Aortic Stiffness Formula

To the Editor: Aortic stiffness was reported to be a predictor of cardiovascular morbidity and mortality. It was shown that aortic stiffness increases in patients with hypertension, diabetes mellitus, diastolic dysfunction, and coronary artery disease. The aortic stiffness index can be calculated using the following formula: In SBP ⁄ DBP ⁄ AoS AoD ⁄ AoD where SBP is systolic blood pressure, DBP is diastolic blood pressure, AoS is systolic diameter of the ascending aorta, and AoD is the diastolic diameter of the ascending aorta. We read with great enthusiasm the recent study of Protogerou et al, entitled “Pressure Wave Reflections, Central Blood Pressure, and Aortic Stiffness in Patients With Adamantiades-Behçet’s Disease: A Cross-Sectional Case-Control Study Underlining the Role of Chronic Corticosteroid Treatment.” Protogerou et al demonstrated that the augmentation index, but not aortic stiffness, is lower in patients with Adamantiades-Behçet’s disease who take corticosteroids, compared with patients not taking corticosteroids and similar to a control group. They concluded that their results imply a role of inflammation or immunomodulatory mechanisms in the regulation of pressure-wave reflections, and that chronic use of corticosteroids is independently associated with the presence of reduced pressure-wave reflections, but not with aortic stiffness. The formula used by Protogerou et al to calculate aortic stiffness was taken from Ikonomokis et al. There is an erratum in the formula for obtaining aortic stiffness index in this cited article. The formula “Aortic stiffness index ln (SBP/DBP) (AoS AoD)/AoD” should have read, “Aortic stiffness index ln (SBP/ DBP)/(AoS AoD)/AoD.” We think that the authors should reevaluate their findings, because their aortic stiffness index was obtained via an incorrect formula. Using the correct formula to calculate the aortic stiffness index will lead to more accurate and reliable findings.