THE SIMPLIFIED CAPTOPRIL TEST - AN EFFECTIVE TOOL TO DIAGNOSE RENOVASCULAR HYPERTENSION

There is much variability among reports of the accuracy of the captopr il test for renovascular hypertension. Factors that contribute to this variability include a lack of consistency in diagnostic criteria, the preparation of the patient and the performance of the test, and the c riterion standard (renal artery stenosis or renovascular hypertension) . We investigated the sensitivity and specificity of a simplified vers ion of the test, based on a single postcaptopril value of plasma renin activity, in 36 patients who were undergoing either angioplasty or su rgery for renal artery stenosis. The test demonstrated an excellent se nsitivity (96%) but a poor specificity (55%). However, the poor specif icity was related to certain clinical characteristics; high baseline p lasma renin activity measurements, female gender, current smoking, ren al dysfunction, and bilateral renal artery stenosis were all associate d with false-positive results. This simplified captopril test, when ap plied to a population with a high prevalence of renovascular hypertens ion and performed in a standardized manner, can accurately identify th ose patients unlikely to respond to intervention. However, a positive test, especially in those with the characteristics noted above, does n ot help clinical decision making because of the limited test specifici ty. (C) 1994 by the National Kidney Foundation, Inc.