Discrepancies in office blood pressure measurement protocols across international guidelines: "Houston, we've got a problem.".

Office blood pressure (OBP) remains a cornerstone of hypertension management. However, contemporary hypertension guidelines recommend different OBP measurement protocols, which vary in procedural details and analytical approaches, and the clinical implications of these differences remain unclear. We compared eight guideline-recommended OBP protocols (Japanese, Korean, ISH, NICE, ESC/Brazilian, ESH, Chinese, and ACC/AHA) in 826 treated hypertensive outpatients (age = 60.2 ± 14.3 years; 40.4% men) from two Brazilian cohorts, using aneroid ( n  = 394) and oscillometric devices ( n  = 432). OBP was assessed with consecutive 1-min readings and guideline-specific algorithms. Mean systolic/diastolic OBP and uncontrolled hypertension were analyzed using repeated measures. Systolic OBP differed by up to 2.8 mmHg across protocols, while the prevalence of uncontrolled hypertension ranged from 30.0 to 41.3% using the less than 140/90 mmHg threshold and from 60.8 to 70.6% using the less than 130/80 mmHg threshold. In conclusion, guideline-recommended OBP protocols yield clinically meaningful differences, limiting their interchangeability and highlighting the need for protocol standardization before defining optimal OBP targets.