IIRC there's also a Samsung Galaxy Watch that does blood pressure monitoring, with similar requirements. Have to work a bit to get the app installed in the US, but then it takes periodic measurements, is fairly accurate, and requires calibration once a month.
I was really hoping Apple was going to bring BP to the watch this year, but my guess is the regular external calibration requirement is too much for their plug-and-play philosophy.
+1. I also use Samsung Galaxy Watch (Active2) and find it to work well for me. I'm surprised more people don't know about it. I know couple of people that suffer from high BP. They showed little interest when I told them about the watch.
Regular external calibration helped me build confidence. I was suspicions if the watch worked, and how well it worked. Calibration is every month - it expires. I take 3 measurements in parallel watch-cuff, and tell the watch App what the cuff measured. I didn't mind it initially. I now find it annoying tbh. I see why Apple would like to get rid of it. Post calibration, I measure 3 times in parallel both watch and cuff to check if they match. If the difference is within 5% - then fine. In 3 years it's happened twice where they differed more and I had to recalibrate. From recollection - both times with a reason, a TV was turned on in living room.
I have the impression that BP measurements differ though the day (lower in the morning, higher in the evening), depending on activity or at rest of course, I think there maybe some seasonality too (winter v.s. summer). Measuring BP when going to the doctor once a year strikes me as a wholly inadequate. If the BP is absurdly high out of normal range - then yeah, we learn something is wrong with the patient. But in any other case - don't see what can be deduced from 1 random measurement.
To check if the calibration is important, I had my wife use the watch, that is calibrated on me. She got absurd readings. So yes - the calibration is important and is tied to the person that did the calibration. (edited to add this)
Most people don’t know about this feature on the galaxy watch because it’s only approved in certain countries, though you can hack the SHM to enable it.
I was really hoping Apple was going to bring BP to the watch this year, but my guess is the regular external calibration requirement is too much for their plug-and-play philosophy.