Clinical features and predictors of masked uncontrolled hypertension from the Korean Ambulatory Blood Pressure Monitoring Registry

Abstract

Background/aims: The clinical characteristics of patients with masked uncontrolled hypertension (MUCH) have been poorly defined, and few studies have investigated the clinical predictors of MUCH. We investigated the demographic, clinical, and blood pressure (BP) characteristics of patients with MUCH and proposed a prediction model for MUCH in patients with hypertension.

Methods: We analyzed 1,986 subjects who were enrolled in the Korean Ambulatory Blood Pressure Monitoring (Kor-ABP) Registry and taking antihypertensive drugs, and classified them into the controlled hypertension (n = 465) and MUCH (n = 389) groups. MUCH was defined as the presence of a 24-hour ambulatory mean systolic BP ≥ 130 mmHg and/or diastolic BP ≥ 80 mmHg in patients treated with antihypertensive drugs, having normal office BP.

Results: Patients in the MUCH group had significantly worse metabolic profiles and higher office BP, and took significantly fewer antihypertensive drugs compared to those in the controlled hypertension group. Multivariate logistic regression analyses identified high office systolic BP and diastolic BP, prior stroke, dyslipidemia, left ventricular hypertrophy (LVH, ≥ 116 g/m2 for men, and ≥ 96 g/m2 for women), high heart rate (≥ 75 beats/min), and single antihypertensive drug use as independent predictors of MUCH. A prediction model using these predictors showed a high diagnostic accuracy (C-index of 0.839) and goodness-of-fit for the presence of MUCH.

Conclusion: MUCH is associated with a high-normal increase in office BP and underuse of antihypertensive drugs, as well as dyslipidemia, prior stroke, and LVH, which could underscore achieving optimal BP control. The proposed model accurately predicts MUCH in patients with controlled office BP.

Keywords: Blood pressure; Blood pressure monitoring, ambulatory; Masked uncontrolled hypertension.

Figure 1

Study population. ABPM, ambulatory blood pressure monitoring; BP, blood pressure; MUCH, masked uncontrolled hypertension; ROC, receiver operating characteristic. ^aAt least 20 recordings during wakefulness and seven recordings during sleep, after the exclusion of unmeasured recordings and recordings with extreme blood pressures (systolic BP ≥ 350 or < 60 mmHg; diastolic BP ≥ 250 or < 30 mmHg).

Figure 2

Prevalence of masked uncontrolled hypertension (MUCH) according to blood pressure levels. (A) MUCH was more frequent in patients with high systolic blood pressure (SBP) and diastolic blood pressure (DBP). However, when office SBP was ≥ 130 mmHg, the frequencies of MUCH were comparably high. (B) The frequencies of MUCH did not differ according to the number of antihypertensive drugs; however, when the SBP was ≥ 130 mmHg, the frequencies of MUCH decreased with increasing numbers of antihypertensive drugs.

Figure 3

Nomogram of the scoring system predicting for masked uncontrolled hypertension. SBP, systolic blood pressure; DBP, diastolic blood pressure; LVMI, left ventricular mass index.

Figure 4

Diagnostic performances and the goodness of fit of the score system predicting. (A) Receiver operating characteristic curve analysis showed that the score system showed good diagnostic performance for masked uncontrolled hypertension. (B) Hosmer-Lemeshow goodness-of-fit test. AUC, area under the curve; CI, confidence interval; PPV, positive predictive value; NPV, negative predictive value.