Docs Drop Ball on Primary Aldosteronism Testing

Testing practices for primary aldosteronism, a common cause of secondary hypertension, remained inadequate over nearly 2 decades, according to a large study of Veterans Health Administration data.

Among 269,010 U.S. veterans with treatment-resistant hypertension, only 1.6% were tested for primary aldosteronism in the median 3.3 years of follow-up after meeting testing criteria, a group led by Jordana Cohen, MD, MSCE, of the University of Pennsylvania in Philadelphia, reported in the Annals of Internal Medicine.

“Testing rates ranged from 0% to 6% across medical centers and did not correlate to population size of patients with apparent treatment-resistant hypertension. Testing rates also did not change meaningfully over nearly 2 decades of follow-up despite an increasing number of guidelines recommending testing for primary aldosteronism in this population,” Cohen and colleagues wrote.

The findings reconfirm below 3% testing rates previously reported at smaller health systems in California, Illinois, and New York. Prevalence of primary aldosteronism is an estimated 11% in people with normal blood pressure (BP) and 20% in those with treatment-resistant hypertension.

Screening for this modifiable cardiovascular disease risk factor, based on a simple plasma aldosterone-renin test, can help identify candidates for guideline-recommended mineralocorticoid receptor antagonist (MRA) therapy and adrenalectomy.

In the study, people who were tested for primary aldosteronism were more likely to start MRA therapy (HR 4.10, 95% CI 3.68-4.55), especially among those with a history of hypokalemia.

“The consequences of undertesting for primary aldosteronism and underuse of MRAs in patients with apparent treatment-resistant hypertension may be substantial, potentially increasing morbidity and mortality,” according to Cohen’s group.

Veterans were more likely to be tested if they had consultation with nephrologists (HR 2.05, 95% CI 1.66-2.52) or endocrinologists (HR 2.48, 95% CI 1.69-3.63) — subspecialists who care for patients already diagnosed with primary aldosteronism.

Cardiologists appeared to be no better than primary care at screening appropriate patients with resistant hypertension.

“Thus, we suspect that many of the providers who are not testing for PA [primary aldosteronism] may not be doing so because they are less familiar with the benefits of screening for PA in these patients, how to perform screening, how to interpret the results, and whether patients should be referred for further evaluation by a subspecialist,” Cohen told MedPage Today.

She suggested that provider education and tools such as electronic health record clinical decision support applications may help improve screening rates.

The retrospective cohort study included 269,010 patients with resistant hypertension (median age 65 years, 4% women).

All had received primary care in the VA from 2000 to 2017. The group comprised 81% who had two high BP readings (at least 1 month apart) on three antihypertensive drugs and 19% whose BP control required four or more antihypertensive classes.

Limitations of the study included a predominantly male cohort and the potential for BP misclassification. There was also a lack of confirmatory testing for primary aldosteronism.