High rates of undiagnosed primary aldosteronism suggest role for GP screening

Thursday, 3 Mar 2022

One in seven patients newly diagnosed with hypertension in primary care have primary aldosteronism (PA), an Australian study has found.

The high rate suggests that it would be useful to screen patients for PA before starting antihypertensive treatment, thus avoiding years of diagnostic delay that may lead to patients developing end-organ damage, according to researchers at Monash Health, Melbourne.

In their paper published in the MJA they say that people with the condition have poorer cardiovascular disease outcomes than people with essential hypertension matched for blood pressure, and few receive targeted treatment because the condition is perceived to be rare and is seldom recognised.

They note that the Endocrine Hypertension Service at Monash Health found the median time between diagnosis with hypertension and referral to the PA specialist service was almost 14 years, and that 42% patients with confirmed PA had end-organ damage at the time of referral.

But if diagnosed early, treatments such as spironolactone could optimise BP control and mitigate many of the adverse cardiovascular consequences of excessive aldosterone secretion, they wrote.

They therefore arranged GP screening for 247 adults with newly diagnosed hypertension who had not started taking antihypertensive medications.

Patients were screened for PA using the aldosterone-to-renin ratio (ARR) and referred for saline suppression testing at the Endocrine Hypertension Service if they had two ARR values exceeding 70 pmol/mU.

One quarter of patients (62/247) had elevated ARR values on screening, and subsequently 35 (14%) had PA confirmed by saline suppression testing.

There were no baseline characteristics associated with a diagnosis of PA.

The study investigators said the detection rate of 14% was much higher than current diagnosis rates of 0.1%, and suggested a potential role for screening in primary care to enable early detection of PA.

“Our study suggests that PA is much more frequent in unselected general practice patients with hypertension than is recognised. Our finding also highlights the central role of GPs in the early detection of this treatable form of hypertension,” they wrote.

They noted that currently only a handful of patients with hypertension have aldosterone levels measured and the new findings suggested that “a considerable number of people with undiagnosed PA could be missing targeted treatment”.

“We found that a large majority of people diagnosed with PA benefited from targeted treatment; hypertension was resolved for two by adrenalectomy, and blood pressure control and normalisation of renin level was achieved by 18 of 25 patients prescribed mineralocorticoid receptor antagonist monotherapy,” they said.

“Our findings suggest that it would be useful to evaluate the cost-effectiveness of screening all patients with hypertension for PA in primary care before initiating antihypertensive treatment.

“If cost-effective and acceptable to patients, PA screening could substantially change the management of hypertension in Australian primary care, and also bring GPs to the forefront of the timely detection and optimal management of a common disease,” they concluded.

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