title: Racial Differences in the Performance of Existing Risk Prediction Models for Incident Type 2 Diabetes: The CARDIA Study.
abstract: OBJECTIVE
  In 2010, the American Diabetes Association (ADA) added hemoglobin A1c (A1C) to the guidelines for diagnosing type 2 diabetes. However, existing models for predicting diabetes risk were developed prior to the widespread adoption of A1C. Thus, it remains unknown how well existing diabetes risk prediction models predict incident diabetes defined according to the ADA 2010 guidelines. Accordingly, we examined the performance of an existing diabetes prediction model applied to a cohort of African American (AA) and white adults from the Coronary Artery Risk Development Study in Young Adults (CARDIA).
  
  
  METHODS
  We evaluated the performance of the Atherosclerosis Risk in Communities (ARIC) diabetes risk prediction model among 2,456 participants in CARDIA free of diabetes at the 2005-2006 exam and followed for 5 years. We evaluated model discrimination, calibration, and integrated discrimination improvement with incident diabetes defined by ADA 2010 guidelines before and after adding baseline A1C to the prediction model.
  
  
  RESULTS
  In the overall cohort, re-estimating the ARIC model in the CARDIA cohort resulted in good discrimination for the prediction of 5-year diabetes risk (area under the curve [AUC] 0.841). Adding baseline A1C as a predictor improved discrimination (AUC 0.841 vs. 0.863, P = 0.03). In race-stratified analyses, model discrimination was significantly higher in whites than AA (AUC AA 0.816 vs. whites 0.902; P = 0.008).
  
  
  CONCLUSIONS
  Addition of A1C to the ARIC diabetes risk prediction model improved performance overall and in racial subgroups. However, for all models examined, discrimination was better in whites than AA. Additional studies are needed to further improve diabetes risk prediction among AA.
authors.affiliation: Department of Epidemiology, School of Public Health, Brown University, Providence, RI Center of Innovation in Long-Term Services and Supports, Providence Veterans Affairs Medical Center, Providence, RI mary_lacy@brown.edu.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Lacy
authors.affiliation: Department of Epidemiology, School of Public Health, Brown University, Providence, RI.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Wellenius
authors.affiliation: Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: Mercedes R
authors.initials: MR
authors.lastname: Carnethon
authors.affiliation: Department of Epidemiology, School of Public Health, Brown University, Providence, RI.
authors.forename: Eric B
authors.initials: EB
authors.lastname: Loucks
authors.affiliation: Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: April P
authors.initials: AP
authors.lastname: Carson
authors.affiliation: Department of Biostatistics, School of Public Health, Brown University, Providence, RI.
authors.forename: Xi
authors.initials: X
authors.lastname: Luo
authors.affiliation: Department of Qualitative Health Sciences, University of Massachusetts Medical School, Worcester, MA.
authors.forename: Catarina I
authors.initials: CI
authors.lastname: Kiefe
authors.affiliation: Department of Epidemiology, School of Public Health, Brown University, Providence, RI.
authors.forename: Annie
authors.initials: A
authors.lastname: Gjelsvik
authors.affiliation: Cardiovascular and Metabolic Conditions Section, Division of Research, Kaiser Permanente Northern California, Oakland, CA.
authors.forename: Erica P
authors.initials: EP
authors.lastname: Gunderson
authors.affiliation: Department of Epidemiology, School of Public Health, Brown University, Providence, RI.
authors.forename: Charles B
authors.initials: CB
authors.lastname: Eaton
authors.affiliation: Department of Epidemiology, School of Public Health, Brown University, Providence, RI Center of Innovation in Long-Term Services and Supports, Providence Veterans Affairs Medical Center, Providence, RI Division of Cardiology, Providence Veterans Affairs Medical Center, Providence, RI.
authors.forename: Wen-Chih
authors.initials: WC
authors.lastname: Wu
mesh_terms: D000328:Adult; D001741:Black or African American; D019540:Area Under Curve; D050197:Atherosclerosis; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000208:ethnology*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D044465:White People; D055815:Young Adult
chemical_list: D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human