Clinical implications of white coat hypertension: an ambulatory blood pressure monitoring study

Within routine clinical practice, white coat hypertension (where blood pres sure is persistently higher in the presence of the doctor or nurse but norm al outside the medical setting) makes the diagnosis and management of hyper tension difficult. There are conflicting data regarding the prevalence and significance of white coat hypertension. This study has used ambulatory blo od pressure monitoring to detect the presence of white coat hypertension in 186 patients referred to an out-patient hypertension unit. The presence of white coat hypertension was defined as an average office blood pressure (m easured on three occasions over a 2-month period) of >140/90 mm Hg and an a mbulatory awake blood pressure less than or equal to 136/86 mm Hg. The prev alence of white coat hypertension in those patients with borderline hyperte nsion (diastolic blood pressure 90-99 mm Hg) and those with mild-to-moderat e hypertension (diastolic blood pressure greater than or equal to 100 mm Hg ) was determined, Echocardiography was used to assess left Ventricular mass index in patients with and without white coat hypertension. The prevalence of white coat hypertension in the total group was 23%, However, the preval ence was higher (33%) in those patients with borderline hypertension compar ed to 9% of those patients with mild-to-moderate hypertension. There was a statistically significant increase in left ventricular mass index in patien ts with no evidence of white coat hypertension (125 gm/m(2)) compared to th ose with white coat hypertension (102 gm/m(2)). We conclude that, if office blood pressure is used to identify patients with hypertension who may requ ire treatment, some patients will be incorrectly diagnosed and may be treat ed inappropriately. We recommend that ambulatory blood pressure monitoring is used in the routine assessment of ail newly diagnosed hypertensive patie nts. Furthermore, we recommend echocardiography in patients with borderline hypertension as some will already have an increased left ventricular mass index.