Application of Captopril Challenge Test in Diagnosis, Classification and Clinical Outcomes of Primary Aldosteronism

Abstract

Background Primary hyperaldosteronism (PA) has been recommended by numerous hypertension guidelines to expand screening, early diagnosis and treatment, as a secondary hypertension disease with the highest incidence, great cardiovascular and cerebrovascular dangers but high cure rate after surgery. However, the diagnosis, classification and clinical outcomes evaluation of these patients are varied and controversial. Captopril challenge test (CCT) is expected to provide whole-course management for PA patients because it is convenient, safe and can be used directly in the community or outpatient clinic. Objective To explore the diagnostic efficacy, classification and biochemical remission assessment of CCT in patients with PA. Methods The study population consisted of 824 patients who completed the cause screening for hypertension and were enrolled in the Department of Endocrinology and Metabolism, West China Hospital, Sichuan University from October 1 th 2020 to December 30 th 2022. After screening, 247 patients with PA and 123 patients with essential hypertension (EH) were enrolled, and PA was classified into aldosterone-producing adenoma (APA, 81 patients), idiopathic hyperaldosteronism (IHA, 55 patients), and uncategorized PA (u-PA, 111 patients). The differences among the four groups were compared and the receiver operating characteristic (ROC) curve analysis showed the diagnostic performance for the prediction of PA. Secondly, the ROC curves of each post-CCT index for APA and IHA respectively were plotted. Finally, according to the postoperative clinical outcomes, the patients with unilateral adrenal resection were divided into three groups: clinical remission, clinical improvement, and no remission group. The difference between the three groups was compared, and the cut-off point of biochemical remission of CCT in APA patients was analyzed. Results The post-CCT plasma aldosterone concentration (PAC) level had the highest diagnostic efficiency for PA (AUC=0.921, 95%CI=0.893-0.950), and the cut-off was 11.7 ng/dL. The sensitivity and specificity respectively was 84.6% and 86.0%. The post-CCT aldosterone to renin ratio (ARR) also had a good diagnostic efficacy for PA (AUC=0.868, 95%CI=0.823-0.923). The cut-off was 2.8 (ng/dL) / (mU/L), and the sensitivity and specificity respectively were 82.2% and 81.0%. The post-CCT PAC>17 ng/dL can assist in the diagnosis of APA subtypes. When post-CCT PAC<11.7 ng/dL combined with post-CCT ARR< 2.8 (ng/dL) / (mU/L), APA was almost excluded. The inhibition rate of PAC after CCT and the PAC remission rate after surgery were less effective in judging the biochemical remission assessment of APA, and post-CCT PAC<11.7 ng/dL or post-CCT ARR<2.8 (ng/dL) / (mU/L) could better. Among the patients receiving surgical treatment, 87.2% had post-CCT PAC<11.7 ng/dL, and 89.7% had post-CCT ARR<2.8 (ng/dL) / (mU/L), which was close to the postoperative clinical remission level (88.0%) . Conclusion CCT can be used throughout the diagnosis, classification and clinical outcomes evaluation of PA patients. post-CCT PAC 11.7 ng/dL and post-CCT ARR 2.8 (ng/dL) / (mU/L) are good cut-off for the diagnosis, and can also be used for the classification of APA and the judgment of postoperative biochemical remission. Secondly, detection before CCT has little clinical significance and can simplify the process.

Keywords

• primary aldosteronism|captopril|captopril challenge test|aldosterone-producing adenoma|aldosterone to renin ratio|receiver operating characteristic curve