DOPPLER EVALUATION OF RENAL-ARTERY STENOSIS - INTEROBSERVER AGREEMENTIN THE INTERPRETATION OF WAVE-FORM MORPHOLOGY

OBJECTIVE. Analysis of Doppler waveform morphology for features of the tardus-parvus phenomenon has been promoted as a useful and accurate m eans for detecting renal artery stenosis. The purpose of this study wa s to examine and quantify the interobserver agreement of such an analy sis and to determine if interobserver differences limit the value of t his approach for predicting renal artery stenosis. SUBJECTS AND METHOD S. Four observers independently categorized renal artery waveforms of 47 patients (94 kidneys) clinically selected for renovascular hyperten sion. Waveforms were classified into five categories based on the pres ence and severity of tardus-parvus changes in the systolic upstroke an d early systolic peak. This categorization was then compared with angi ographic findings, and the results were analyzed with receiver-operati ng-characteristic curves. Kappa statistics and agreement tables were c omputed to evaluate interobserver agreement. RESULTS. Interobserver ag reement in the waveform analysis for the four interpreters was statist ically significant (p <.001). The receiver-operating-characteristic ar eas produced by the observers indicated, however, that such waveform c lassification was not strongly predictive of renal artery stenosis. CO NCLUSION. We conclude that substantial agreement in the interpretation of waveform morphology can be obtained between independent observers, and that such differences that do exist do not preclude the use of th e pattern-recognition approach to waveform analysis. Even so, the spec ific application of this strategy to the waveform contours of early sy stole was not successful in predicting the presence or severity of ren al artery stenosis.