P-26: Factors infuencing the difference between clinic and ambulatory blood pressure measurements in untreated patients with essential hypertension

• Published in: American journal of hypertension 2004-05, Vol.17 (S1), p.42A-42A
• Main Authors: Hermida, Ramon C., Ayala, Diana E., Calvo, Carlos, Dominguez, Maria J., Covelo, Manuel, Fontao, Maria J., Soler, Rita, Lopez, Jose E.
• Format: Article
• Language: English
• Subjects: ABPM; Clinic Blood Pressure; White Coat Effect
• ISSN: 0895-7061; 1941-7225; 1879-1905
• DOI: 10.1016/j.amjhyper.2004.03.100

Ambulatory blood pressure (BP) monitoring (ABPM) avoids most of the limitations of conventional BP values. Clinic BP values are frequently biased by the transient rise of a patient's BP in response to the clinical surroundings or the presence of the observer (the “white coat” effect, WCE). The difference between clinic and diurnal ABPM measurements has been frequently used as an estimate of the WCE. Some reports have indicated that this effect is larger in women and the elderly, although the potential factors influencing the WCE are still under investigation. Accordingly, we investigated potential markers of the WCE in untreated hypertensive patients. We analyzed 1200 ABPM series from 837 untreated patients with grade 1–2 essential hypertension (408 men and 429 women), 49.5±13.5 years of age. ABPM was performed at 20-min intervals from 07:00 to 23:00 hours and at 30-min intervals at night for 48 consecutive hours. Physical activity was simultaneously monitored every minute by wrist actigraphy, and the information used to determine diurnal and nocturnal means of BP for each patient according to individual resting time. Conventional office BP measurements (6 per study visit just before starting ABPM) were obtained with a validated automatic oscillometric device. A model for the WCE was obtained by multiple regression analysis, using as potential predictors age, height, weight, body mass index (BMI), waist and hip perimeters, gender, smoking, the day/night BP ratio (obtained for each BP profile as the percent decline in the nocturnal relative to the diurnal BP mean), and the number of ABPM sessions performed on the same patients. Results indicate a significant positive correlation between the WCE and gender (larger in women), age, BMI, hip perimeter, and a very strong negative correlation with the day/night ratio (P