Blood Pressure -- Take It Home and Sleep on It
Blood Pressure -- Take It Home and Sleep on It
Hi, I'm Dr. Henry Black. I'm Clinical Professor of Internal Medicine at the New York University School of Medicine, Immediate Past President of the American Society of Hypertension, and an observer of what the Eighth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 8) is going to say and what it's going to talk about. I was involved in JNC 6 and JNC 7, but not in JNC 8. Among the things I think they're going to have to address is how we use out-of-office blood pressure. I think we've learned that masked hypertension (ie, individuals who are normal in the office or seemingly normal in the office, but have high blood pressure at home or out of the office) is the opposite, in many ways, of white coat hypertension.
Now as we blend into more and more home monitoring and especially ambulatory blood pressure monitoring, it's quite clear that there are probably, in absolute numbers, more people with masked hypertension than white coat hypertension. But there's one thing that masked hypertension, when we measure it at home with our own cuff, never picks up, and that's our blood pressure when we're sleeping; only ambulatory blood pressure monitoring can tell you that. No one is about to wake up every hour or so and check his or her blood pressure, and then I'm not sure it would be an accurate measurement anyway.
So Jan Staessen's group looked at the importance of nighttime blood pressure (BP) compared with daytime BP, compared with the 24-hour BP, compared with the difference (ie, night-to-day BP ratio), and whether you were called a dipper or a non-dipper to see the prognostic importance of that nighttime blood pressure. A non-dipper is someone whose blood pressure falls less than 10%, generally, when you look at daytime vs nighttime. A dipper is someone whose [blood pressure] falls 10% or more, sometimes 15% or more. And then we have excessive dippers -- people who fall more than that, often as much as 30%, whose risk seems the highest.
While they looked at observational studies and clinical trials, they found 16 clinical trials that met their criteria for prospective and valid studies, and they had about 9000 individuals in observational studies. The findings are extremely consistent: for every 10% increase in nighttime blood pressure relative to the comparison, there was about a 15% increase in risk for all-cause mortality, as well as cardiovascular events. This was exactly the same number as seen in the clinical trials. The addition of daytime blood pressure to that value didn't change things very much, and when you added whether someone was a dipper or not, or the ratio between day and night, that didn't change things very much either. So what this is beginning to tell us is that, as we begin to focus our efforts on who we should treat and how we should treat, knowing the nighttime blood pressure is extremely important.
Now unfortunately, how do you operationalize this so that people will begin to treat the nighttime blood pressure, assuming it's high? Well, you could use very long-acting drugs; that's maybe one of the reasons a drug like chlorthalidone has been particularly helpful, although there are other explanations for that. Or you could give blood pressure pills at night instead of in the morning. This has been suggested, but I have concerns about that because most of the drugs (the pharmacokinetics and pharmacodynamics of the antihypertensives we use) have been based on taking the pills in the morning.
I think this is an important area for further investigation. Should we see how well all of our antihypertensives work on nighttime blood pressure? Should we be concerned about people getting up in the middle of the night, for the usual reasons, and having their blood pressure be too low because the drug is short-acting? How much does sleep apnea matter in this? Is this why the blood pressures at night don't go down as much as they might or their blood pressures are higher? Are there neurohumoral effects that happen at night that we don't see during the day?
So I think we need to begin to use this technique much, much more, so we can do better. We can really see who's at risk, and not just simply use a couple of office readings or even a couple of home readings, to decide what to do. I look forward to further research in this. I think this is going to be quite interesting and quite important. Thank you very much.
Hi, I'm Dr. Henry Black. I'm Clinical Professor of Internal Medicine at the New York University School of Medicine, Immediate Past President of the American Society of Hypertension, and an observer of what the Eighth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 8) is going to say and what it's going to talk about. I was involved in JNC 6 and JNC 7, but not in JNC 8. Among the things I think they're going to have to address is how we use out-of-office blood pressure. I think we've learned that masked hypertension (ie, individuals who are normal in the office or seemingly normal in the office, but have high blood pressure at home or out of the office) is the opposite, in many ways, of white coat hypertension.
Now as we blend into more and more home monitoring and especially ambulatory blood pressure monitoring, it's quite clear that there are probably, in absolute numbers, more people with masked hypertension than white coat hypertension. But there's one thing that masked hypertension, when we measure it at home with our own cuff, never picks up, and that's our blood pressure when we're sleeping; only ambulatory blood pressure monitoring can tell you that. No one is about to wake up every hour or so and check his or her blood pressure, and then I'm not sure it would be an accurate measurement anyway.
So Jan Staessen's group looked at the importance of nighttime blood pressure (BP) compared with daytime BP, compared with the 24-hour BP, compared with the difference (ie, night-to-day BP ratio), and whether you were called a dipper or a non-dipper to see the prognostic importance of that nighttime blood pressure. A non-dipper is someone whose blood pressure falls less than 10%, generally, when you look at daytime vs nighttime. A dipper is someone whose [blood pressure] falls 10% or more, sometimes 15% or more. And then we have excessive dippers -- people who fall more than that, often as much as 30%, whose risk seems the highest.
While they looked at observational studies and clinical trials, they found 16 clinical trials that met their criteria for prospective and valid studies, and they had about 9000 individuals in observational studies. The findings are extremely consistent: for every 10% increase in nighttime blood pressure relative to the comparison, there was about a 15% increase in risk for all-cause mortality, as well as cardiovascular events. This was exactly the same number as seen in the clinical trials. The addition of daytime blood pressure to that value didn't change things very much, and when you added whether someone was a dipper or not, or the ratio between day and night, that didn't change things very much either. So what this is beginning to tell us is that, as we begin to focus our efforts on who we should treat and how we should treat, knowing the nighttime blood pressure is extremely important.
Now unfortunately, how do you operationalize this so that people will begin to treat the nighttime blood pressure, assuming it's high? Well, you could use very long-acting drugs; that's maybe one of the reasons a drug like chlorthalidone has been particularly helpful, although there are other explanations for that. Or you could give blood pressure pills at night instead of in the morning. This has been suggested, but I have concerns about that because most of the drugs (the pharmacokinetics and pharmacodynamics of the antihypertensives we use) have been based on taking the pills in the morning.
I think this is an important area for further investigation. Should we see how well all of our antihypertensives work on nighttime blood pressure? Should we be concerned about people getting up in the middle of the night, for the usual reasons, and having their blood pressure be too low because the drug is short-acting? How much does sleep apnea matter in this? Is this why the blood pressures at night don't go down as much as they might or their blood pressures are higher? Are there neurohumoral effects that happen at night that we don't see during the day?
So I think we need to begin to use this technique much, much more, so we can do better. We can really see who's at risk, and not just simply use a couple of office readings or even a couple of home readings, to decide what to do. I look forward to further research in this. I think this is going to be quite interesting and quite important. Thank you very much.
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