Abstract 31: Prediction of coronary artery and abdominal aortic calcium in middle-aged adults using the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) risk score: the CARDIA study

Abstract

Background: Risk scores to predict coronary and abdominal atherosclerosis have been developed from autopsy specimens from the right coronary artery and descending aorta and risk factors measured post-mortem in the Pathobiological Determinants of Atherosclerosis in Youth Study (PDAY), cohort aged 15-34 years. While the PDAY risk score predicts coronary artery calcium (CAC) up to 15 years before its assessment in Coronary Artery Risk Development in Young Adults (CARDIA), the clinical validity at 25 years follow up and of the abdominal score to predict abdominal aortic calcium (AAC) has not been tested. Objectives: To test the hypotheses: 1) PDAY risk scores at CARDIA baseline (cohort aged 18-30 years) predict CAC and abdominal aortic calcium (AAC) at year 25 better than PDAY risk scores measured at subsequent time points. 2) Change in risk over time will improve associations in Aim 1. Methods: The CARDIA study assessed CAC and AAC by computed tomography in young adults participating at year 25. The PDAY risk score was calculated from risk factors measured at the CARDIA examinations at years 0 (cohort aged 18-30 years), 5, 10, 15 and 25 (age 43-55 years). Results: Age and gender independent PDAY risk scores increased from CARDIA year 0 to year 25 (coronary from 1.80 to 4.95, abdomen from 1.88 to 3.18). Prevalence of any CAC was 28% and AAC was 53%. For a one point increase in risk score, baseline risk predicted CAC and AAC better than year 25 risk; change in risk improved the prediction further (Table). C-statistics for CAC prediction were higher at year 0 but similar at years 0 and 25 for AAC. Further analyses using PDAY scores calculated at 5 year intervals prior to the CT scan confirmed that CAC at baseline and AAC at year 5 had the highest Odds Ratios for a one point increase in score (AAC year 5 Odds Ratio 1.35 (1.30-1.41)). Conclusions: PDAY risk scores, applied to living adults in the CARDIA study, predicted CAC and AAC in 43-55 year old adults; including change in risk slightly improves model performance.