1. Carotid Intima-Media Thickness (CIMT): A Reproducibility Study Mindy Columbus, Brian Wagner, Emma Barinas-Mitchell Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260  Coronary heart disease is the leading cause of death in America today, and caused 869,724 deaths in 2004.  Coronary heart disease is caused by atherosclerosis, the narrowing of coronary arteries due to fatty build ups of plaque.  CIMT is a well established surrogate marker of atherosclerosis and a predictor of cardiovascular disease events.  CIMT is a valid and reproducible measure of subclinical cardiovascular disease. www.nhlbi.nih.gov  The Ultrasound Research Lab (URL) in the Department of Epidemiology performs subclinical cardiovascular disease testing for many NIH funded population-based studies.  Digitized images are captured in real time using transverse and longitudinal views of the near and far walls of the distal CCA and the far wall of the bulb and ICA.  CIMT is calculated as the average of the intima media thickness layers across the 8 segments to obtain the mean average CIMT. Introduction References 1.Chambless, L. et al. Risk Factors for Progression of Common Carotid Atherosclerosis: The Atherosclerosis Risk in Communities Study, 1987- 1998. American Journal of EpidemiologyAmerican Journal of Epidemiology. 2002;155:38-47. 2.de Groot E. et al. Measurement of carotid intima- media thickness to assess progression and regression of atherosclerosis. Natural Clinical Practice. Cardiovascular Medicine. 2008 May;5(5):280-8. 3.Sekikawa A. et al. Less Subclinical Atherosclerosis in Japanese Men in Japan than in White Men in the United States in the Post-World War II Birth Cohort. American Journal of Epidemiology. 2007;165:617-624. 4.Sutton-Tyrrell, K. et al. Measurement Variability in Duplex Scan Assessment of Carotid Atherosclerosis. Stroke. 1992, 23:215-220. 5.Thompson, T., Sutton-Tyrrell, K., Wildman, R. 2001. Continuous Quality Assessment Programs Can Improve Carotid Duplex Scan Quality. The Journal of Vascular Technology 25(1):33-39. Results Methods Summary of Training:  Carotid duplex scanning  Reading carotid scans  Certification in reading of scans  Reading for reproducibility study Study Design:  Volunteers recruited for carotid duplex scanning  Tech 1 = Certified URL sonographer  Tech 2 = Mindy Columbus Study Population:  N=20  Females = 17 (85%)  Males = 3 (15%)  Age Range = 24 – 77 years Hypothesis The null hypothesis is that there is no difference in CIMT between the Toshiba and Antares Doppler ultrasound machines. Question In the Department of Epidemiology Ultrasound Research Lab (URL), participants of the ERA JUMP study are returning for a five year follow-up visit for CIMT measurements to determine progression rates of subclinical atherosclerosis.A Toshiba 140A Doppler ultrasound scanner was used for the baseline measurements, and the question is whether the follow-up measurements can be taken on a Siemens Sonoline® Antares Doppler ultrasound scanner in order to predict progression and not to introduce error due to differences in machines.. Mean Difference = -0.045 Mean absolute difference = 0.052 Standard Deviation = 0.063 Range = -0.256 to 0.077 Spearman correlation (r=0.93, p<.0001) ICC = (0.02534/0.0282651 = 0.896) Conclusion A five year mean CIMT progression rate of ~0.04 mm was estimated based on the literature 1. Since the mean absolute difference was 0.052 mm a difference in progression may be difficult to detect, and may in fact appear that the participant’s mean CIMT has improved. There was a difference between the machines, and a presence of systematic bias illustrated thicker CIMT reads with the Toshiba machine. This is likely due to the fact that the Antares scanner produces a crisper and clearer image demonstrating advancement of newer digitial technology. Based on these results, we conclude that the implementation of newer ultrasound technology may adversely affect the validity of progression data for follow-up studies that utilized the older technology for baseline measurements of CIMT. Acknowledgements We would like to thank the staff of the Department of Epidemiology Ultrasound Research Lab for the training and resources used to conduct this study. Siemens Sonoline® Antares Toshiba 140A Statistical Analyses: Intraclass correlation (ICC) is an estimate of the degree of total measurement variability caused by between individual variation. Certification Reads – Tech 1 vs. Tech 2 Mean Difference = 0.015 Mean absolute difference = 0.022 Standard Deviation = 0.024 Range = -0.022 to 0.049 Spearman correlation (r=0.98, p<.0001) ICC = (0.02549/0.0257512 =.99) Antares vs. Toshiba Reads *mavga = average CIMT Antares, *mavgt = average CIMT Toshiba, *dmavgat = difference of average CIMT between Antares and Toshiba  There is a presence of systematic bias in the statistics for the Antares vs. Toshiba comparison depicting thicker reads of CIMT with the Toshiba than with the Antares. 20 Volunteers Antares Tech 1 (scan) Antares Tech 1 (scan) Toshiba Tech 1 (read) Toshiba Tech 1 (read) Toshiba Tech 1 (scan) Toshiba Tech 1 (scan) Toshiba Tech 2 (read) Toshiba Tech 2 (read) Antares Tech 1 (read) Antares Tech 1 (read) Antares Tech 2 (read) Antares Tech 2 (read) obsurlidmavgamavgtdmavgat 1702370.574440.83000-0.25556 2702560.688440.83469-0.14625 39012060.677560.73613-0.05856 4701360.622190.67969-0.05750 59010170.891310.94500-0.05369 69011360.600000.65069-0.05069 7700470.563690.61381-0.05012 8702230.552940.60088-0.04794 99012050.488750.53581-0.04706 109012080.523130.55294-0.02981 11702080.621380.64950-0.02812 129010690.635060.66281-0.02775 13710250.553500.58038-0.02687 14701050.765750.79213-0.02638 159012090.490690.51500-0.02431 169011220.495750.51600-0.02025 17700430.968310.98056-0.01225 18701480.866690.87731-0.01062 19710621.030381.03925-0.00887 209011250.905310.828630.07669