the U-shape observed in patients not receiving dialysis.

Conclusions: A lower BMI was associated with a higher risk of in-hospital mortality after type B aortic dissection among dialysis patients, thereby illustrating the obesity paradox. Our findings provide insights that can enhance the management strategies for dialysis patients facing type B aortic dissection.