NEW ORLEANS— April 3, 2011 – White coat hypertension has been linked to pulse pressure, a new finding that may help doctors make better clinical decisions, researchers reported here today in a news conference at the American College of Cardiology’s 60th Annual Scientific Session and ACC.i2 Summit.
White coat effect (WCE) is blood pressure (BP) measured by a medical professional in a medical setting and tends to be elevated in comparison with BP measured by the patients themselves at home. The effect is well documented and results from anxiety and stress.
“Although earlier studies demonstrated that elevated systolic blood pressure is related to WCE, this is the first study to look at whether pulse pressure can help separate white coat hypertension from true hypertension,” reported Youngkeun Ahn, MD, National University Hospital, Gwangju, South Korea, who conducted the study Can Pulse Pressure Predict White Coat Effect in Treated Hypertensive Patients.
The study found that pulse pressure taken by physicians was positively correlated with WCE (r = 0.511, p < 0.001 in systole, r = 0.063 p = 0.037 in diastole).
“Although pulse pressure has been known to be a mechanical property of large arteries, it was also associated with WCE. Our findings suggest that pulse pressure measured by physician at clinic may predict the WCE, which may help control the treated hypertensive patients,” he said.
However, Ahn added, “there is evidence that white coat hypertension might signal that someone is at risk of developing high blood pressure in the future and may still need to be monitored.”
He estimated that white coat hypertension affects 20-50% of patients, “which may result in unnecessary treatment.”
WCH was found in 31% of patients, with pulse pressure was positively associated with systolic (p< 0.001) and diastolic WCE (p<0.001).
The Korean research team studied 1,087 outpatients with chronically treated hypertension from a university setting (57±10 years, female; 52%).
Subjects were taught how to measure BP and told to check it in the morning and evening for two weeks.
WCE was defined as a positive difference above 20mmHg in systolic or 10 mmHg in diastolic.The averages of WCE were 9.8±14.8 mmHg in systole and 3.4±9.2 mmHg in diastolic.
To determine if other factors may be in play, the study gathered data, including age, gender, potential vascular risk factors, target organ damage, systolic and diastolic BP, mean BP, and heart rate.There was no significant association with age and gender.
Other statistical associations included family history of premature cardiovascular disease (r = 0.061, p = 0.045 in systole, r = 0.079, p = 0.010 in diastole) and were positively correlated with WCE.
Diabetes mellitus (r = -0.066, p= 0.030 in systole, r = -0.076, p = 0.013 in diastole) and smoking (r = -0.068, p = 0.026 in systole, r = -0.069, p = 0.022 in diastole) were negatively correlated in WCE.
Target organ damages, including the heart, were also negatively associated with WCE (r = 0.095, p = 0.002 in systole, r = -0.089, p = 0.004 in diastole).
The study was funded by the Korean Institute of Medicine, Korea and Korea Healthcare Technology, R&D Project, Ministry of Health, Welfare & Family Affairs, and the Republic of Korea.