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Comment by hirvi74 | Hacker News Reader

> This is why you do readings three different times a day for several days.

What good is this if my monitor is not as accurate as the one at a doctor's office? It's not like my doctor would take my monitor's readings over his.

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Find one that is accurate enough and crosscheck it with the one at the doctor by taking regular measurements so you get an idea of trends rather than absolute values. Doctors do know about white coat hypertension - it's not a myth. There's no reason you can't do your own experiments with consumer-level blood pressure monitors from reputable manufacturers. In fact, it was my mother's primary care provider who recommended she buy one for home use.

This is what I did with a US$10 pulse oximeter (a Contec CMS50M from China) when my dad ended up in ICU last year, and it was pretty much bang-on with its readings. I've also tested my pulse oximeter on plane trips and know it will drop below 90% when the air is thin (and rise up again if I do some deep breathing), and therefore know it isn't always stuck at a high value.

Search PubMed for "The Accuracy of 6 Inexpensive Pulse Oximeters Not Cleared by the Food and Drug Administration: The Possible Global Public Health Implications".

You might be surprised. "White coat hypertension" is well-known. Someone with a reliable set of readings from home would be more convincing than someone who says "I get it read at Walmart/CVS once a month and it's ok".

Your doctor's office's monitor isn't incredibly accurate. If you want accurate, you need a mercury sphygmomanometer to measure the pressure. Unless fundamental properties of the universe have changed, it will also be comparable to any other readings taken with mercury.

And it has to be in retrograde.

That's a complicating factor, but one that we can usually calculate.

My doctor did. My blood pressure was slightly elevated in his office and I said it happens at every doctor. He said to get a home monitor, test 3 times in the morning, 3 times in the afternoon for a week and bring in the results at the next appt.

Don't worry, your monitor is good enough for the purpose of screening for hypertension. Truth is the exact values don't matter much for this purpose. Only thing that matters is the fact that people die less and develop less complications when treated based on the results. They are still useful even if the figures have some error in them.

Medicine is just statistics.

It varies of cause, but here the doctor just sends you home with a monitor exactly identical to the one they use at the office. But it’s not like there’s a world of difference to the ones you could buy yourself at a resonable cost.

Either it's accurate enough (most cases) or it is too wrong

Unless it's a wrist model, it should be ok.

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