And told me to get a home unit, and bring it in to test it. His assessment differed from this in that he said that "most home blood pressure monitors are accurate". I brought in mine, the nurse tested it, and said it was accurate. The readings weren't 100% the same as what she got, but then they normally vary second to second anyhow.
Also of note is that she was much more careful with the test when testing my unit as opposed to normal. For both their and my unit she had me sit quiet and still, she made sure to place the cuff in the same place, and she took the reading slowly on their manual unit. On a normal physical she places the cuff over my shirt and and drops the pressure quite fast.
Now I would guess this is because they aren't that worried. My BP is normal to the high end of normal, but is normal, when measured at home and is on the high end of normal up to just at the bottom of the pre-hypertension range at the office. So I would guess she's not that concerned with having it right down to the mmHg, with in 10 is probably good enough. If it hasn't changed much since last time, no need to worry and no need to spend a bunch of time being super precise.
Now maybe my doctor is just lax and stupid, but he doesn't seem that way (and his background.credentials don't indicate that). However maybe this journal has a bit of a bias in wanting to over-diagnose hypertension and/or push that physician measurements are the One True Way(tm).
To me it seems silly to worry about 5% or less error on a test like this. The fact that BP ranges neatly line up on clear decimal lines should tell you that the specific numbers are guidelines only, not maxims. It isn't like the did some measurements and said "My god at precisely 140mmHg blood pressure becomes unhealthy and at precisely 120mmHg it becomes a complete non-factor!" Of course not, rather based on medical knowledge they established the normal, pre-hypertension, hypertension, and hypertensive crisis ranges and set them along base 10 boundaries because we like that.
It is a guide to trained professionals, not a stress point past which there is a sudden failure. Your doctor isn't going to treat it radically different if your BP is 141/91 vs 137/89. They'll evaluate what kind of treatment (if any) they think you should have based on a number of factors about you.