How should we measure blood pressure? Implications of the fourth blood pressure measurement in office blood pressure

Abstract

According to the European Hypertension Guidelines regarding office blood pressure measurements (OBPMs), the mean between second/third or third/fourth OBPM should be taken if the first two readings differ by ≤10 or >10 mmHg, respectively. Our aim was to explore the value of the fourth OBPM and determine whether a simplified OBPM procedure is feasible without loss of quality. In this cross-sectional study, four standard OBPMs were taken. The mean of the second/third OBPM (S2S3/D2D3) and third/fourth OBPM (S3S4/D3D4) for systolic/diastolic values was calculated. Correlation, agreement, and differences regarding BP classification were explored for the entire cohort and subsets with a difference between the first/second OBPM (S1S2/D1D2) ≤10 and >10 mmHg. Overall (n = 802) and for the subsets with an S1S2 (n = 596) and D1D2 (n = 742) difference ≤10 mmHg, S3S4/D3D4 was in median 0.5 mmHg lower than S2S3/D2D3, respectively (p < .0005 for all). In participants with an S1S2 (n = 206) and D1D2 (n = 60) difference >10 mmHg, S3S4/D3D4 differed numerically from S2S3/D2D3, respectively (p > .1 for all). Overall and for all subsets with an S1S2/D1D2 difference ≤10/>10 mmHg, less subjects were numerically classified as hypertensive with S3S4/D3D4 than with S2S3/D2D3 (p > .04), but BP reclassification occurred in both directions in 1.0%-10.0%, depending on the cohort. In conclusion, the third/fourth OBPM results in lower BP values than the second/third measurement, regardless of the difference between first/second OBPM, whereby BP reclassifications occurred in both directions. Therefore, the cutoff of >10 versus ≤10mmHg difference between first/second OBPM to implement a fourth BPM harbors the risk of distorted results. We therefore recommend using the second/third BPM for standardized OBPM. Trial registration: Registered on clinicaltrials.gov (NCT02552030).

Keywords: European Society of Cardiology; European Society of Hypertension; arterial hypertension; blood pressure; blood pressure classification; blood pressure measurements; guidelines; office blood pressure.

© 2020 The Authors. The Journal of Clinical Hypertension published by Wiley Periodicals LLC.

Figures

FIGURE 1

Procedure for calculation of BP values and labeling according to ESH: panel A: Difference between the first and second OBPMs >10 mmHg; panel B: difference between the first and second OBPMs ≤10 mmHg

FIGURE 2

Bland‐Altman plots comparing the difference between S3S4 and S2S3 (panels A–C) and D3D4 and D2D34 (panels D–F). Displayed are comparisons of S3S4 and S2S3 for the entire cohort (panels A), for participants with an absolute S1S2 difference >10 mmHg (panel B), for participants with an absolute S1S2 difference ≤10 mmHg (panel C), comparisons of D3D4 and D2D3 for the entire cohort (panel D), for participants with an absolute D1D2 difference >10 mmHg (panel E), and for participants with an absolute D1D2 difference ≤10 mmHg (panel F)

FIGURE 3

BP classifications in % for systolic (panel A) and diastolic (panel B) BP values. Dark green: S2S3/D2D3 and S3S4/D3D4 classified as normotensive; light green: corresponding S2S3/D2D3 and S3S4/D3D4 classified as hypertensive; red: S2S3/D2D3 classified as normotensive and corresponding S3S4/D3D4 classified as hypertensive; and orange: S2S3/D2D3 classified as hypertensive and corresponding S3S4/D3D4 classified as normotensive. S1S2: absolute difference between first and second systolic blood pressure measurements. D1D2: absolute difference between first and second diastolic blood pressure measurements. BP: blood pressure