GRADING ATHEROSCLEROSIS IN AORTA AND CORONARY ARTERIES OBTAINED AT AUTOPSY: APPLICATION OF A TESTED METHOD.

A method of assessing "atherosclerosis", if used according to certain rules, was shown in an earlier study to be capable of discriminating between groups of aortas or coronary arteries according to the quantity of certain defined lesions. It would not measure absolute amounts, but would show whether one group of specimens had more or less of the factor assessed than another and would indicate the statistical significance of this finding according to the number of specimens in each group.The method has now been applied to a study of material from six communities in three countries.This paper outlines how the rules of procedure were applied. Intra-observer and inter-observer calibration tests carried out in a routine manner during four "grading sessions" and inter-sessional tests are described.The discriminatory power in comparing groups of specimens from nearly 3000 subjects is calculated and shown according to artery (thoracic aorta, descending aorta, right coronary, left anterior descending coronary, left circumflex coronary) and type of lesion ("total amount of atherosclerosis", "fatty streak", "fibrous plaque", "complicated lesion" and "calcification"). Observations on "coronary stenosis" were also made. The discriminatory power of the method was calculated for this factor and, contrary to many expectations, was found to be of practical value.Definitions and general procedure are described in annexes.