Key result
The mean of the third and fourth office blood pressure measurements resulted in values that were a median of 0.5 mmHg lower than the second and third measurements (p < 0.0005), leading to arbitrary blood pressure reclassifications.
Why the study?
European guidelines recommend taking a fourth office blood pressure measurement if the first two readings differ by >10 mmHg, but the value of a fourth reading and the feasibility of a simplified procedure remained unclear.
Does calculating office blood pressure using the third and fourth measurements compared to the second and third measurements change blood pressure values and hypertension classification in adult patients?
Cross-Sectional (n=802)
No
Does calculating office blood pressure using the third and fourth measurements compared to the second and third measurements change blood pressure values and hypertension classification in adult patients?
Mean Difference: -0.5
Absolute Event Rate: 122% vs 123%
p-value: p=<0.0005
Using the third and fourth office blood pressure measurements yields systematically lower values than the second and third, risking misclassification and supporting the universal use of the second and third measurements.
Office BP sequence may alter classifications; leaves open optimal protocols for consistent hypertension diagnosis.
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).
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Vischer et al. (2020) conducted a cross-sectional in Arterial hypertension / Blood pressure measurement (n=802). Mean of third and fourth office blood pressure measurements (S3S4/D3D4) vs. Mean of second and third office blood pressure measurements (S2S3/D2D3) was evaluated on Difference in systolic blood pressure (Median difference -0.5 mmHg, p=<0.0005). The mean of the third and fourth office blood pressure measurements resulted in values that were a median of 0.5 mmHg lower than the second and third measurements (p < 0.0005), leading to arbitrary blood pressure reclassifications.
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