The validity of a daytime ambulatory blood pressure to diagnose masked hypertension.

Masked hypertension (MH) is traditionally diagnosed with 24-hour ambulatory blood pressure monitoring (24-ABPM). This is relatively costly and could cause discomfort during the night. We studied the validity of daytime ABP (DT-ABPM) in young National Guard soldiers and determined the prevalence in comparison to the standard 24-ABPM. A prospective study of 196 soldiers aged 21-50 years, without a history of hypertension or antihypertensive medication use. Each participant was fitted with a 12h-ABPM. Patients were diagnosed with MH if the office blood pressure (OBP) was <140/90 mmHg and the average DT-ABPM was ≥135/85 mmHg. By pairing the average OBP with the 12 h-ABPM, the prevalence of MH was estimated as 18/196 (9.2%), the SBP MH (systolic blood pressure) of 8.2% and the DPB MH (diastolic blood pressure) of 3.1%.  When we compared the daytime prevalence with the 24 h-ABPM, and the average OBP, the prevalence of MH was 29/196 (14.8%). No statistically significant difference was noted (kappa=0.74; 95% CI: 0.59 to 0.88). We conclude that DT-ABPM is a good method and convenient to detect MH, with no statistically significant difference when compared to the 24 h-ABPM. The prevalence of MH in young healthy soldiers was unexpectedly high.