CHICAGO– Older black Americans are more likely to have hypertension and less likely to have it under control than are their white counterparts, yet paradoxically they are also on more antihypertensive medications, according to a new analysis from the landmark ARIC study.
This finding is at odds with the conventional wisdom, which holds that the higher rate of poorly controlled hypertension in black patients is due to racial disparities in treatment, with blacks receiving less adequate treatment.
Dr. Michael D. Miedema
“In our study it appeared they were very well treated, yet they still didn’t achieve the same blood pressure as the older white patients,” Dr. Michael D. Miedema said in presenting the ARIC (Atherosclerosis Risk in Communities) findings at the American Heart Association Scientific Sessions.
Indeed, 88% of elderly black hypertensive patients were on at least one antihypertensive medication, compared with 71% of white hypertensives patients. Black hypertensive patients were also more likely to be on three or more antihypertensive drugs, by a margin of 27% to 16%.
“So it’s not for lack of antihypertensive medication use,” according to Dr. Miedema, a cardiologist at the Minneapolis Heart Institute.
The ARIC study is an ongoing longitudinal study of cardiovascular disease in older black and white men and women. The National Heart, Lung, and Blood Institute–funded study began in the late 1980s. Dr. Miedema’s analysis included 6,088 participants in the fifth clinical visit, which took place in 2011-2013. The subjects’ mean age was 75.6 years, and 23% were black. A total of 82% of subjects had hypertension as defined by blood pressures greater than 140/90 mm Hg; 81% of those with hypertension were aware of that fact. Put another way, nearly 20% of elderly hypertensive subjects were unaware they had hypertension, he noted.
One-third of ARIC participants had diabetes, 30% had cardiovascular disease, and 37% had chronic kidney disease. The prevalence of hypertension in subjects with diabetes or chronic kidney disease was 92%; in those without either comorbidity, it was 69%.
Of the total study population, 63% were at the blood pressure goals defined by JNC-7. This figure shot up to 79% using the less aggressive blood pressure goals recommended in the 2014 expert panel report (JAMA 2014;311:502-20), namely, targets of less than 150/90 mm Hg in individuals aged 60 years or older, and 140/90 in those with diabetes or chronic kidney disease. Thus, one in six elderly subjects in ARIC were reclassified from having high blood pressure to normal blood pressure through the use of the 2014 guidelines.
“Despite the more lenient 2014 blood pressure goals and a high rate of antihypertensive medication use, almost 20% of our total sample were not at goal blood pressure as defined by the 2014 expert committee. This high rate of uncontrolled blood pressure may be caused by a lack of awareness, treatment inertia, or medication nonadherence; it’s hard to say. But further efforts aimed at improving detection and control of hypertension in older individuals remain warranted,” Dr. Miedema commented.
Regardless of whether the 2003 JNC-7 guidelines or the 2014 expert panel recommendations were applied as the yardstick, elderly black patients with hypertension were an absolute 10%-15% less likely to be at target blood pressure, compared with their white counterparts.
It’s possible that the worse blood pressure control in black patients was brought about in part to less-appropriate drug prescribing. The most commonly used class of antihypertensive medications in both black and white hypertensives was ACE inhibitors/angiotensin receptor blockers (ARBs), even though both JNC-7 and the 2014 expert panel guidelines recommend diuretics or calcium channel blockers as first-line antihypertensive therapy in black patients. That’s because black patients with hypertension are often in a low renin state, in which ACE inhibitors and ARBs are less effective. Confusing the picture, however, is the fact that diabetes and chronic kidney disease were particularly prevalent among older black hypertensive patients, and ACE inhibitors and ARBs are preferentially guideline-recommended in patients with those diseases.
Dr. Miedema reported having no financial conflicts of interest.