Chen Jenny Mh, Heran Balraj S, Perez Marco I, Wright James M
Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, Canada, V6T 1Z3.
Cochrane Database Syst Rev. 2010 Jan 20(1):CD007185. doi: 10.1002/14651858.CD007185.pub2.
Beta-blockers are one of the more commonly prescribed classes of anti-hypertensive drugs, both as first-line and second-line.
To quantify the effect on systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate and withdrawals due to adverse effects of beta-blocker therapy when given as a second-line drug in adult patients with primary hypertension.
CENTRAL (The Cochrane Library 2009, Issue 2), MEDLINE (1966-Aug 2009), EMBASE (1988-Aug 2009) and bibliographic citations of articles and reviews were searched.
Double-blind, randomized controlled trials comparing a beta-blocker in combination with a drug from another class of anti-hypertensive drugs compared with that drug alone for a duration of 3 to 12 weeks in patients with primary hypertension were included.
Two reviewers independently extracted the data and assessed trial quality of each included study.
20 double-blind RCTs evaluated the BP lowering efficacy of beta-blockers as second-line drug in 3744 hypertensive patients (baseline BP of 158/102 mmHg; mean duration of 7 weeks). The BP reduction from adding a beta-blocker as the second drug was estimated by comparing the difference in BP reduction between the combination and monotherapy groups. A reduction in BP was seen with adding a beta-blocker to thiazide diuretics or calcium channel blockers at doses as low as 0.25 times the manufacturer's recommended starting dose. The BP lowering efficacy of beta-blockers as a second drug was 6/4 mmHg at 1 times the starting dose and 8/6 mmHg at 2 times the starting dose. Beta-blockers reduced heart rate by 10 beats/min at 1 to 2 times the starting dose. Beta-blockers did not statistically significantly increase withdrawals due to adverse effects but this was likely due to the lack of reporting of this outcome in 35% of the included RCTs.
AUTHORS' CONCLUSIONS: Addition of a beta-blocker to diuretics or calcium-channel blockers reduces BP by 6/4mmHg at 1 times the starting dose and by 8/6 mmHg at 2 times the starting dose. When the blood pressure lowering effect of beta-blockers from this review was compared to that of thiazide diuretics from our previous review (Chen 2009), second-line beta-blockers reduce systolic BP to the same extent as second-line thiazide diuretics, but reduce diastolic BP to a greater degree. The different effect on diastolic BP means that beta-blockers have little or no effect on pulse pressure whereas thiazides cause a significant dose-related decrease in pulse pressure. This difference in the pattern of BP lowering with beta-blockers as compared to thiazides might be the explanation for the fact that beta-blockers appear to be less effective at reducing adverse cardiovascular outcomes than thiazide diuretics, particularly in older individuals.
β受体阻滞剂是较为常用的抗高血压药物类别之一，可作为一线和二线用药。
量化β受体阻滞剂作为二线药物用于成年原发性高血压患者时，对收缩压（SBP）、舒张压（DBP）、心率以及因不良反应导致停药情况的影响。
检索了Cochrane中心对照临床试验注册库（2009年第2期）、医学期刊数据库（1966年至2009年8月）、荷兰医学文摘数据库（1988年至2009年8月）以及文章和综述的参考文献。
纳入原发性高血压患者中，比较β受体阻滞剂与另一类抗高血压药物联合使用和单独使用该药物，为期3至12周的双盲随机对照试验。
两名评价员独立提取数据并评估每项纳入研究的试验质量。
20项双盲随机对照试验评估了β受体阻滞剂作为二线药物在3744例高血压患者（基线血压为158/102 mmHg；平均疗程7周）中的降压疗效。通过比较联合治疗组和单药治疗组血压降低的差异，估算添加β受体阻滞剂作为第二种药物后的血压降低情况。在噻嗪类利尿剂或钙通道阻滞剂中添加β受体阻滞剂，剂量低至制造商推荐起始剂量的0.25倍时，血压即可降低。β受体阻滞剂作为第二种药物，起始剂量1倍时降压疗效为6/4 mmHg，2倍时为8/6 mmHg。起始剂量1至2倍时，β受体阻滞剂可使心率降低10次/分钟。β受体阻滞剂未使因不良反应导致的停药率有统计学意义的显著增加，但这可能是由于35%的纳入随机对照试验未报告该结果。
在利尿剂或钙通道阻滞剂中添加β受体阻滞剂，起始剂量1倍时血压降低6/4 mmHg，2倍时降低8/6 mmHg。将本综述中β受体阻滞剂的降压效果与我们之前综述（Chen 2009）中噻嗪类利尿剂的效果进行比较时发现，二线β受体阻滞剂降低收缩压的程度与二线噻嗪类利尿剂相同，但降低舒张压的程度更大。对舒张压的不同影响意味着β受体阻滞剂对脉压影响很小或无影响，而噻嗪类药物会使脉压出现显著的剂量相关下降。与噻嗪类药物相比，β受体阻滞剂降压模式的这种差异可能解释了β受体阻滞剂在降低不良心血管结局方面似乎不如噻嗪类利尿剂有效的原因，尤其是在老年个体中。
