Comment on Tynjälä et al. Arterial Stiffness Predicts Mortality in Individuals With Type 1 Diabetes. Diabetes Care 2020;43:2266-2271

Tynjälä et al. (1) reported that an increase in augmentation index (AIx), a measure of arterial stiffness, is independently associated with all-cause mortality and a composite end point of cardiovascular and/or diabetes-related cause of death in a prospective cohort of patients with type 1 diabetes (T1D). They concluded that AIx predicts both all-cause mortality and the composite end point of cardiovascular and/or diabetes-related death in T1D and suggested that it might be a useful tool for predicting cardiovascular risk in patients with T1D and, therefore, helpful to their clinical management. However, they did not attempt to build an AIx-based predictive model to produce a future risk estimate.

Cardiovascular disease is the leading cause of death in T1D, and simple models are urgently needed to guide its prediction in routine clinical practice. Current models for predicting cardiovascular risk in T1D have not gained wide acceptance, likely because they include too many factors (2,3). Risk scores are usually compared with the C-statistic, which quantifies the probability that a randomly selected patient who experienced a cardiovascular event had a higher risk score than a patient who had not experienced the event, and ranges from 0.5 (random prediction) to 1.0 (perfect prediction). The model with the higher C-statistic—the Steno Type 1 Risk Engine (ST1RE) (3)—includes 10 factors (age, sex, smoking, exercise, diabetes duration, systolic blood pressure, LDL cholesterol, HbA_1c, estimated glomerular filtration rate [Chronic Kidney Disease Epidemiology Collaboration equation], and micro/macroalbuminuria) and classifies patients with T1D and no previous cardiovascular disease according to their 5- and 10-year cardiovascular risk into low (<10%), moderate (10–20%), and high (≥20%) risk; its C-statistic is 0.83 (95% CI 0.81–0.85) for 5-year prediction and 0.82 (95% CI 0.80–0.83) for 10-year prediction (3). In a cross-sectional cohort of 179 patients with T1D, we used the ST1RE (10-year risk) to classify patients into three risk levels: 105 with low risk, 53 with moderate risk, and 21 with high risk (4). We reported two cutoffs of aortic pulse velocity (aPWV) (the gold standard for measuring arterial stiffness), with potential relevance for routine clinical practice due to their high C-statistics for 10-year prediction: aPWV >7.3 m/s for moderate/high risk (C-statistic 0.91, 95% CI 0.87–0.95) and aPWV >8.7 m/s for high-risk (C-statistic 0.88, 95% CI 0.81–0.95). We recognize that these cutoffs need to be validated in larger prospective cohorts of patients with T1D.

Arterial stiffness integrates the deleterious effect of any factor (known or unknown) on the vascular wall along the entire life of the individual (5). That most (if not all) factors included in the ST1RE increase arterial stiffness is a compelling rationale for using arterial stiffness to simplify the assessment of cardiovascular risk in T1D. Accordingly, we believe that it would be of great interest if Tynjälä et al. could provide data for the cutoff values of AIx in their prospective study, to confirm their suggestion of AIx as a useful tool for cardiovascular risk prediction in patients with T1D in routine clinical settings, which would be an important step in guiding their clinical management.

• © 2021 by the American Diabetes Association