Grading atherosclerosis in aorta and coronary arteries obtained at autopsy. WHO trials of macroscopic methods.

Many attempts have been made to grade atherosclerosis as found in autopsy material, but the repeatability of the methods used has seldom been tested. Most of the methods used are rough; and, where comparisons are to be made between the data obtained by different observers on different material, it is essential to know whether the differences found are due to the crudity of the method or in fact represent a real difference in the material studied. This paper describes an attempt to obtain comparable data by presenting specially prepared specimens to 14 pathologists from five laboratories in Europe and the Americas. For the purposes of the study, agreed definitions, techniques and criteria were adopted. Intra-observer, intra-laboratory and inter-laboratory disagreement was measured using both transverse- and longitudinal-section procedures. The longitudinally sectioned specimens were examined unstained and subsequently stained for lipid. The results indicate that the longitudinal-section procedure is likely to be useful in discriminating between groups of specimens, provided that certain procedural rules are observed.