UCSF Researchers Develop Prediction Model of Aortic Aneurysm

Prediction Model Seeks to Improve Detection of Individuals at Risk for Ascending Aortic Dissection

By Melinda Krigel

Ascending thoracic aortic disease is an important cause of sudden death in the U.S., yet most aortic aneurysms are identified incidentally. To improve assessment of patients who may be at risk for aortic dissection and rupture, researchers from UC San Francisco have developed a prediction model of aortic diameter to identify asymptomatic individuals with enlarged ascending aortic diameter.

In their study, which was published November 15 in the Journal of the American Medical Association (JAMA), the investigators developed and validated a clinical score to estimate ascending aortic diameter. Their prediction model was based on commonly available clinical covariates to identify symptomatic individuals with enlarged ascending aortic diameter, a risk factor for ascending aortic dissection.

The researchers used data from an ongoing magnetic resonance imaging sub-study of the UK Biobank cohort study, which had enrolled participants from 2006 through 2010. Score derivation was performed in 30,018 participants and internal validation in an additional 6,681people. External validation was also performed in 1,367 participants from the Framingham Heart Study (FHS) offspring cohort who had undergone computed tomography from 2002 through 2005, and in 50,768 individuals who had undergone transthoracic echocardiography in the Community Care Cohort Project, a retrospective hospital-based cohort of longitudinal primary care patients in the Mass General Brigham (MGB) network between 2001-2018.

A prediction model was derived in the cohort of 30,018 participants that explained 28.2% to 32.6% of the variance in ascending aortic diameter among the 58,816 participants in the validation cohorts. Correlation between estimated and measured diameter and performance for identifying diameter 4.0 cm or greater were assessed.

“While therapies exist for ascending thoracic aortic aneurysm, full implementation has been limited by the difficulty of identifying at-risk individuals,” said James P. Pirruccello, MD, first author of the study and assistant professor of medicine at UCSF. “Universal imaging would be impractical, so there is interest in identifying features of individuals with ascending aortic enlargement. The objective of the present study was to develop and validate a clinical score to estimate ascending aortic diameter.”

This is the first step of many towards understanding whether we can find at-risk people before they get sick.

James P. Pirruccello, MD

Aortic dissection and rupture are the gravest consequences of thoracic aortic disease, resulting in sudden death with an out-of-hospital mortality rate of 48.6% from 2002 through 2012. Population-based estimates of the incidence of acute aortic dissection have ranged from 4.4 per 100,000 in data collected from 1995 through 2015 in Minnesota to 17.6 in data from 2016 through 2018 in Japan.

While a prediction model based on common clinically available data was derived and validated to predict ascending aortic diameter, the investigators believe further research is needed to optimize the prediction model and to determine whether its use is associated with improved outcomes.

“This is the first step of many towards understanding whether we can find at-risk people before they get sick,” said Pirruccello.