Parati G, Omboni S, Mancia G
Istituto Scientifico Ospedale S. Luca, Centro Auxologico Italiano, Milano, Italy.
J Hypertens. 1996 Jun;14(6):791-7. doi: 10.1097/00004872-199606000-00016.
To investigate whether a clinic-ambulatory blood pressure difference persists with time under active drug treatment or placebo and to determine whether and how it interferes with the evaluation of the efficacy of antihypertensive treatment.
In 382 mild or moderate essential hypertensive patients (mean age +/- SD 51.5 +/- 9.2 years) clinic and ambulatory (SpaceLabs 90207 device) blood pressures were measured twice, under baseline conditions and after 4-8 weeks of antihypertensive treatment by calcium antagonists or angiotensin converting enzyme inhibitors (n = 266) or of placebo administration (n = 116). In each patient the difference between clinic and daytime average blood pressure was taken as a surrogate measure of the magnitude of the 'white-coat effect', separately for systolic and diastolic blood pressures. The changes in this difference induced by treatment and by placebo and the relationship between the blood pressure changes induced by drug treatment and by placebo and the magnitude of the difference before and during treatment or placebo, respectively, were computed.
Before drug treatment, the difference was 16.6 +/- 13.6 and 10.1 +/- 7.9 mmHg for systolic and diastolic blood pressures, respectively. During treatment the corresponding values were 11.9 +/- 14.2 and 6.8 +/- 9.2 mmHg; both of the reductions were statistically significant. Both for systolic and for diastolic blood pressure, the reduction in clinic blood pressure caused by treatment was directly related to the clinic-ambulatory difference before treatment, but inversely related to the magnitude of that difference persisting during treatment. The clinic-ambulatory blood pressure difference observed before placebo was attenuated during placebo, the magnitude of the attenuation being similar to that found under drug treatment. No significant difference between clinic and daytime average heart rate was ever observed before and during active treatment or placebo.
A considerable clinic-ambulatory blood pressure difference persists during several weeks of antihypertensive treatment, but its magnitude is significantly attenuated. This leads to an overestimation of the effectiveness of antihypertensive treatment when this is assessed by clinic blood pressure measurements only. This overestimation is greater in subjects with an initially greater difference because in these subjects the subsequent attenuation is greater. Because similar phenomena are observed with placebo, the attenuation in the difference during drug treatment is likely to reflect merely habituation to clinic blood pressure measurements with time.
研究在积极药物治疗或安慰剂治疗下，诊室血压与动态血压差值是否会随时间持续存在，并确定其是否以及如何干扰抗高血压治疗疗效的评估。
对382例轻度或中度原发性高血压患者（平均年龄±标准差51.5±9.2岁），在基线条件下以及使用钙拮抗剂或血管紧张素转换酶抑制剂进行抗高血压治疗4 - 8周后（n = 266）或给予安慰剂后（n = 116），使用SpaceLabs 90207设备测量两次诊室血压和动态血压。在每位患者中，将诊室血压与日间平均血压的差值作为“白大衣效应”大小的替代指标，分别针对收缩压和舒张压进行测量。计算治疗和安慰剂引起的该差值变化，以及药物治疗和安慰剂引起的血压变化与治疗或安慰剂之前及期间差值大小之间的关系。
在药物治疗前，收缩压和舒张压的差值分别为16.6±13.6 mmHg和10.1±7.9 mmHg。治疗期间相应的值分别为11.9±14.2 mmHg和6.8±9.2 mmHg；两者的降低均具有统计学意义。对于收缩压和舒张压，治疗引起的诊室血压降低与治疗前的诊室 - 动态血压差值直接相关，但与治疗期间持续存在的该差值大小呈负相关。在安慰剂治疗前观察到的诊室 - 动态血压差值在安慰剂治疗期间减弱，减弱幅度与药物治疗下观察到的相似。在积极治疗或安慰剂治疗之前及期间，未观察到诊室心率与日间平均心率之间存在显著差异。
在数周的抗高血压治疗期间，诊室血压与动态血压之间存在相当大的差值，但差值大小显著减弱。仅通过诊室血压测量评估抗高血压治疗效果时，这会导致对治疗效果的高估。在初始差值较大的受试者中，这种高估更为明显，因为在这些受试者中，随后的减弱更为显著。由于在安慰剂治疗中也观察到类似现象，药物治疗期间差值的减弱可能仅仅反映了随着时间推移对诊室血压测量的习惯化。
