Mancia G, Omboni S, Parati G, Ravogli A, Villani A, Zanchetti A
Cattedra di Medicina Interna and Clinica Medica, Università di Milano, Italy.
Am J Hypertens. 1995 Mar;8(3):311-5. doi: 10.1016/0895-7061(94)00250-F.
Several studies have reported that, at variance with clinic blood pressure, ambulatory blood pressure is not reduced by treatment with placebo. However, this evidence has usually been obtained in small groups of subjects and no data are available from a larger sample of patients. To address this issue we have analyzed data from 116 outpatients involved in placebo-controlled studies on antihypertensive treatment. The patients were studied before and at the end of a 6- to 8-week period of placebo. In all patients, blood pressure was measured by sphygmomanometry and over the 24 h by automatic ambulatory monitoring. Administration of placebo was accompanied by a significant reduction in systolic and diastolic clinic blood pressure (-5.3 +/- 1.1 and -4.4 +/- 0.6 mm Hg, respectively; P < .01), but not in 24-h, daytime and nighttime blood pressure. Hourly systolic and diastolic blood pressure profiles were virtually superimposable in the two different periods, except for the first 4 h, in which systolic blood pressure was slightly but significantly lower during than before placebo (149.5 +/- 1.2 v 146.4 +/- 1.2 mm Hg; P < .05). These results provide a large database indicating that 24-h average blood pressure is not reduced by placebo, thus it is not necessary to include a placebo control group in antihypertensive drug studies in which ambulatory blood pressure monitoring is employed. A small placebo effect occurs, however, in the first hours of ambulatory monitoring. This may lead to a slight overestimation of the peak blood pressure effect of a drug and an underestimation of its trough-to-peak ratio if placebo correction of the data is not made or if the first part of ambulatory blood pressure monitoring is not excluded from data analysis.
多项研究报告称，与诊室血压不同，动态血压并不会因安慰剂治疗而降低。然而，这一证据通常是在少数受试者中获得的，尚无来自更大患者样本的数据。为解决这一问题，我们分析了参与抗高血压治疗安慰剂对照研究的116名门诊患者的数据。在为期6至8周的安慰剂治疗期开始前和结束时对患者进行了研究。所有患者均通过血压计测量血压，并通过自动动态监测仪进行24小时监测。服用安慰剂后，诊室收缩压和舒张压显著降低（分别为-5.3±1.1和-4.4±0.6 mmHg；P<.01），但24小时、日间和夜间血压并未降低。除前4小时外，两个不同时期的每小时收缩压和舒张压曲线几乎重叠，在前4小时内，收缩压在服用安慰剂期间略低于服用前，但差异显著（149.5±1.2对146.4±1.2 mmHg；P<.05）。这些结果提供了一个大型数据库，表明安慰剂不会降低24小时平均血压，因此在采用动态血压监测的抗高血压药物研究中，无需设立安慰剂对照组。然而，在动态监测的最初几个小时会出现较小的安慰剂效应。如果不对数据进行安慰剂校正，或者不将动态血压监测的第一部分排除在数据分析之外，这可能会导致对药物峰值血压效应的轻微高估以及对其谷峰比的低估。
