Blood pressure lowering efficacy of beta-blockers as second-line therapy for primary hypertension
Editorial Group: Cochrane Hypertension Group
Published Online: 20 JAN 2010
Assessed as up-to-date: 10 NOV 2009
Copyright © 2010 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
How to Cite
Chen JMH, Heran BS, Perez MI, Wright JM. Blood pressure lowering efficacy of beta-blockers as second-line therapy for primary hypertension. Cochrane Database of Systematic Reviews 2010, Issue 1. Art. No.: CD007185. DOI: 10.1002/14651858.CD007185.pub2.
- Publication Status: New
- Published Online: 20 JAN 2010
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.
Data collection and analysis
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.
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.
Plain language summary
Beta-blockers lower blood pressure when given as a second drug
Beta-blockers are commonly used in the treatment for high blood pressure (BP). In this review, we asked how much do beta-blockers reduce BP when used as the second drug to treat hypertension. Twenty trials lasting an average of 7 weeks were found in the world scientific literature to answer this question. The data showed that the addition of a beta-blocker to thiazide diuretics or calcium channel blockers reduced BP by 8/6 mmHg when given at doses 2 times the recommended starting dose. When we compared these results with our previous review of the blood pressure lowering effect of thiazide diuretics as second line drug, we found that beta-blockers have a different pattern of BP lowering. This different pattern of effect on blood pressure might explain why first-line beta-blockers appear to be less effective at reducing adverse cardiovascular outcomes than first-line thiazide diuretics, particularly in older individuals.
量化乙型阻斷劑作為成年人本態性高血壓第二線治療的各種效果，包括收縮壓、 (SBP) 、舒張壓 (DBP) 、心律和因為治療產生的副作用而停藥的比例。
我們搜尋了CENTRAL (The Cochrane Library 2009, Issue 2), MEDLINE (1966Aug 2009), EMBASE (1988Aug 2009) 和bibliographic citations of articles and reviews。
總共有20個雙盲隨機對照試驗評估乙型阻斷劑作為成年人本態性高血壓第二線治療的降壓效果，共有3744位高血壓病患 (試驗開始前之平均血壓為150/102毫米汞柱，平均試驗時間為七週) 。評估加上乙型阻斷劑作為第二線治療的降壓效果的方式為比較使用乙型阻斷劑合併另一類藥物時和單獨使用此類藥物時血壓的差異。當thiazide類利尿劑或是鈣離子阻斷劑加上生產商建議的起始劑量的25% 乙型阻斷劑時就開始有血壓下降的效果。乙型阻斷劑作為第二線治療的降壓效果在建議的起始劑量的1倍時為6/4毫米汞柱，2倍時為8/6毫米汞柱。乙型阻斷劑在建議的起始劑量的1到2倍時減少心跳每分鐘10下。因為藥物不良反應而停用乙型阻斷劑在統計學上並無有意義的增加，但這可能是因為其中35% 的隨機對照試驗都沒有這方面的評估報告。
使用利尿劑或是鈣離子阻斷劑後再加上乙型阻斷劑，其降低血壓的效果在起始劑量的1倍時為6/4毫米汞柱，2倍時為8/6毫米汞柱。乙型阻斷劑作為第二線治療的降壓效果拿來跟我們之前對thiazide類利尿劑作為第二線治療的降壓效果所做的系統性回顧 (Chen 2009) 結果來做比較時，可以發現兩者對於收縮壓的下降程度是差不多的，但乙型阻斷劑可降低舒張壓的程度更多。這樣的差異代表乙型阻斷劑對於脈壓的影響是很少甚至是沒有的，而thiazide類利尿劑則可減少脈壓，且隨著劑量越大，減少的幅度越多。兩者降低血壓形式的不同可以解釋為何乙型阻斷劑對於減少不良心血管事件的效果較差，尤其是在年紀較大的族群。
此翻譯計畫由臺灣國家衛生研究院 (National Health Research Institutes, Taiwan) 統籌。