Search This Blog

Follow by Email

Tuesday, July 12, 2011

High blood pressure: who actually has it?

Hypertension is defined as the abnormal elevation of the pressure of blood within the arteries as measured most often by a blood pressure cuff.  About 1 in 3 Americans has hypertension (which is the same thing as high blood pressure and has almost nothing to do with stress or anxiety.) When I finished medical school about 25 years ago, hypertension was diagnosed in an adult when the blood pressure was above 140/90 mm of mercury. In the last several years, since mortality pretty much just increases with increasing blood pressure, lower levels of blood pressure have been identified as being abnormal. Now a person has prehypertension if their systolic (top number) blood pressure is between 120 and 139 or if their diastolic (bottom number) blood pressure is between 80 and 89.

High blood pressure is a big deal because it increases a person's risk for stroke, heart attack and kidney failure. It is also mostly completely silent, causing no discomfort except at very high levels. The only way to identify hypertension is through having the blood pressure checked, usually at a doctor's office.

In the June 21 issue of the Annals of Internal Medicine, Dr. Benjamin Powers and colleagues from the VA medical center in Durham, North Carolina, compared blood pressure measurements in clinics, by researchers and by patients in their homes to see how we actually diagnose and treat that most common of diseases. What they found has major implications for most patients who have been told they have high blood pressure, and for all of us who are interested in providing rational and appropriate care.

All studies that look at the treatment of blood pressures are supposed to use a standard method of measuring it.  The patient should be sitting down, not speaking, with back supported, feet flat on the floor, after 5 minutes of rest.  If a person has a blood pressure over 139/89 when measured in this way, on more than one occasion, that person can be diagnosed with hypertension. Unfortunately blood pressure is seldom measured this way in actual practice. I think that most people who have ever had a blood pressure measurement done have experienced at least one if not many deviations from this protocol. We often measure blood pressure on the fly, right after a patient has sat down, while interviewing them, sometimes when they are sitting on the exam table with their feet dangling and back un-supported. We reassure ourselves that it doesn't really matter, but it actually does.  The article shows that blood pressures taken by patients, by doctors' offices and by research personnel (who do it properly) do not agree. On average, clinic blood pressures are higher than home measurements and those are higher than research measurements.  Measuring the blood pressure several times at the office can significantly help improve the accuracy of the diagnosis, and using 5 or 6 separate measurements provides the best results.

Another statistic that is interesting from this study is that, using doctor's office blood pressure measurements, only 28% of patients are found to have good blood pressure control. If we use the patient's own blood pressure measurements from their home machines, 47% have good blood pressure control, and if research personnel do the measurements, using proper technique, 68% of patients are in good control. To me this sounds like, because of shoddy blood pressure measurements 40% of our patients are mistakenly told that their blood pressure is too high, which would lead to expensive medication prescriptions and followup appointments.

Reviewing various sources on the subject, it appears that the condition hypertension costs the US nearly 80 billion dollars yearly of which maybe 25-30 billion dollars goes to actually treating hypertension (medications and office calls). The rest of this cost is presumably related to treating the conditions that high blood pressure causes.  Appropriate allocation of resources to patients who actually have hypertension is supremely important. Repeated visits to treat uncontrolled hypertension, in my experience, leads to very high medication costs, higher incidence of medication side effects and, of course, frustration for both doctor and patient. If blood pressure control is being determined by significantly inaccurate technique, some simple changes could potentially make a significant impact both in dollars spent and quality of outcome.

So, you may ask, why not just do it right, all the time? A valid question. Not a year passes without some concentrated attempt by organizations such as the American Heart Association to re-educate us in the proper measurement of blood pressure.  Still, the constraints of being in a hurry (I think that trumps ignorance in its importance) continues to result in blood pressure measurements being done badly. The consequences of this are moderately important to each individual diagnosed with hypertension, and have a profound effect at the level of our whole population.

1 comment:

Martin @ Hipertension said...

There are variety of factors which can cause high blood pressure, the important thing is to identify it as soon as possible. As per my knowledge we cannot cure completely hypertension but can get in control. Exercising on the daily basis at least for half an hour, favorite physical activities like dancing, playing football, hockey etc.

- Martin, Hipertension Advocator