Algorithm for diagnosing hypertension using out-of-office blood pressure measurements

Association of the magnitude of the difference in blood pressure between office and ambulatory measurements with blood pressure variability in untreated individuals

OBJECTIVES

We evaluated the association between cardiovascular risk factors and the magnitude of the difference in systolic blood pressure (SBP) between office and ambulatory measurements (masked effect) in untreated individuals without apparent hypertension-mediated organ damage (HMOD).

METHODS

The inclusion criteria were 1) age ≥ 20 years, 2) blood pressure ≥ 140/90 mmHg at the outpatient clinic, and 3) not receiving antihypertensive medications. The difference between office and ambulatory SBP was calculated by subtracting the ambulatory daytime SBP from the office SBP. The association between the masked effect and SBP variability was analyzed in individuals without HMOD (no electrocardiographic left ventricular hypertrophy, spot urine albumin-to-creatinine ratio < 30 mg/g, and estimated glomerular filtration rate ≥ 60 mL/min/1.73 m², n = 296).

RESULTS

Among the cardiovascular risk factors, ambulatory BP variability was significantly correlated with the SBP difference. The standard deviation (SD) and coefficient of variation (cv) of 24-h SBP exhibited a significant negative linear association with the SBP difference in univariate and multivariate analyses adjusted for age, sex, presence of diabetes, and 24-h ambulatory SBP. A significant association was observed in patients with ambulatory daytime hypertension. In the multivariate analysis, individuals with a negative SBP difference > -5 mmHg exhibited a higher SD and cv of 24-h SBP than those with a negative SBP difference ≤ -5 mmHg or a positive SBP difference.

CONCLUSIONS

The results of our study suggest that the magnitude of the negative difference in office and ambulatory SBP may be a potential risk factor, even in individuals without apparent HMOD.

TRIAL REGISTRATION

This trial is registered with ClinicalTrials.gov ( NCT03855605 ).

Algorithm for diagnosing hypertension using out-of-office blood pressure measurements

The authors developed and validated a diagnostic algorithm using the optimal upper and lower cut‐off values of office and home BP at which ambulatory BP measurements need to be applied. Patients presenting with high BP (≥140/90 mm Hg) at the outpatient clinic were referred to measure office, home, and ambulatory BP. Office and home BP were divided into hypertension, intermediate (requiring diagnosis using ambulatory BP), and normotension zones. The upper and lower BP cut‐off levels of intermediate zone were determined corresponding to a level of 95% specificity and 95% sensitivity for detecting daytime ambulatory hypertension by using the receiver operator characteristic curve. A diagnostic algorithm using three methods, OBP‐ABP: office BP measurement and subsequent ambulatory BP measurements if office BP is intermediate zone; OBP‐HBP‐ABP: office BP, subsequent home BP measurement if office BP is within intermediate zone and subsequent ambulatory BP measurement if home BP is within intermediate zone; and HBP‐ABP: home BP measurement and subsequent ambulatory BP measurements if home BP is within intermediate zone, were developed and validated. In the development population (n = 256), the developed algorithm yielded better diagnostic accuracies than 75.8% (95%CI 70.1–80.9) for office BP alone and 76.2% (95%CI 70.5–81.3) for home BP alone as follows: 96.5% (95%CI: 93.4–98.4) for OBP‐ABP, 93.4% (95%CI: 89.6–96.1) for OBP‐HBP‐ABP, and 94.9% (95%CI: 91.5–97.3%) for HBP‐ABP.  In the validation population (n = 399), the developed algorithm showed similarly improved diagnostic accuracy. The developed algorithm applying ambulatory BP measurement to the intermediate zone of office and home BP improves the diagnostic accuracy for hypertension.