George Bakris, MD, Professor of Medicine and Director of the Hypertensive Diseases Center at the University of Chicago Medical Center, is an internationally recognized hypertension expert who specializes in complicated or refractory cases. He spoke with Renal & Urology News about various aspects of treating hypertension in patients with chronic kidney disease.
Should clinicians tolerate high blood pressure more in the elderly than in younger people?
Dr. Bakris: Certainly, aging increases blood pressure, but not to the point where you have to tolerate it at very high levels. In dialysis patients, I can’t answer the question in terms of any specific number, but the epidemiology would indicate that if the blood pressures are between 130 and 145 mm Hg, your outcomes are probably going to be far better than if they are above that or below that.
In 70-year-olds with CKD stages 3 and 4, you should not be shooting for a blood pressure that is 120 mm Hg. At the same time, you should not be allowing them to have blood pressures of 160 mm Hg.
The current recommendations for hypertension in the elderly, that is, anybody over age 65, is that the [systolic] blood pressure be lowered to less than 140 mm Hg and if the patient can’t tolerate it or if it’s too difficult, then the blood pressure should be less than 150 mm Hg. So a [systolic] blood pressure in the range of between 135 and 145 mm Hg is perfectly acceptable in people with advanced CKD who do not have proteinuria. If they do have proteinuria, you should try to get the blood pressure below 130 mm Hg if the patients can tolerate it.
Is low blood pressure in dialysis patients associated with increased mortality?
Dr. Bakris: Yes, but first we have to qualify what low BP is. The risk starts to go up when you get down to numbers below 115 mm Hg. Clearly, people who have numbers between 100 and 110 consistently when they come for dialysis tend not to do as well [as patients with higher BP]. One of the major reasons is thought to be heart failure or low perfusion states.
Heart failure is one of the most common causes of death in dialysis patients. Low blood pressure in those patients is not indicative of what it would be, say, in somebody who is 25 years old with normal kidneys.
It’s indicative of a failing heart in most circumstances or severe coronary disease associated with a failing heart. As a result, those people do have a higher mortality rate. It is important to recognize that these patients make up a very difficult group.
Most of the therapies that are given to people with heart failure would further lower their blood pressure and potentially make them unavailable for dialysis because the pressures would be too low. There has been no trial that has actually randomized dialysis patients with documented heart failure to different forms of treatment.
Is it wise to lower BP in dialysis patients via ultrafiltration rather than medication?
Dr. Bakris: There has been a large temptation to do this and there’s certainly very good data to suggest that the major reason for dialysis patients not having good blood pressure control is the failure to appropriately ultra filter. The data are pretty good on that.
Every [research] group that looked at this, both in the United States and Europe, has found evidence supporting the use of ultrafiltration as a way to achieve blood pressure control since you obviously can’t give diuretics and all other [antihypertensive] medications do not work as well as they should [in these patients]. And most of these patients are non-adherent with their volume intake between dialysis sessions and unless you ultra filter them appropriately, you’ll not be able to get them under control.
So I think as a therapeutic modality in dialysis patients, as more and more data are emerging, I would say that it will be a treatment of choice for refractory hypertension [in dialysis patients] in a couple years. Interestingly, as a corollary to this, the most common cause of resistant hypertension in people with normal kidneys is the failure to use adequate diuretics or even use them at all. In this situation, where diuretics would not be useful, ultrafiltration would be a substitute for appropriate volume management.
What important clinical questions related to hypertension need to be addressed?
Dr. Bakris: Better education in how to use appropriate medications. Proper dosing of antihypertensive medications is not taught even in nephrology programs. It’s kind of [learning] by osmosis. That’s unfortunate because there are a lot of subtleties that are then missed.
We have now over 130 different antihypertensive medications in eight different classes. If someone truly understands and knows how to mix and match these blood pressure medications, they should be able to control most peoples’ blood pressure. Unfortunately, this is not the case, and this is why there are board-certified hypertension specialists. They know how to mix and match antihypertensive medications.
With CKD patients, appropriately dosed diuretics absolutely have to be part of your armamentarium. Dosing for the level of kidney function is important. Patients with GFR’s [glomerular filtration rates] of 40 [mL/min/1.72 m2] are using hydrochlorothiazide in low doses is totally ineffective.
New guidelines are going to be emphasizing evidence-based data supporting the use of chlorthalidone and indapamide. There’s a relative underuse of torsemide for treating BP, a long-acting loop diuretic. It is generic, cost is not an issue, and it’s phenomenal for treating [high] blood pressure.
We now have new approaches, including renal sympathetic nerve denervation and carotid baroreceptor stimulation, that are still experimental but certainly would offer a lot of potential blood pressure lowering benefit to people with refractory or resistant hypertension even with GFR’s down to 45.
In addition, clinicians need to understand that hypertension and high blood pressure are not the same thing. Hypertension is a genetic disease, with elevations in blood pressure occurring at an early age and which may or may not be hormonally or renally mediated. On the other hand, elevations in blood pressure that fluctuate are a manifestation of a whole panoply of different events that occur over a day in your life and does not necessarily equal hypertension.