Potential effects of age on screening for primary aldosteronism

Aldosterone/renin ratio (ARR) is currently regarded as the most reliable and available screening test for primary aldosteronism (PA), however, the falling accuracy of ARR with increasing age has posed crucial challenge for PA screening among older-aged population. To clarify potential effects of age on screening for PA, 216 subjects with PA and 657 subjects with non-PA were recruited and subdivided into four age groups (⩽39, 40-49, 50-59 and ⩾60 years) and their biochemical parameters were compared. As expected, plasma renin activity (PRA) lowered more than plasma aldosterone concentration (PAC) and led to gradually elevated ARR with increasing age in the non-PA group (P<0.001), whereas this phenomenon was unconspicuous in the PA group. The best cut-off values of ARR for PA screening were elevated in subjects ⩾50 years, whereas the area under the receiver operating characteristic curves (AUCs), sensitivity, specificity and Youden's index (YI) of ARR were declined with increasing age, especially in patients ⩾60 years (AUC=0.863, sensitivity=95.2%, specificity=69.0%, YI=0.643). The AUCs of PAC increased with increasing age and even slightly surpassed that of ARR in patients ⩾60 years (AUCPAC=0.884). Our data suggest that the criteria of ARR for PA screening in patients ⩾50 years may need setting higher; the falling accuracy of ARR with increasing age, especially in patients ⩾60 years, could be improved by taking into account the absolute value of the PAC when applicable by the center.