July 06, 2014
One out of every 7 older adults with high blood pressure who were newly prescribed a thiazide diuretic developed a metabolic adverse event that they would not have otherwise had, according to a recent study.
The researchers compared the health at 9 months’ follow-up of 1,060 hypertensive patients 65 years or older on a daily dose of hydrochlorothiazide with the same number of patients who did not take the drug, all of whom were veterans.
Thiazide use increased risk of metabolic adverse events by 14.3% compared with 6% in nonusers, said the study, which also noted 1.8% of users developed severe adverse events compared with 0.6% of nonusers. Additionally, 3.8% of users and 2% of nonusers required ER visits or hospitalization for related treatment. The researchers said patients with 5 or more comorbidities were 3 times more likely to develop an adverse event and twice as likely to suffer hyponatremia.
Lab tests that revealed lower than normal sodium and potassium levels in patients indicated increased potential for hyponatremia and hypokalemia, according to the study. But despite these heightened risks, only 42% were monitored for the adverse events within 3 months of starting the therapy, which was a surprising and alarming rate, according to lead researcher Dr. Anil Makam, assistant professor in the department of clinical science at the University of Texas Southwestern Medical School in Dallas.
“Thiazide-type diuretics are effective antihypertensive medications that lower the incidence of strokes and heart attacks,” he said. “However, our research suggested that greater attention should be paid to the potential metabolic complications in older adults, including closer laboratory monitoring before and after the initiation of thiazides.”
Even mild hyponatremia and hypokalemia increase mortality, noted the researchers, with the former also raising the potential of fall risks, unsteady gate, and cognitive impairment. The dangers of prescribing thiazides to the elderly are clear, and may even be greater than the study indicated. According to the researchers, most patients did not have significant comorbidities such as heart failure, renal insufficiency, and dementia, when in fact elderly patients with high blood pressure are typically frail individuals with several comorbidities and altered drug metabolisms that increase overall risks of medication adverse events.
Other classes of antihypertensive medications that are just as effective as thiazides and available in low-cost generic formulations should be considered for elderly patients, noted Dr. Makam. He said blood pressure is successfully managed in non-black patients with calcium channel blockers, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers, while a calcium channel blocker is an effective alternative in black patients.
The study was published online in the Journal of the American Geriatrics Society.
1. Makam AN, Boscardin WJ, Miao Y, Steinman MA. Risk of thiazide-induced metabolic adverse events in older adults. J Am Geriatr Soc. 2014,62(6):1039-1045.