Besides being a huge risk factor for heart disease, strokes, etc, high blood pressure can also lead to kidney disease. People with high blood pressure are at risk of developing changes that lead to scarring inside the kidneys, that could ultimately cause the kidneys to "burn out". Patients with existing chronic kidney disease (CKD), are at a higher risk of progression to end stage kidney disease when they would need either dialysis or a kidney transplant, should their blood pressure stay high/uncontrolled. In fact, after diabetes, high blood pressure is the commonest reason that people develop kidney failure. So what is the target blood pressure for someone with underlying CKD to minimize their risk of progression to end stage kidney disease?
Blood pressure control is one the high priority target that needs to be achieved in order to optimize kidney function and nurture remaining kidney function in people who have CKD. Well controlled blood pressure could make the difference between the CKD patient needing dialysis, versus containing their kidney disease at stages 1 through 4.
The idea that blood pressure needs to be controlled to a goal is now an accepted fact. But, what should this goal be is a question that is still being debated vociferously in the medical community. Blood pressure targets that apply to the average hypertensive person might not apply to the hypertensive patient who also has kidney disease. Every few years, we have seen a guideline being provided to physicians from one of the major healthcare organizations and international bodies like the Kidney Disease Improving Global Outcomes (KDIGO). And to make the average physician's job tougher, no two guidelines seem to agree with one another! Take a look at the picture below and you will realize what I am referring to:
|2014 Evidence-Based Guideline for the Management of High Blood Pressure in Adults|
Image courtesy JAMA
As you can see, the recommended target over which blood pressure should be treated and brought down seems to range anywhere from 130/80 to 150/90. These are wide variations, but lets try to understand the reasons for the disparity.
You might have noticed that earlier guidelines from around 2010-2011 and before seem to recommend a more aggressive control of blood pressure to lower targets. That, in fact, was the accepted gospel truth for most primary physicians, cardiologists, and nephrologists, till very late. However, in 2010 we had a major study on high blood pressure that was reported in the hallowed pages of the New England Journal of Medicine (NEJM). This study called the ACCORD trial showed that there was no benefit to treating high blood pressure to an aggressive low of systolic 120 mm, vs the more relaxed target of 140 mm. This flew in the face of "accepted" wisdom in the medical community which tended to believe that low blood pressure is always good, and high is bad! This trial was however not a flash in the pan, since earlier, we had seen another study called the INVEST trial that also reported no benefit of treating blood pressure too aggressively.
These developments have forced us to question our traditional thoughts about "what is a good blood pressure" (I am limiting my discussion to patients with kidney disease, since there are other special situations that are beyond the scope of this blog). And so, in cognisance of this new body of evidence, an organization (that usually has the last word on blood pressure management guidelines) called the Joint National Committee or the JNC, came out with its much-awaited set of recommendations. These are often referred in the popular media as "JNC 8". I am not going to debate the strengths and weaknesses of JNC8 (it has its fair share of controversies), but in a nutshell, it recommends that blood pressure target goal for patients with chronic kidney disease is 140/90, or below. In other words, you shouldn't need medical treatment if you tend to stay under this level on an average. If you are close to this number, you might get away with lifestyle modifications alone.
As with most recommendations, there are riders and special situations which are too extensive to debate here. But we often have something called "compelling indications" when it comes to hypertension treatment. For instance, someone with an excessive amount of protein in the urine might be put on lisinopril (a blood pressure pill), even if the blood pressure is under this goal. In this case, the blood pressure pill is being used for other indications.
To summarize, for most patients with CKD, a target goal pressure to optimize kidney function and reduce their chances of progression to end stage renal disease would be <140/90. At least that's where we stand until JNC 9!
Bradenton, Lakewood Ranch, Sarasota