[Prevalence of masked hypertension in a cohort of controlled hypertensive patients in Spain]

Introduction and objective: In recent years the evidence that masked hypertension is associated with a highest cardiovascular risk is well established. Knowing the prevalence of masked hypertension in our country will allow a better cardiovascular risk stratification and management of hypertensive patients, although the information is scant and heterogeneous. For this reason, the working group for the study of masked hypertension (ESTHEN) in Spain developed the present study with the objective to know the prevalence of masked hypertension in a cohort of hypertensive patients follows in several Hypertension Units in Spain.

Patients and methods: Prospective study of a cohort of hypertensive patients followed in 75 Hypertension Units in Spain. Eligible patients were hypertensive cases aged ≥ 18 years receiving antihypertensive drug treatment and showing an adequate BP control at the clinic (BP < 140/90 mmHg). Masked hypertension was defined when mean daytime BP ≥ 135/85 mmHg.

Results: We analyzed data from 302 patients. Mean age was 56.2 years and 56% were male. Prevalence of masked hypertension was 48% (95%CI 42-53). The most prevalent accompanying risk factors were abdominal obesity (39.7%), smoking (24.2%), family with premature cardiovascular disease (22.5%), and diabetes (11.6%). Prevalence of left ventricular hypertrophy was 23.8%, and 22.2% of patients had established cardiovascular disease, and 6.3% had renal disease. Masked hypertension was related to the absence of established cardiovascular disease (OR 0.306, 95%CI 0.139-0.676) and to the proximity of the clinic BP levels to the control thresholds (0.901, 95%CI 0.842-0.963). The OR of masked hypertension diminished 10% for each mmHg below the threshold of control.

Conclusions: The prevalence of masked hypertension was approximately 50% in treated hypertensive patients. ABPM constitutes a basic tool for detection of this abnormality.