PHWR Public Health Weekly Report

Resistant hypertension has a high risk of end-stage renal disease, cardiovascular disease, and death, so it is important to detect resistant hypertension properly and actively control blood pressure (BP). BP can be diagnosed based on office blood pressure, but, when the readings are inaccurate due to certain environments, many patients are classified as white-coat uncontrolled hypertension or masked uncontrolled hypertension with ambulatory BP monitoring. Therefore, it is recommended to use ‘out-of-office’ BP monitoring, such as an active blood pressure test, to determine an appropriate treatment policy for resistant hypertension. Still, this convention is not fully utilized in clinical practice. The objective of this study was to compare the diagnostic accuracy of office BP thresholds of 140/90 and 130/80 mmHg to correctly identify uncontrolled out-of-office BP in resistant hypertension. As a multicenter study conducted in Korea, the results of 468 patients enrolled in the resistant hypertension cohort were analyzed. Office BP, home BP, and ambulatory BP were measured at baseline. Resistant hypertension was defined as office BP ≥ 130/80 mmHg with three different classes of antihypertensive medications, including thiazide-type/like diuretics or treated hypertension with four or more different classes of antihypertensive medications. Uncontrolled out-of-office BP was defined as daytime BP ≥ 135/85 mmHg and/or home BP ≥ 135/85 mmHg. For the diagnosis of uncontrolled out-of-office BP, the accuracy of an office blood pressure of 140/90 mmHg was 60.9%, but the accuracy of an office blood pressure of 130/80 mmHg was 74.1%. When the office BP threshold was changed from 140/90 mmHg to 130/80 mmHg, the net reclassification index for the diagnosis of BP outside the uncontrolled office was 0.543. When the office BP threshold was lowered, the proportion of patients with masked uncontrolled hypertension that were easily neglected to treat decreased. In conclusion, an office BP of 130/80 mmHg can be more accurately classified as uncontrolled out-of-office BP than as office BP 140/90 mmHg and lowering the office BP threshold can be helpful for controlling BP in resistant hypertension.

Key words Resistant hypertension, Office blood pressure, Out-of-office blood pressure, Hypertension phenotypes

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