White-coat effect in African-American hypertensives.

To evaluate the white-coat effect in African-American patients attending a primary care clinic in Waterbury, Connecticut we measured clinic and ambulatory BP in patients who had an office systolic BP > 140 mmHg or diastolic BP > 90 mmHg. Clinical observers included 1) the referring physician, 2) a black male study physician, 3) a white male study physician similar in age and experience to the black physician, and 4) a female, white nurse. With the exception of the referring doctor, the order of duplicate, seated, and blinded BPs taken in the clinic were randomized to avoid an ‘order’ effect. The white-coat effect (observer BP - awake ambulatory BP) for the various observers are shown in the Table (n = 23). Two patients (8.6%) had ambulatory BPs that were clearly normotensive despite hypertensive values by the referring physician, however, one of these patients had borderline hypertensive values while asleep. Thus, only one (4.3%) patient would be characterized as having white-coat hypertension. Our preliminary data suggest that while there is a substantial white-coat effect based on the referring doctorʹs office BP, the prevalence of patients with normal ambulatory BPs (i.e., a true white-coat hypertensive) may be lower than the 15-30% values that have been observed in the non-Black patient population.