Risk of 1st and 2nd composite end-points for the aortic root. Observed risk of the 1st composite end-point (acute type A dissection, rupture and ascending aorta-related death—red dots with their trend line) and the 2nd composite end-point (acute type A dissection, rupture and all cause death—black dots with their trend line) as a function of the sex–age–body surface area-based z score for the aortic root diameter. A hinge point emerges at approximately z score 4. This z score denotes the onset of a steep risk increase, and it is converted to a unique root size for each patient. This patient-specific size can be estimated using equation R (hinge point root = mean + 4 × SD), which plugs in this z score (4) along with the patient-specific, SAS-based mean and SD. The R² for the 1st composite end-point is high, suggesting that this trend line fits nicely into the data. The risk attributed to small roots is overestimated. Given that mid size is not portrayed in this graph, the risk increasing effect of aneurysmal mids interferes and causes a risk surge erroneously attributed to small roots. Moreover, there is a selection bias in small aortas due to the underrepresentation of healthy individuals in any hospital-derived sample.