Diagnostic Accuracy of the Aldosterone–to–Active Renin Ratio for Detecting Primary Aldosteronism

CONTEXT: The aldosterone–to–active renin ratio (AARR) is the recommended screening test for primary aldosteronism (PA), but prospective study data on its sensitivity and specificity are sparse. OBJECTIVE: To investigate the diagnostic accuracy of the AARR for detecting PA. DESIGN: Prospective diagnostic accuracy study. SETTING: This study was conducted from February 2009 to August 2015 at the outpatient clinic of the Department of Endocrinology and Diabetology of the Medical University of Graz, Austria. PARTICIPANTS: Four hundred patients with arterial hypertension who were referred to a tertiary care center for screening for endocrine hypertension. INTERVENTION: Participants had a determination of the AARR (index test) and a second AARR determination followed by a saline infusion test (SIT) after 2 to 6 weeks. PA was diagnosed in individuals with any AARR ≥3.7 ng/dL/µU/mL [including a plasma aldosterone concentration (PAC) of ≥9 ng/dL] who had a PAC ≥10 ng/dL after the SIT. We did not substantially alter antihypertensive drug intake. MAIN OUTCOME MEASURES: Primary outcome was the receiver-operating characteristic (ROC) curve of the AARR in diagnosing PA. RESULTS: A total of 382 participants were eligible for analyses; PA was diagnosed in 18 (4.7%) patients. The area under the ROC curve of the AARR in detecting PA was 0.973 (95% CI, 0.956 to 0.990). Sensitivity and specificity for a positive AARR in diagnosing PA were 100% (95% CI, 81.5% to 100.0%) and 89.6% (95% CI, 86.0% to 92.5%), respectively. CONCLUSIONS: The AARR has good diagnostic accuracy for detecting PA.