SAN FRANCISCO – The best way to make sure that patients are taking their blood pressure medications is to screen their urine for the drugs and metabolites, according to Robert Carey, MD, professor of medicine and dean emeritus of the University of Virginia, Charlottesville.
Dr. Carey shared his thoughts on the matter during his presentation on treatment resistant hypertension, at the joint scientific sessions of the AHA Council on Hypertension, AHA Council on Kidney in Cardiovascular Disease, and American Society of Hypertension.
Dr. Robert Carey
In up to about half the cases of apparent resistant hypertension, people simply aren’t taking their medications. Urine screening, “I believe, is the most accurate and best method of verifying adherence,” far more reliable than asking patients, or counting prescription refills, he said.
“I’m sort of a mad dog on documenting adherence because I think if we don’t document it and treat it, we will be stuck with a lot of inertia, and things won’t get better,” Dr. Carey said. He recommended speaking with patients, getting their permission to check urine levels, and reporting back results. It won’t make a difference in every case, but sometimes it will, especially if there’s an intervention to improve adherence, he noted.
Urine screening is available in most teaching hospitals and in commercial labs. “I think we will be seeing more and more availability. It has been demonstrated to be cost effective,” he said.
If adherence isn’t a problem, obesity, high sodium intake, and other lifestyle issues should be addressed, as well as the use of drugs that can raise blood pressure, especially NSAIDS, contraceptives, and hormone replacement therapies.
A workup for secondary causes also is in order. About 20% of patients will have primary aldosteronism, so all patients should be screened. Renal parenchymal disease and renal vascular disease also are common. Renal artery stenosis usually can be managed medically and rarely requires stenting. “One might take the tack of nonscreening until there’s a reduction in renal function or blood pressure goes way out of control,” Dr. Carey said.
Pheochromocytoma and Cushing’s syndrome are rare causes. Obstructive sleep apnea also is on the list “but I’m not sure it should be there. For one thing, CPAP [continuous positive airway pressure] only lowers blood pressure 1 or 2 mm. Secondly, CPAP does not prevent cardiovascular disease events in patients with moderate to severe sleep apnea and established cardiovascular risk,” he said.
If there’s no secondary cause that can be addressed, “the first thing to do is check the diuretic, and substitute in a long-acting, thiazide-like diuretic, either chlorthalidone or indapamide.” They lower blood pressure more effectively than do the thiazide diuretics, such as chlorothiazide and hydrochlorothiazide. They also provide better protection against cardiovascular events. “Once you make that substitution, you need to add a mineralocorticoid receptor antagonist, spironolactone or eplerenone. We have excellent data for both [classes of] diuretics to be added,” Dr. Carey said.
“Once we get beyond that point, we have to search the literature, and generally, we’ll come up with a goose egg in terms of randomized clinical trials. Another step is to add a beta-blocker or a vasodilating beta-blocker, [but] you would need to know precisely the mechanism of vasodilation,” he noted. After that, “you could add hydralazine or minoxidil,” a more potent vasodilator, but they have to be given with a beta-blocker and diuretic. If those approaches fail, “consider referring to a hypertension specialist,” he said.
Dr. Carey did not report any industry ties.