NEW ORLEANS — “Masked hypertension,” thought to affect about one in eight persons, can be identified through repeated office blood pressure measurements in those who show discrepancy between office and home blood pressure levels, according to Italian investigators.
“We were able to diagnose masked hypertension by using repeated office measurements. It matches what our patients found in home monitoring,” said principal investigator Dr. Giuseppe Crippa of Guglielmo da Saliceto Hospital, Piacenza, Italy.
Masked hypertension is defined as normal office BP but high ambulatory or home BP. The condition is thought to be as prevalent as white-coat hypertension and is often missed in clinical practice, said Dr. Crippa at the annual meeting of the American Society of Hypertension.
His study compared the level of agreement between office blood pressure (OBP), repeated office blood pressure (ROBP), and daytime ambulatory blood pressure (ABP) in 48 pharmacologically untreated patients with normal OBP (less than 140/90 mm Hg) but elevated daytime ABP (at least 135/85 mm Hg).
Since ABP averages multiple measurements, it is the accepted standard for diagnosing masked hypertension. For follow-up, home BP measurement is regarded as a simpler, reliable, and cost-effective alternative, he said.
OBP values were derived from the average of at least three sphygmomanometric measurements obtained during at least three separate visits, over a 3-week period. ABP values were calculated as the average of daytime readings taken every 15 minutes and nighttime readings obtained every 30 minutes. ROBP was performed after 20 minutes of rest with the patient seated comfortably alone; 10 consecutive measurements were taken every 2.5 minutes, with the average of the final six readings considered the final value.
The average blood pressure varies highly over 20 consecutive measurements, Dr. Crippa noted. For example, in one patient, the initial reading taken at 8:02 a.m. was 210/121 mm Hg and pulse rate was 96 bpm; midway through the ROBP it dropped to 140/79 mm Hg and 80 bpm; and concluded at 137/77 mm Hg and 72 bpm.
In the study, the OBP readings (both systolic and diastolic) were slightly but significantly lower than those achieved with ABP or ROBP. The differences between OBP and both ABP and ROBP were statistically significant. The ABP and ROBP readings were not significantly different and, in fact, were highly correlated with each other, Dr. Crippa reported.
With ABP as a reference for the diagnosis of masked hypertension, ROBP failed to identify this condition in just 2 out of the 48 patients.
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