Home Versus Office Blood Pressure and the “Landmark” NIH Blood Pressure Trial

The NIH yesterday announced that they had prematurely ended a large trial looking at outcomes when hypertensive patients (aged >50 years) were treated to lower versus higher blood pressure goals.

The data showing a benefit in those treated to the lower goal were apparently so compelling the scientists tasked with monitoring them felt they needed to be published as soon as possible.

According to the NIH press release

“the intervention in this trial, which carefully adjusts the amount or type of blood pressure medication to achieve a target systolic pressure of 120 millimeters of mercury (mm Hg), reduced rates of cardiovascular events, such as heart attack and heart failure, as well as stroke, by almost a third and the risk of death by almost a quarter, as compared to the target systolic pressure of 140 mm Hg”

These data won’t be published for several months but if they hold up under close scientific scrutiny it will change the way I and other physicians treat hypertension dramatically.

The lower BP goal patients in this study were on three BP meds versus two for the higher goal. To achieve a goal of 120 mm Hg I think it is highly likely that I will have to add an additional BP med to all of my patients.

With more stringent BP goals it will become crucial to make sure that we are getting accurate BP data on our patients. But what kind of BP data should we be looking at and what technique for obtaining the BP should be employed?

Home Versus Office Blood Pressure

Every patient I see in my office gets a BP check. This is typically done by one of the office assistants who is “rooming” the patient using the classic method with , listening with stethoscope for Korotkov sounds. If the BP seems unexpectedly high or low I will recheck it myself.

Often the BP we record is significantly higher than what the patient has been getting at home or at other physician offices.

There are multiple factors that could be raising the office BP: mental stress from driving to the doctor or being hurried or physical stress from walking from the parking lot.

Conscious or subconscious anxiety about what the doctor may find is thought to  play a role, so-called “white coat” effects.

Consequently I rely more on home BP monitoring when making decisions on treatment initiation or change

bpcuff
The skeptical cardiologist’s home BP cuff. Note the early AM systolic BP which is acceptable under current BP guidelines but would be unacceptable if goal becomes <120 mm Hg. Also note that music is about to be played which will lower BP. There are 3 directions in the graphic. 1. Position cuff 0.8-1.2″ above elbow 2. Center tuber over middle of arm 3. Allow room for two fingers to fit between the cuff and your arm.

Accurate automatic BP devices can be purchased from Walgreen’s or CVS for around $40.

I recommend devices that have a cuff that goes around the upper arm and have as few frills as possible.

I usually ask patients to take a BP in the morning and evening daily for two weeks and report the values to me.

The SPRINT study likely, however, used in office BP measurements and followed the BP taking recommendations on their website as follows:

  • Don’t drink coffee or smoke cigarettes for 30 minutes prior to the test.
  • Go to the bathroom before the test.
  • Sit for 5 minutes before the test.

The Harvard Health website adds even more requirements for taking BP

  • Avoid caffeinated or alcoholic beverages, and don’t smoke, during the 30 minutes before the test.
  • Sit quietly for five minutes with your back supported and feet on the floor.
  • When making the measurement, support your arm so your elbow is at the level of your heart.
  • Push your sleeves out of the way and wrap the cuff over bare skin.
  • Measure your blood pressure according to the machine’s instructions. Leave the deflated cuff in place, wait a minute, then take a second reading. If the readings are close, average them. If not, repeat again and average the three readings.
  • Don’t be too concerned if a reading is high. Relax for a few minutes and try again.

What is the True Blood Pressure?

It seems to me that the most important thing in blood pressure control is what the blood pressure is the majority of the time. Consequently I have always questioned the advice to throw out high readings and to only utilize BP measurements obtained after sitting quietly for 5 minutes.

After all, if you are active most of the day as you should be, it would be rare for you to be sitting quietly doing nothing for 5 minutes. The BP  you first take, although higher than one 5 minutes later, might be a more accurate reflection of your average BP during the day.

Most days you are exposed to a variety of stressors related to work or personal and family situations and your BP is likely reacting to these stressors. The “sitting quietly for 5 minutes” BP is not reflective of these higher readings.

In addition, if you only take your BP when your bladder has just been emptied and you have not had any caffeine it is likely an underestimate of the average daily BP which includes full bladders and cups of coffee.

For these reasons I only tell my patients to take the BP twice a day. I don’t instruct them to sit quietly or throw out the high readings or avoid caffeine. I want BPSs that truly represent the normal daily fluctuations. I don’t want to cherry pick “good” BPs.

I am eagerly awaiting the publication of the SPRINT data which may alter BP treatment dramatically.

Until then I’m sticking to the guidelines published two years ago (and which I wrote about here) which aimed for SBP <140 mm Hg for patients less than 60 years and <150 mm Hg for those older than 60.

diastolically yours

-ACP

 

 

6 thoughts on “Home Versus Office Blood Pressure and the “Landmark” NIH Blood Pressure Trial”

  1. Very interesting………..you forget the male teaction in the attractive female assistant. Another good reason to use the home metrics…..always quiet in that environment……don’t you agree?

    1. Hm. Home metrics.
      I find, martyr to “white coat” that I am, that I have a reaction to… myself – velcroing on the cuff and relaxing for a timed five minutes and all.
      Performance anxiety.
      Which is why I’m thinking that the usefulness of 24 hour ambulatory monitoring ought to be discussed at this point.
      Useful? Cost effective?

      1. I find ambulatory blood pressure monitoring to be useful. Interestingly, it is hard to find hospitals which offer this due to low reimbursement.
        I think your case would be a wonderful use for ambulatory monitoring.
        For patients who have high Bps in my office but good at home (who I deem trustworthy) I don’t routinely order the ambulatory monitoring.

  2. I agree on taking your blood pressure at anytime even if you have been active. I know I am not sitting quietly for most of the time.

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