Raised aldosterone to renin ratio predicts antihypertensive efficacy of spironolactone:A prospective cohort follow-up study

Aims. Aldosterone/renin ratio is an index for inappropriate aldosterone activity, and it is increasingly being used to screen for primary aldosteronism within the hypertensive population. It may also be a good index to help predict the response to spironolactone. To assess the blood pressure response to oral spironolactone in hypertensive patients with primary aldosteronism identified with raised aldosterone to renin ratio. Methods. We conducted a prospective cohort study of hypertensive patients with raised aldosterone/renin ratio, who failed to suppress plasma aldosterone with salt loading and fludrocortisone suppression test. These patients were treated with spironolactone and were followed-up for a period of up to 3 years. Results. We studied 28 (12 male) subjects with a mean age of 55 (s.d. 10) years who were followed up for a mean period of 12.9 (7) months. At baseline, the patients were taking a mean of 2.1 (1.2) antihypertensive drugs, but despite this 16/28 (57%) had diastolic BP > 90 mmHg, 39% with systolic BP > 160 mmHg. After commencing spironolactone, three patients complained of breast tenderness but continued treatment and one patient was intolerant of spironolactone and had to stop treatment. Of the remaining 27 patients, the mean number of antihypertensive drugs used dropped to spironolactone plus 0.7 (s.d. 0.9). All but one patient (96%) achieved a diastolic BP ≤ 90 mmHg and 78% achieved a systolic BP ≤ 160 mmHg. In total 48% had BP ≤ 140/90 mmHg and 13/27 (48%) were treated with spironolactone monotherapy. Assessing only patients on drug treatment at baseline (n = 24), spironolactone significantly reduced the need for antihypertensive drugs by -0.5 (CI 0.1-1.0), P = 0.02, as well as reducing blood pressure [systolic BP -15 mmHg (CI 5-25), P = 0.007 and diastolic BP (mmHg) by -8 mmHg (CI 4-13), P = 0.001]. Conclusions. Spironolactone was a highly effective antihypertensive agent in hypertensive patients who had a raised aldosterone/renin ratio. As a raised ratio was highly predictive of nonsuppression of plasma aldosterone suggesting primary aldosteronism, it might be worthwhile using spironolactone in this subgroup of hypertensive patients with raised aldosterone/renin ratios, provided that adrenal adenomas are excluded with imaging techniques.