Felmeden D C, Lip G Y, Beevers M, Beevers D G
University Department of Medicine, City Hospital, Birmingham, UK.
Blood Press. 2000;9(6):335-9. doi: 10.1080/080370500300000914.
It is well recognised from many clinical trials that there is a blood pressure lowering effect when placebo is administered to patients with essential hypertension ("placebo effect"). The reduction in blood pressure, however, may also be partly due to loss of the alerting response ("white coat effect") as a result of familiarisation with the clinical environment. To investigate the hypothesis that there may be a more marked placebo effect and white coat effect in isolated systolic hypertension (ISH) compared with systo-diastolic hypertension (SDH), we studied 78 patients with hypertension: 34 had ISH and 44 patients had SDH. The 34 patients with ISH were older (68.7 vs 54.9 years), had a higher SBP (192.2 vs 169.6 mmHfg) and lower DBP (85.5 vs 102.0 mmHg) when compared to patients with SDH. Amongst the patients with ISH, there were no significant changes in mean blood pressures pre-placebo (paired t-test, p = NS). In the placebo period, there was a significant reduction in systolic blood pressures at all three points, and a significant reduction in diastolic blood pressures after 2 and 3 months placebo (paired t-test, p < 0.05). There was a mean reduction in mean systolic blood pressure at visit 1 by 5.2%, visit 2 by 5.1% and visit 3 by 4.6%, when compared to mean pre-placebo systolic blood pressures (p < 0.05). The mean reduction in diastolic blood pressure was 5.8% at visit 2 and 3.5% at visit 3, when compared to mean pre-placebo diastolic blood pressure (p < 0.05). At the 4-week visit after receiving placebo, the mean systolic blood pressure decreased by 9.4 mmHg (p = 0.003) and mean diastolic blood pressure by 2.7 mmHg (p = NS) in the patients with ISH. In patients with SDH, there were no statistically significant changes in recorded BP readings following the introduction of placebo. We suggest blood pressures in some patients with ISH may settle with careful follow up and initiation of treatment in these patients could potentially be delayed for at least 3 months, as therapy may not prove necessary.
许多临床试验已充分认识到，给原发性高血压患者服用安慰剂时会有降压效果（“安慰剂效应”）。然而，血压降低也可能部分归因于因熟悉临床环境而失去警觉反应（“白大衣效应”）。为了研究与收缩期-舒张期高血压（SDH）相比，单纯收缩期高血压（ISH）可能存在更显著的安慰剂效应和白大衣效应这一假设，我们对78例高血压患者进行了研究：34例为ISH患者，44例为SDH患者。与SDH患者相比，34例ISH患者年龄更大（68.7岁对54.9岁），收缩压更高（192.2 mmHg对169.6 mmHg），舒张压更低（85.5 mmHg对102.0 mmHg）。在ISH患者中，服用安慰剂前平均血压无显著变化（配对t检验，p =无统计学意义）。在安慰剂期，所有三个时间点的收缩压均显著降低，服用安慰剂2个月和3个月后舒张压显著降低（配对t检验，p < 0.05）。与服用安慰剂前的平均收缩压相比，第1次就诊时平均收缩压平均降低5.2%，第2次就诊时降低5.1%，第3次就诊时降低4.6%（p < 0.05）。与服用安慰剂前的平均舒张压相比，第2次就诊时舒张压平均降低5.8%，第3次就诊时降低3.5%（p < 0.05）。在ISH患者中，服用安慰剂4周后就诊时，平均收缩压降低9.4 mmHg（p = 0.003），平均舒张压降低2.7 mmHg（p =无统计学意义）。在SDH患者中，服用安慰剂后记录的血压读数无统计学显著变化。我们建议，一些ISH患者的血压可能通过仔细随访而稳定下来，这些患者的治疗启动可能潜在地延迟至少3个月，因为可能无需治疗。
