SAN FRANCISCO — You may not need to send patients with suspected “white coat hypertension” home with an ambulatory blood pressure monitor. Automated repeat measurements that are performed in the office work just as well for ruling out this type of hypertension, Giuseppe Crippa, M.D., said at the annual meeting of the American Society of Hypertension.
In a study of 122 patients, measurements from an automated, in-office oscillometric device that obtained 10 valid blood pressure readings matched ambulatory blood pressure measurements closely enough that the in-office readings identified 40 out of 41 patients with white coat hypertension, said Dr. Crippa of Guglielmo da Saliceto Hospital, Piacenza, Italy.
The study included consecutive patients who were referred to the hospital's hypertension unit to confirm or rule out suspected hypertension. All patients had clinic readings above 140/90 mm Hg, but reported measurements at home that were consistently below 140/90 mm Hg.
For each patient, in-office blood pressures were taken by a physician, a nurse, and the automated device (in random order) and compared with ambulatory blood pressure measurements. The doctor and nurse each took three readings after the patient had rested for 20 minutes. The automated repeat measurements were taken at 2.5-minute intervals with the patient sitting alone in a clinic room. Investigators compared the average of the last two measurements taken by the doctor and nurse with the average of the last five measurements by the automated device and the mean daytime ambulatory blood pressure.
Blood pressures taken by doctors and nurses were significantly higher than daytime ambulatory measurements. The automated and ambulatory measurements closely overlapped, however, with no significant differences between them, he said.
Doctor's measurements averaged 15/11 mm Hg higher, and nurses' measurements averaged 11/9 mm Hg higher, than daytime ambulatory blood pressures. Only 1 of 41 patients who were normotensive on daytime ambulatory monitoring had hypertension on automated in-office testing.
Automated repeat office blood pressure measurements “could be a substitute for home blood pressure monitoring,” he said.
Hypertension was defined as blood pressures above 132/85 mm Hg. Conventional measurements by physicians in the office can be inaccurate because of variable reactions by the patients (white coat hypertension) and errors in technique. This can lead to an overestimate of hypertension, incorrect diagnoses, and inappropriate treatment, Dr. Crippa said.
The study shows that white coat hypertension also occurs when nurses take the measurements, he noted.
Average systolic blood pressure readings in the 41 patients with white coat hypertension were 137 mm Hg by doctors' measurements, 133 mm Hg by nurses, 123 mm Hg by the automated device, and 121 mm Hg on ambulatory daytime monitoring. Ambulatory monitoring took place between 7 a.m. and 5 p.m.
Average diastolic blood pressure readings in patients who had white coat hypertension were 86 mm Hg when taken by doctors, 83 mm Hg by nurses, 75 mm Hg by the automated device, and 73 mm Hg by ambulatory monitoring.