Threshold for diagnosing hypertension by automated office blood pressure using random sample population data.

OBJECTIVE

Manual office blood pressure (BP) is still recommended for diagnosing hypertension. However, its predictive value is decreased by errors in measurement technique and the white-coat effect. The errors can be eliminated by automated office BP (AOBP) measurement taking multiple readings with the participant resting quietly alone. Therefore, use of AOBP in clinical practice requires a threshold value for hypertension diagnosis. The aim of the present study was to determine an AOBP threshold corresponding to the 140/90 mmHg manual office BP using data from a large random population sample.

METHODS

In 2145 participants (mean age 47.3 ± 11.3 years) randomly selected from a Brno population aged 25-64 years, BP was measured using manual mercury and automated office sphygmomanometers.

RESULTS

Manual SBP (mean difference 6.39 ± 9.76 mmHg) and DBP (mean difference 2.50 ± 6.54 mmHg) were higher than the automated BP. According to polynomial regression, automated systole of 131.06 (95% confidence interval 130.43-131.70) and diastole of 85.43 (95% confidence interval 85.03-85.82) corresponded to the manual BP of 140/90 mmHg. Using this cut-off, the white-coat hypertension was present in 24% of participants with elevated manual BP, whereas 10% had masked hypertension and 11% masked uncontrolled hypertension. In individuals with masked uncontrolled hypertension, only AOBP was associated with the urinary albumin-creatinine ratio, whereas there was no association with manual BP.

CONCLUSION

AOBP of 131/85 mmHg corresponds to the manual BP of 140/90 mmHg. This value may be used as a threshold for diagnosing hypertension using AOBP. However, outcome-driven studies are required to confirm this threshold.