The Skeptical Cardiologist primarily makes decisions on blood pressure treatment these days based on patient self-monitoring. If high readings are obtained in the office, I instruct patients to use an automatic BP cuff at home and make a measurement when they first get up and again 12 hours later. After 2 weeks, they report the values to me.
I described in detail the recommended measurement technique in this 2018 post.
Although I’ve been recommending self-monitoring to my patients for decades, it is only recently that guidelines have endorsed the approach and good scientific studies verified its superiority. I was pleased when the 2017 American College of Cardiology/American Heart Association guidelines for high blood pressure gave home BP self-monitoring an IA recommendation.
And last year a very good study, the TASMNH4, was published that demonstrated the superiority of self-monitoring compared to usual care.
TASMINH4 was a parallel group randomized controlled trial done in 142 general practices in the U.K., and included patients older than 35 years with blood pressure higher than 140/90 mm Hg who were willing to self-monitor their blood pressure. Patients were randomly assigned (1:1:1) to self-monitoring blood pressure, to self-monitoring blood pressure with telemonitoring (telemonitoring group), or to usual care with clinic blood pressure measurement.
The home BP goal was 135/85 mm Hg, which was 5 mm Hg lower than the office BP goal. At 1 year, both home self-monitoring groups had significantly lower systolic blood pressure than the usual care group.
“This trial was not powered to detect cardiovascular outcomes, but the differences between the interventions and control in systolic blood pressure would be expected to result in around a 20% reduction in stroke risk and 10% reduction in coronary heart disease risk. Although not significantly different from each other at 12 months, blood pressure in the group using telemonitoring for medication titration became lower more quickly (at 6 months) than those self-monitoring alone, an effect which is likely to further reduce cardiovascular events and might improve longer term control.”
Limitations of Office Measurement
I described why I switched to home BPs in a post about the landmark SPRINT trial in 2015:
“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 … 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.”
In addition, I feel that multiple assessments of out-of-office BP over the course of the day and different days are more likely representative of the BP that we are consistently exposed to rather than a single reading in the doctor’s office.
Accuracy and technique in the doctor’s office is also an issue.
Interestingly, we have assumed that manual office BP measurement is superior to automatic, but this recent paper found the opposite: “Automated office blood pressure [AOBP] readings, only when recorded properly with the patient sitting alone in a quiet place, are more accurate than office BP readings in routine clinical practice and are similar to awake ambulatory BP readings, with mean AOBP being devoid of any white coat effect.”
A patient left a comment to that paper which is quite insightful:
“I had a high blood pressure event several years ago. Since then I have monitored my BP at home, sitting with both feet flat on the floor, not eating or drinking, not speaking or moving around, on a chair with a back, and without clothes on the arm being used for the measure. My BP remains normal.”
“I have never had my BP taken correctly in a doctor’s office. They will do it while I am speaking with the doctor, sitting on an exam table with my legs swinging, with the monitor band over my heavy winter sweater, right after I have sat down. They do not ensure that my arm is supported or at the right height. If I recommend that I take off my sweater, or move to a chair with a back, they tell me that is not needed. I have decided to refuse such measurements. How can they possibly be monitoring my health this way?”
This patient’s observations are not unique, and I suspect the majority of office BPs have most if not all of the limitations she describes.
Self-Monitoring Improves Patient Engagement
I have found self-monitoring of patient’s BP to substantially enhance patient engagement in the process. Self-monitoring patients are more empowered to understand the lifestyle factors that influence their BP and to make positive changes.
Blood pressures are amazingly dynamic and as patients gain understanding of what influences their BP they are going to be able to take control of it.
I take my BP almost daily and adjust my BP medications based on the readings. After prolonged work or exercise in heat, for example, BPs will decline to a point where I’m light headed or fatigued. Less BP medication at this time is indicated. Conversely, if I’ve been overly stressed BPs increase and upward titration of medication is warranted.
With some of my most engaged and enlightened patients, we perform similar titrations depending on their circumstances. Sometimes patients perform these titrations on their own and tell me about them at the next office visit.
What’s The Best Way To Communicate Home BP?
Many of my patients provide me with a hand-written record of their BP over 2 weeks. Some mail them to me, others bring them into the office. We scan these into the electronic medical record (EMR). I look at these and make an estimate of the average systolic blood pressure, the variation over time, and the variation during the day. It’s not feasible for me or my staff to enter the numbers or precisely obtain an average.
Some patients send us the numbers through the internet-based patient portal into the EMR. This is preferable, as I can view these and respond quickly and directly back to the patient with recommendations.
More and more patients are utilizing their smart phones to record and aggregate their health data and will bring them in for me to look at during an office visit. I’ve described one stylish and slick BP cuff, the QardioArm which has neither tubes nor wires and works through a smartphone app. Omron, also has multiple cuffs that communicate via Bluetooth to store data in a smartphone app.
Ideally, we would have a way for me to view those digitally-recorded BPs with nicely calculated averages online and within the EMR. Unfortunately, such connectivity is not routinely available.
However, for my patients who are already monitoring their heart rhythms with a Kardia mobile ECG and are connected with me online through KardiaPro Remote, I can view their BP recordings online.
I’ll discuss in detail in a subsequent post the Omron Evolv home automatic BP cuff (my current favorite), which is wireless and tubeless and connects seamlessly to KardiaPro allowing me to view both BP and heart rhythm (and weight) recordings in my patients.
To me, this empowerment of patients to record, monitor, and respond to their own physiologic parameters is the future of medicine.
Anthony Pearson, MD, is a private practice noninvasive cardiologist and medical director of echocardiography at St. Luke’s Hospital in St. Louis. He blogs on nutrition, cardiac testing, quackery, and other things worthy of skepticism at The Skeptical Cardiologist, where a version of this post first appeared.