Reeves R A, Myers M G
Department of Medicine, Sunnybrook Health Science Center, University of Toronto, Ontario, Canada.
Am J Hypertens. 1993 Jun;6(6 Pt 2):229S-232S.
Ambulatory blood pressure monitoring (ABPM), like casual blood pressure (BP), is imperfectly reproducible between visits. The reproducibility of ABPM is less than the reproducibility predicted from a simple model of random variation of BP. This suggests either increased technical error in the technique, an element of increased biologic variability, or both. In addition, ABP shows a between-day variation (add about 6 to 7 mm Hg diastolic, similar in magnitude to what is observed with casual BP) which cannot be obviated by the average of many within-day measurements. The reliability of ABPM, although conventionally judged excellent at about RI = 0.75, is insufficient to avoid misclassification errors and regression to the mean when BP cutpoints are employed. About 40% of patients apparently failing treatment withdrawal at a threshold of +2 SD, or about 95 mm Hg diastolic ABP, will be false-positive failures when categorized by a single ABP. Despite the inconvenience, obtaining an average of two or more ABP measurements on different days may be cost-saving to a clinical trial because of the improved reproducibility; other costs may exceed $1000 per entrant.
动态血压监测（ABPM）与偶测血压（BP）一样，不同次就诊间的重复性欠佳。ABPM的重复性低于根据血压随机变化的简单模型所预测的重复性。这表明要么该技术存在更多技术误差，要么存在更大的生物变异性因素，或者两者皆有。此外，ABP还表现出日间变化（舒张压增加约6至7毫米汞柱，幅度与偶测血压所见相似），多次日内测量的平均值无法消除这种变化。尽管传统上认为ABPM的可靠性在约RI = 0.75时非常好，但当采用血压切点时，其可靠性不足以避免误分类错误和向均值回归。当以单个ABP进行分类时，约40%在+2标准差（即舒张期ABP约95毫米汞柱）阈值下看似治疗撤药失败的患者将为假阳性失败。尽管不便，但在不同日期平均进行两次或更多次ABP测量可能因重复性提高而为临床试验节省成本；其他成本可能超过每位参与者1000美元。
