COMPARISON OF CENTRALIZED VERSUS SITE-BASED MEASUREMENT OF ANGIOGRAPHIC STENOSIS FOR ELIGIBILITY IN THE ASYMPTOMATIC CAROTID ATHEROSCLEROSIS STUDY

RATIONALE AND OBJECTIVES. The authors determine the reliability of cen tralized versus noncentralized (site-based) measurement of angiographi c stenosis of patients enrolled into the multicenter, prospective, Asy mptomatic Carotid Atherosclerosis Study by angiographic studies, METHO DS. Percent agreements and correlations of 244 masked and prospectivel y interpreted angiograms were calculated for comparison of centralized and noncentralized readers measuring the percent carotid stenosis fro m the same angiographic studies, Univariate summary statistics for dif ferences in percent stenoses were calculated for these readings, RESUL TS. Agreement between readings were 88.5% and 91.8% with kappa statist ics of 0.77 and 0.73 for greater than or equal to 60% and greater than or equal to 80% stenosis, respectively, for comparison of 33 centers to the designated central reader, Comparison between the designated ce ntral reader and a second central reader derived percent agreements of 85.0% and 86.5% with kappa statistics of 0.69 and 0.41 for greater th an or equal to 60% and greater than or equal to 80% stenoses, respecti vely, for arteries selected from the original group, Hence, agreement was slightly better between the enrolling centers and the designated c entral reader than between the two central readers, CONCLUSIONS. Both centralized and noncentralized (site-based) methods of angiographic me asurement of stenosis are equally reliable for large, prospective, mas ked, multicenter trials when quality control measures are instituted t o ensure uniform application of eligibility criteria.