What's your systolic blood pressure? The answer may depend on whether the reading is taken in your upper arm or wrist. Researchers have found the variation to be as large as 20 mmHg in 14 percent of the people tested. On average, a reading taken in the radial artery at the wrist was 5.5 mmHg higher than that taken in the brachial artery on the bicep. This could have implications for who is given anti-hypertension drugs, the authors said online March 25, 2019, in Hypertension.