Key result
The 25 mg oral captopril test showed limited capacity to discriminate primary aldosteronism from primary hypertension, with an AUC of 0.664 at 120 minutes compared to 0.595 for basal ARR.
Why the study?
Does the 25 mg oral captopril test improve the diagnostic accuracy for primary aldosteronism in hypertensive patients with an increased ARR compared to basal ARR?
Observational (n=62)
Does the 25 mg oral captopril test improve the diagnostic accuracy for primary aldosteronism in hypertensive patients with an increased ARR compared to basal ARR?
Absolute Event Rate: 0.664% vs 0.595%
The 25 mg oral captopril test provides only marginal diagnostic improvement over basal ARR and is not recommended for confirming primary aldosteronism due to poor discrimination from primary hypertension.
Captopril testing adds minimal diagnostic value over basal ARR; leaves open the need for superior confirmatory strategies in suspected primary aldosteronism.
INTRODUCTION: The aldosterone/renin ratio (ARR) is the first line screening test for primary aldosteronism (PA). However, in hypertensive patients with an increased ARR, PA needs to be confirmed by other means. METHODS: A 25 mg oral captopril test was performed in 16 healthy subjects to obtain reference values for aldosterone and ARR at 120 minutes after the test. Subsequently these data were applied to 46 hypertensive patients screened for PA with an increased ARR. RESULTS: At 120 minutes after the captopril test ARR decreased in healthy subjects within a narrow range, but remained high in patients with PA and in patients with primary hypertension, especially for those with low renin characteristics. At 120 minutes after captopril, the range of ARR in primary hypertensive patients overlapped in 88% of the cases with the range of the ARR in the PA patients. Sensitivity and specificity of basal ARR and ARR after the captopril test to diagnose PA, calculated as receiver operator characteristics, showed an area under the curve of 0.595 for basal ARR and 0.664 for ARR at 120 minutes after the test. CONCLUSION: The ARR at 120 minutes after the captopril test is only marginally better than basal ARR in diagnosing PA in hypertensive patients screened with an increased ARR. Owing to an overall limited capacity to clearly discriminate PA from primary hypertension, the test could not therefore be recommended for the confirmatory diagnosis of PA.
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Westerdahl et al. (2011) conducted an observational in Primary aldosteronism and primary hypertension (n=62). Captopril test vs. Basal aldosterone/renin ratio was evaluated on Area under the curve (AUC) for diagnosing primary aldosteronism. The 25 mg oral captopril test showed limited capacity to discriminate primary aldosteronism from primary hypertension, with an AUC of 0.664 at 120 minutes compared to 0.595 for basal ARR.
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