Parati G, Omboni S, Staessen J, Thijs L, Fagard R, Ulian L, Mancia G
Centro di Fisiologia Clinica e Ipertensione, Ospedale Maggiore and University of Milan, Italy.
J Hypertens. 1998 Jan;16(1):23-9. doi: 10.1097/00004872-199816010-00005.
The difference between clinic and ambulatory average daytime blood pressures is frequently taken as a surrogate measure of the 'white-coat effect' (i.e. the pressor reaction triggered in the patient by the physician's visit).
To assess the reproducibility of this difference and its relationship with clinic and average ambulatory daytime blood pressure levels.
These issues were addressed with two large groups of subjects in whom both clinic and ambulatory blood pressures were measured, namely 783 outpatients with systolic and diastolic essential hypertension [Group 1, aged 50.8+/-9.4 years (mean +/- SD)], participating in standardized Italian trials of antihypertensive drugs, and 506 elderly patients (group 2, age 71+/-7 years) with isolated systolic hypertension, participating in the European Syst-Eur trial.
The clinic-daytime blood pressure difference for the essential systolic and diastolic hypertensive patients (group 1) was 13.6+/-14.3 mmHg for systolic and 9.1+/-8.6 mmHg for diastolic blood pressure (P always < 0.01). This difference for the elderly patients with isolated systolic hypertension (group 2) was 21.2+/-16.0 mmHg for systolic and only 1.3+/-10.2 mmHg for diastolic blood pressure (P < 0.01 and P < 0.05, respectively). In both studies little or no systematic clinic-daytime difference could be observed for heart rate. The reproducibility of the clinic-daytime blood pressure difference, tested for 108 essential systolic and diastolic hypertensive patients from group 1 and 128 isolated systolic hypertensives from group 2, was invariably lower than that both of daytime and of clinic blood pressure values. Finally, the clinic-daytime blood pressure difference was progressively higher for increasing levels of clinic blood pressure and progressively lower for higher levels of ambulatory daytime blood pressure.
Thus, the clinic-daytime blood pressure difference has a limited reproducibility; depends not only on clinic but also on daytime average blood pressure, which means that its size is a function of the blood pressure criteria employed for selection of the patients in a trial; and is never associated with a systematic clinic-daytime difference in heart rate, which further questions its use as a reliable surrogate measure of the true pressor response induced in the patient by the doctor's visit.
临床血压与动态日间平均血压之间的差异常被用作“白大衣效应”（即医生问诊引发患者的升压反应）的替代指标。
评估这种差异的可重复性及其与临床血压和动态日间平均血压水平的关系。
在两组大规模受试者中研究这些问题，这两组受试者均测量了临床血压和动态血压，即783例收缩期和舒张期原发性高血压门诊患者[第1组，年龄50.8±9.4岁（均值±标准差）]，参与意大利标准化抗高血压药物试验，以及506例单纯收缩期高血压老年患者（第2组，年龄71±7岁），参与欧洲收缩期高血压治疗试验（Syst-Eur试验）。
原发性收缩期和舒张期高血压患者（第1组）的临床与日间血压差值，收缩压为13.6±14.3 mmHg，舒张压为9.1±8.6 mmHg（P均<0.01）。单纯收缩期高血压老年患者（第2组）的这一差值，收缩压为21.2±16.0 mmHg，舒张压仅为1.3±10.2 mmHg（分别为P<0.01和P<0.05）。在两项研究中，心率几乎未观察到或根本未观察到临床与日间的系统性差异。对第1组的108例原发性收缩期和舒张期高血压患者以及第2组的128例单纯收缩期高血压患者进行测试，结果表明临床与日间血压差值的可重复性始终低于日间血压值和临床血压值。最后，随着临床血压水平升高，临床与日间血压差值逐渐增大；随着动态日间血压水平升高，该差值逐渐减小。
因此，临床与日间血压差值的可重复性有限；不仅取决于临床血压，还取决于日间平均血压，这意味着其大小是试验中用于选择患者的血压标准的函数；并且与心率的临床与日间系统性差异无关，这进一步质疑了其作为医生问诊在患者中引发的真正升压反应的可靠替代指标的用途。
