First-line drugs for hypertension

Calcium channel blockers versus other classes of drugs for hypertension

BACKGROUND

Calcium channel blockers (CCBs) are a relatively new antihypertensive class. The effect of first-line CCBs on the prevention of cardiovascular events, as compared with other antihypertensive drug classes, is unknown.

OBJECTIVES

To determine whether CCBs used as first-line therapy for hypertension are different from other first-line drug classes in reducing the incidence of major adverse cardiovascular events.

SEARCH STRATEGY

Electronic searches of the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASEand the WHO-ISH Collaboration Register (up to May 2009) were performed. We also checked the references of published studies to identify additional trials.

SELECTION CRITERIA

Randomized controlled trial (RCT) comparing first-line CCBs with other antihypertensive classes, with at least 100 randomized hypertensive participants and with a follow-up of at least two years.

DATA COLLECTION AND ANALYSIS

Two authors independently selected the included trials, evaluated the risk of bias and entered the data for analysis.

MAIN RESULTS

Eighteen RCTs (14 dihydropyridines, 4 non-dihydropyridines) with a total of 141,807 participants were included. All-cause mortality was not different between first-line CCBs and any other first-line antihypertensive classes. CCBs reduced the following outcomes as compared to beta-blockers: total cardiovascular events (RR 0.84, 95% CI [0.77, 0.92]), stroke (RR 0.77, 95% CI [0.67, 0.88]) and cardiovascular mortality (RR 0.90, 95% CI [0.81, 0.99]). CCBs increased total cardiovascular events (RR 1.05 , 95% CI [1.00, 1.09], p = 0.03) and congestive heart failure events (RR 1.37, 95% CI [1.25, 1.51]) as compared to diuretics. CCBs reduced stroke (RR 0.89, 95% CI [0.80, 0.98]) as compared to ACE inhibitors and reduced stroke (RR 0.85, 95% CI [0.73, 0.99]) and MI (RR 0.83, 95% CI [0.72, 0.96]) as compared to ARBs. CCBs also increased congestive heart failure events as compared to ACE inhibitors (RR 1.16, 95% CI [1.06, 1.27]) and ARBs (RR 1.20, 95% CI [1.06, 1.36]). The other evaluated outcomes were not significantly different.

AUTHORS' CONCLUSIONS

Diuretics are preferred first-line over CCBs to optimize reduction of cardiovascular events. The review does not distinguish between CCBs, ACE inhibitors or ARBs, but does provide evidence supporting the use of CCBs over beta-blockers. Many of the differences found in the current review are not robust and further trials might change the conclusions. More well-designed RCTs studying the mortality and morbidity of patients taking CCBs as compared with other antihypertensive drug classes are needed for patients with different stages of hypertension, different ages, and with different co-morbidities such as diabetes.

Pharmaceutical policies: effects of restrictions on reimbursement

BACKGROUND

Public policy makers and benefit plan managers need to restrain rising pharmaceutical drug costs while preserving access and optimizing health benefits.

OBJECTIVES

To determine the effects of a pharmaceutical policy restricting the reimbursement of selected medications on drug use, health care utilization, health outcomes and costs (expenditures).

SEARCH STRATEGY

We searched the 14 major bibliographic databases and websites (to January 2009).

SELECTION CRITERIA

Included were studies of pharmaceutical policies that restrict coverage and reimbursement of selected drugs or drug classes, often using additional patient specific information related to health status or need. We included randomised controlled trials, non-randomised controlled trials, interrupted time series (ITS) analyses, repeated measures studies and controlled before-after studies set in large care systems or jurisdictions.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed study limitations. Quantitative re-analysis of time series data was undertaken for studies with sufficient data.

MAIN RESULTS

We included 29 ITS analyses (12 were controlled) investigating policies targeting 11 drug classes for restriction. Participants were most often senior citizens or low income adult populations, or both, in publically subsidized or administered pharmaceutical benefit plans. Impact of policies varied by drug class and whether restrictions were implemented or relaxed. When policies targeted gastric-acid suppressant and non-steroidal anti-inflammatory drug classes, decreased drug use and substantial savings on drugs occurred immediately and for up to two years afterwards, with no increase in the use of other health services (6 studies). Targeting second generation antipsychotic drugs increased treatment discontinuity and the use of other health services without reducing overall drug expenditures (2 studies). Relaxing restrictions for reimbursement of antihypertensives and statins increased appropriate use and decreased overall drug expenditures. Two studies which measured health outcomes directly were inconclusive.

AUTHORS' CONCLUSIONS

Implementing restrictions to coverage and reimbursement of selected medications can decrease third-party drug spending without increasing the use of other health services (6 studies). Relaxing reimbursement rules for drugs used for secondary prevention can also remove barriers to access. Policy design, however, needs to be based on research quantifying the harm and benefit profiles of target and alternative drugs to avoid unwanted health system and health effects. Health impact evaluation should be conducted where drugs are not interchangeable. Impacts on health equity, relating to the fair and just distribution of health benefits in society (sustainable access to publically financed drug benefits for seniors and low income populations, for example), also require explicit measurement.

Blood pressure lowering efficacy of beta-blockers as second-line therapy for primary hypertension

BACKGROUND

Beta-blockers are one of the more commonly prescribed classes of anti-hypertensive drugs, both as first-line and second-line.

OBJECTIVES

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.

SEARCH STRATEGY

CENTRAL (The Cochrane Library 2009, Issue 2), MEDLINE (1966-Aug 2009), EMBASE (1988-Aug 2009) and bibliographic citations of articles and reviews were searched.

SELECTION CRITERIA

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.

MAIN RESULTS

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.

Cardiovascular risk management and its impact on hypertension control in primary care in low-resource settings: a cluster-randomized trial

OBJECTIVE

To evaluate a simple cardiovascular risk management package for assessing and managing cardiovascular risk using hypertension as an entry point in primary care facilities in low-resource settings.

METHODS

Two geographically distant regions in two countries (China and Nigeria) were selected and 10 pairs of primary care facilities in each region were randomly selected and matched. Regions were then randomly assigned to a control group, which received usual care, or to an intervention group, which applied the cardiovascular risk management package. Each facility enrolled 60 consecutive patients with hypertension. Intervention sites educated patients about risk factors at baseline and initiated treatment with hydrochlorothiazide at 4 months in patients at medium risk of a cardiovascular event, according to a standardized treatment algorithm. Systolic blood pressure change from baseline to 12 months was the primary outcome measure.

FINDINGS

The study included 2397 patients with baseline hypertension: 1191 in 20 intervention facilities and 1206 in 20 control facilities. Systolic and diastolic blood pressure decreased more in intervention patients than in controls. However, at 12 months more than half of patients still had uncontrolled hypertension (systolic blood pressure > 140 mmHg and/or diastolic blood pressure > 90 mmHg). Behavioural risk factors had improved among intervention patients in Nigeria but not in China. Only about 2% of hypertensive patients required referral to the next level of care.

CONCLUSION

Even in low-resource settings, hypertensive patients can be effectively assessed and managed in primary care facilities.

Blood pressure lowering efficacy of loop diuretics for primary hypertension

BACKGROUND

Antihypertensive drugs from the thiazide diuretic drug class have been shown to reduce mortality and cardiovascular morbidity. Loop diuretics are indicated and used as antihypertensive drugs but a systematic review of their blood pressure lowering efficacy or effectiveness in terms of reducing cardiovascular mortality or morbidity from randomized controlled trial evidence has not been conducted.

OBJECTIVES

To determine the dose related decrease in systolic and/or diastolic blood pressure as well as adverse events leading to patient withdrawal and adverse biochemical effects (serum potassium, uric acid, creatinine, glucose and lipids profile) due to loop diuretics versus placebo control in the treatment of patients with primary hypertension.

SEARCH STRATEGY

Medline (Jan.1966-March-2009), EMBASE (Jan.1988-March-2009), CENTRAL (issue 1, 2009) and bibliographic citations were searched.

SELECTION CRITERIA

Double blind randomized placebo controlled trials of at least 3 weeks duration comparing loop diuretic with a placebo or no treatment in patients with primary hypertension defined as BP >140/90 mmHg at baseline were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Weighted mean difference and a fixed effects model were used to combine continuous outcome data. The drop outs due to adverse effects was analysed using relative risk ratio.

MAIN RESULTS

Nine trials evaluated the dose-related blood pressure lowering efficacy of five drugs within the loop diuretics class (furosemide 40 to 60mg, cicletanine 100 to 150 mg, piretanide 3 to 6 mg, indacrinone enantiomer -2.5 to -10.0/+80 mg and etozolin 200 mg) in 460 patients with baseline blood pressure of 162/103 mmHg for a mean duration of 8.8 weeks. The best estimate of SBP/DBP lowering efficacy of loop diuretics was -7.9 (-10.5, -5.4) mmHg/ -4.4 (-5.6, -2.8) mmHg . Withdrawals due to adverse effects and serum biochemical changes did not show a significant difference.

AUTHORS' CONCLUSIONS

Based on the limited number of published RCTs, the SBP/DBP lowering effect of loop diuretics is modest -8/-4 mmHg and is likely an overestimate due to the high risk of bias in the included studies. There is no clinically meaningful BP lowering differences between different drugs within the loop diuretic class. The dose ranging effects of loop diuretics could not be evaluated.The review did not provide a good estimate of the incidence of harms associated because of the short duration of the trials and the lack of reporting of adverse effects in many of the trials.

Blood pressure lowering efficacy of diuretics as second-line therapy for primary hypertension

BACKGROUND

Diuretics are widely prescribed for hypertension not only as a first-line drug but also as a second-line drug. Therefore, it is essential to determine the effects of diuretics on blood pressure (BP), heart rate and withdrawals due to adverse effects (WDAEs) when given as a second-line drug.

OBJECTIVES

To quantify the additional reduction in systolic blood pressure (SBP) and diastolic blood pressure (DBP) of diuretic therapy as a second-line drug in patients with primary hypertension

SEARCH STRATEGY

CENTRAL (The Cochrane Library 2008, Issue 2), MEDLINE (1966-July 2008), EMBASE (1988-July 2008) and bibliographic citations of articles and reviews were searched.

SELECTION CRITERIA

Double-blind, randomized, controlled trials evaluating the BP lowering efficacy of a diuretic in combination therapy with another class of anti-hypertensive drugs compared with the respective monotherapy (without a diuretic) for a duration of 3 to 12 weeks in patients with primary hypertension.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data and assessed trial quality.

MAIN RESULTS

Fifty-three double-blind RCTs evaluating a thiazide in 15129 hypertensive patients (baseline BP of 156/101 mmHg) were included. Hydrochlorothiazide was the thiazide used in 49/53 (92%) of the included studies. The additional BP reduction caused by the thiazide as a second drug was estimated by comparing the difference in BP reduction between the combination and monotherapy groups. Thiazides as a second-line drug reduced BP by 6/3 and 8/4 mmHg at doses of 1 and 2 times the manufacturer's recommended starting dose respectively. The BP lowering effect was dose related. The effect was similar to that obtained when thiazides are used as a single agent. Only 3 double-blind RCTs evaluating loop diuretics were identified. These RCTs showed a BP lowering effect of a starting dose of about 6/3 mmHg.

AUTHORS' CONCLUSIONS

Thiazides when given as a second-line drug have a dose related effect to lower blood pressure that is similar to when they are added as a first-line drug. This means that the BP lowering effect of thiazides is additive. Loop diuretics appear to have a similar blood pressure lowering effect as thiazides at 1 times the recommended starting dose. Because of the short duration of the trials and lack of reporting of adverse events, this review does not provide a good estimate of the incidence of adverse effects of diuretics given as a second-line drug.

Factors affecting blood pressure variability: lessons learned from two systematic reviews of randomized controlled trials

Systematic reviews can often reveal much more than the original objective of the work. The objectives of this retrospective analysis were to answer three basic questions about blood pressure variability: 1) Does blood pressure entry criterion have an effect on baseline blood pressure variability? 2) Do thiazide diuretics have a significant effect on blood pressure variability? and 3) Does systolic blood pressure vary to the same degree as diastolic blood pressure? This analysis of blood pressure variability is based on resting standardized research setting BP readings from two systematic reviews evaluating blood pressure lowering efficacy of thiazide diuretics from double blind randomized controlled trials in 33,611 patients with primary hypertension. The standard deviation reported in trials was the focus of the research and the unit of analysis. When a threshold systolic or diastolic blood pressure value is used to determine entry into a trial, baseline variability is significantly decreased, systolic from 14.0 to 9.3 mmHg and diastolic from 8.4 to 5.3 mmHg. Thiazides do not change BP variability as the standard deviation and coefficient of variation of systolic blood pressure and diastolic blood pressure did not differ between thiazide and placebo groups at end of treatment. The coefficient of variation of systolic blood pressure was significantly greater than the coefficient of variation of diastolic blood pressure. Entry criterion decreases the baseline blood pressure variability. Treatment with a thiazide diuretic does not affect blood pressure variability. Systolic blood pressure varies to a greater degree than diastolic blood pressure.