November 7, 2018Open Access
View Full PaperComparison of automated clinical and research blood pressure measurements: Implications for clinical practice and trial design
Key Result
Standardized automated clinic blood pressure measurements were higher by 4.4/3.8 mm Hg (P=0.007/<0.001) and more variable than research measurements, potentially halving power in trials.
Study Design
Type
Observational
Multicenter
No
Structured PICO
Does standardized automated clinic blood pressure measurement differ from research blood pressure measurement?
P
Population
Patients with blood pressure measurements from both a primary care clinic and a randomized trial conducted at the same site
I
Intervention
Standardized automated clinic blood pressure measurement
C
Comparator
Research blood pressure measurement from a randomized trial
O
Outcome
Concordance between clinic and research blood pressure measurementssurrogate
Standardized automated clinic BP measurements are higher and more variable than research BP measurements, which could lead to overtreatment if research-based targets are applied in clinical practice.
Main Result
Effect estimate: Difference 4.4/3.8 mm Hg
p-value: p=0.007/<0.001
Abstract
Discrepancies between clinic and research blood pressure (BP) measurements lead to uncertainties in translating hypertension management guidelines into practice. We assessed the concordance between standardized automated clinic BP, from a primary care clinic, and research BP, from a randomized trial conducted at the same site. Mean single-visit clinic BP was higher by 4.4/3.8 mm Hg (P = 0.007/<0.001). Concordance in systolic BP (SBP) improved with closer proximity of measurements (difference = 2.5 mm Hg, P = 0.21 for visits within 7 days), but not averaging across multiple visits (difference =5.1(9.2) mm Hg; P < 0.001). This discrepancy was greater among female participants. Clinic-based difference in SBP between two visits was more variable than research-based change (SD = 19.6 vs 14.0; P = 0.002); a 2-arm trial using clinic measurements would need 95% more participants to achieve comparable power. Implementation of a bundled standardization intervention decreased discrepancies between clinic and research BP, compared to prior reports. However, clinic measurements remained higher and more variable, suggesting treatment to research-based targets may lead to overtreatment and using clinic BP approximately halves power in trials.