Repeated automated versus daytime ambulatory blood pressure measurement in mild, moderate and severe untreated black hypertensive patients.
OBJECTIVE: To examine the extent to which one session of repeated automated (30-45 min) blood pressure measurements in non-treated, hypertensive patients can be used to predict daytime ambulatory blood pressure (ABP). METHODS: Two hundred untreated black hypertensive patients (mean age 50.2+/-11.2) were retrospectively stratified on the basis of the daytime ambulatory diastolic blood pressure (DBP) into mild, moderate and severe hypertensives (90 mmHg <DBP < 140 mmHg). Office blood pressure was determined at 3 min intervals for a total of 30-45 min using the Dinamap Critikon 1846 SX monitor. Twenty-four hour ambulatory blood pressure (ABP) was performed on the same day in all patients using a SpaceLabs 90207 device. RESULTS: The mean diastolic Dinamap measurements compared with the mean ambulatory daytime DBP were very similar in terms of 'traditional' statistics (mean: 114 +/- 14.6 versus 113 +/- 12 mmHg, correlation: 0.80). However, agreement analysis according to Bland and Altman showed a poor agtreement with an error as high as 19 mmHg. The mean systolic Dinamap measurements compared with the mean ambulatory daytime SBP were significantly overestimated (mean: 185 +/- 25.0 versus 170 +/- 19.3 mmHg, correlation 0.82) and the error was as high as 43 mmHg. On residual analysis, 75% of the diastolic Dinamap values and only 35% of the systolic Dinamap measurements were within an error of +/- 10 mmHg. The average of the first five Dinamap measurements had the greatest predictive ability for the daytime ABP. CONCLUSION: As a result of the poor agreement between the two methods, we suggest that, from the clinical point of view, the two techniques should be treated as two separate entities.
Mueller
UK
Division of Cardiology, Baragwanath Hospital, University of the Witwatersrand, Johannesburg, South Africa.
Wells
M
Radevski
I
Ouwerkerk
J
Tager
R
Sliwa
K
Sareli
P