Rationale and design for the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) Trial

Evening versus morning dosing regimen drug therapy for hypertension

BACKGROUND

Variation in blood pressure levels display circadian rhythms. Complete 24-hour blood pressure control is the primary goal of antihypertensive treatment and reducing adverse cardiovascular outcomes is the ultimate aim. This is an update of the review first published in 2011.

OBJECTIVES

To evaluate the effectiveness of administration-time-related effects of once-daily evening versus conventional morning dosing antihypertensive drug therapy regimens on all-cause mortality, cardiovascular mortality and morbidity, total adverse events, withdrawals from treatment due to adverse effects, and reduction of systolic and diastolic blood pressure in people with primary hypertension.

SEARCH METHODS

We searched the Cochrane Hypertension Specialised Register via Cochrane Register of Studies (17 June 2022), Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 6, 2022); MEDLINE, MEDLINE In-Process and MEDLINE Epub Ahead of Print (1 June 2022); Embase (1 June 2022); ClinicalTrials.gov (2 June 2022); Chinese Biomedical Literature Database (CBLD) (1978 to 2009); Chinese VIP (2009 to 7 August 2022); Chinese WANFANG DATA (2009 to 4 August 2022); China Academic Journal Network Publishing Database (CAJD) (2009 to 6 August 2022); Epistemonikos (3 September 2022) and the reference lists of relevant articles. We applied no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing the administration-time-related effects of evening with morning dosing monotherapy regimens in people with primary hypertension. We excluded people with known secondary hypertension, shift workers or people with white coat hypertension.

DATA COLLECTION AND ANALYSIS

Two to four review authors independently extracted data and assessed trial quality. We resolved disagreements by discussion or with another review author. We performed data synthesis and analyses using Review Manager Web for all-cause mortality, cardiovascular mortality and morbidity, serious adverse events, overall adverse events, withdrawals due to adverse events, change in 24-hour blood pressure and change in morning blood pressure. We assessed the certainty of the evidence using GRADE. We conducted random-effects meta-analysis, fixed-effect meta-analysis, subgroup analysis and sensitivity analysis.

MAIN RESULTS

We included 27 RCTs in this updated review, of which two RCTs were excluded from the meta-analyses for lack of data and number of groups not reported. The quantitative analysis included 25 RCTs with 3016 participants with primary hypertension. RCTs used angiotensin-converting enzyme inhibitors (six trials), calcium channel blockers (nine trials), angiotensin II receptor blockers (seven trials), diuretics (two trials), α-blockers (one trial), and β-blockers (one trial). Fifteen trials were parallel designed, and 10 trials were cross-over designed. Most participants were white, and only two RCTs were conducted in Asia (China) and one in Africa (South Africa). All trials excluded people with risk factors of myocardial infarction and strokes. Most trials had high risk or unclear risk of bias in at least two of several key criteria, which was most prominent in allocation concealment (selection bias) and selective reporting (reporting bias). Meta-analysis showed significant heterogeneity across trials. No RCTs reported on cardiovascular mortality and cardiovascular morbidity. There may be little to no differences in all-cause mortality (after 26 weeks of active treatment: RR 0.49, 95% CI 0.04 to 5.42; RD 0, 95% CI -0.01 to 0.01; very low-certainty evidence), serious adverse events (after 8 to 26 weeks of active treatment: RR 1.17, 95% CI 0.53 to 2.57; RD 0, 95% CI -0.02 to 0.03; very low-certainty evidence), overall adverse events (after 6 to 26 weeks of active treatment: RR 0.89, 95% CI 0.67 to 1.20; I² = 37%; RD -0.02, 95% CI -0.07 to 0.02; I² = 38%; very low-certainty evidence) and withdrawals due to adverse events (after 6 to 26 weeks active treatment: RR 0.76, 95% CI 0.47 to 1.23; I² = 0%; RD -0.01, 95% CI -0.03 to 0; I² = 0%; very low-certainty evidence), but the evidence was very uncertain.

AUTHORS' CONCLUSIONS

Due to the very limited data and the defects of the trials' designs, this systematic review did not find adequate evidence to determine which time dosing drug therapy regimen has more beneficial effects on cardiovascular outcomes or adverse events. We have very little confidence in the evidence showing that evening dosing of antihypertensive drugs is no more or less effective than morning administration to lower 24-hour blood pressure. The conclusions should not be assumed to apply to people receiving multiple antihypertensive drug regimens.

First-line diuretics versus other classes of antihypertensive drugs for hypertension

BACKGROUND

Different first-line drug classes for patients with hypertension are often assumed to have similar effectiveness with respect to reducing mortality and morbidity outcomes, and lowering blood pressure. First-line low-dose thiazide diuretics have been previously shown to have the best mortality and morbidity evidence when compared with placebo or no treatment. Head-to-head comparisons of thiazides with other blood pressure-lowering drug classes would demonstrate whether there are important differences.

OBJECTIVES

To compare the effects of first-line diuretic drugs with other individual first-line classes of antihypertensive drugs on mortality, morbidity, and withdrawals due to adverse effects in patients with hypertension. Secondary objectives included assessments of the need for added drugs, drug switching, and blood pressure-lowering.

SEARCH METHODS

Cochrane Hypertension's Information Specialist searched the Cochrane Hypertension Specialized Register, CENTRAL, MEDLINE, Embase, and trials registers to March 2021. We also checked references and contacted study authors to identify additional studies. A top-up search of the Specialized Register was carried out in June 2022.

SELECTION CRITERIA

Randomized active comparator trials of at least one year's duration were included. Trials had a clearly defined intervention arm of a first-line diuretic (thiazide, thiazide-like, or loop diuretic) compared to another first-line drug class: beta-blockers, calcium channel blockers, alpha adrenergic blockers, angiotensin converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, direct renin inhibitors, or other antihypertensive drug classes. Studies had to include clearly defined mortality and morbidity outcomes (serious adverse events, total cardiovascular events, stroke, coronary heart disease (CHD), congestive heart failure, and withdrawals due to adverse effects).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodological procedures.

MAIN RESULTS

We included 20 trials with 26 comparator arms randomizing over 90,000 participants. The findings are relevant to first-line use of drug classes in older male and female hypertensive patients (aged 50 to 75) with multiple co-morbidities, including type 2 diabetes. First-line thiazide and thiazide-like diuretics were compared with beta-blockers (six trials), calcium channel blockers (eight trials), ACE inhibitors (five trials), and alpha-adrenergic blockers (three trials); other comparators included angiotensin II receptor blockers, aliskiren (a direct renin inhibitor), and clonidine (a centrally acting drug). Only three studies reported data for total serious adverse events: two studies compared diuretics with calcium channel blockers and one with a direct renin inhibitor. Compared to first-line beta-blockers, first-line thiazides probably result in little to no difference in total mortality (risk ratio (RR) 0.96, 95% confidence interval (CI) 0.84 to 1.10; 5 trials, 18,241 participants; moderate-certainty), probably reduce total cardiovascular events (5.4% versus 4.8%; RR 0.88, 95% CI 0.78 to 1.00; 4 trials, 18,135 participants; absolute risk reduction (ARR) 0.6%, moderate-certainty), may result in little to no difference in stroke (RR 0.85, 95% CI 0.66 to 1.09; 4 trials, 18,135 participants; low-certainty), CHD (RR 0.91, 95% CI 0.78 to 1.07; 4 trials, 18,135 participants; low-certainty), or heart failure (RR 0.69, 95% CI 0.40 to 1.19; 1 trial, 6569 participants; low-certainty), and probably reduce withdrawals due to adverse effects (10.1% versus 7.9%; RR 0.78, 95% CI 0.71 to 0.85; 5 trials, 18,501 participants; ARR 2.2%; moderate-certainty). Compared to first-line calcium channel blockers, first-line thiazides probably result in little to no difference in total mortality (RR 1.02, 95% CI 0.96 to 1.08; 7 trials, 35,417 participants; moderate-certainty), may result in little to no difference in serious adverse events (RR 1.09, 95% CI 0.97 to 1.24; 2 trials, 7204 participants; low-certainty), probably reduce total cardiovascular events (14.3% versus 13.3%; RR 0.93, 95% CI 0.89 to 0.98; 6 trials, 35,217 participants; ARR 1.0%; moderate-certainty), probably result in little to no difference in stroke (RR 1.06, 95% CI 0.95 to 1.18; 6 trials, 35,217 participants; moderate-certainty) or CHD (RR 1.00, 95% CI 0.93 to 1.08; 6 trials, 35,217 participants; moderate-certainty), probably reduce heart failure (4.4% versus 3.2%; RR 0.74, 95% CI 0.66 to 0.82; 6 trials, 35,217 participants; ARR 1.2%; moderate-certainty), and may reduce withdrawals due to adverse effects (7.6% versus 6.2%; RR 0.81, 95% CI 0.75 to 0.88; 7 trials, 33,908 participants; ARR 1.4%; low-certainty). Compared to first-line ACE inhibitors, first-line thiazides probably result in little to no difference in total mortality (RR 1.00, 95% CI 0.95 to 1.07; 3 trials, 30,961 participants; moderate-certainty), may result in little to no difference in total cardiovascular events (RR 0.97, 95% CI 0.92 to 1.02; 3 trials, 30,900 participants; low-certainty), probably reduce stroke slightly (4.7% versus 4.1%; RR 0.89, 95% CI 0.80 to 0.99; 3 trials, 30,900 participants; ARR 0.6%; moderate-certainty), probably result in little to no difference in CHD (RR 1.03, 95% CI 0.96 to 1.12; 3 trials, 30,900 participants; moderate-certainty) or heart failure (RR 0.94, 95% CI 0.84 to 1.04; 2 trials, 30,392 participants; moderate-certainty), and probably reduce withdrawals due to adverse effects (3.9% versus 2.9%; RR 0.73, 95% CI 0.64 to 0.84; 3 trials, 25,254 participants; ARR 1.0%; moderate-certainty). Compared to first-line alpha-blockers, first-line thiazides probably result in little to no difference in total mortality (RR 0.98, 95% CI 0.88 to 1.09; 1 trial, 24,316 participants; moderate-certainty), probably reduce total cardiovascular events (12.1% versus 9.0%; RR 0.74, 95% CI 0.69 to 0.80; 2 trials, 24,396 participants; ARR 3.1%; moderate-certainty) and stroke (2.7% versus 2.3%; RR 0.86, 95% CI 0.73 to 1.01; 2 trials, 24,396 participants; ARR 0.4%; moderate-certainty), may result in little to no difference in CHD (RR 0.98, 95% CI 0.86 to 1.11; 2 trials, 24,396 participants; low-certainty), probably reduce heart failure (5.4% versus 2.8%; RR 0.51, 95% CI 0.45 to 0.58; 1 trial, 24,316 participants; ARR 2.6%; moderate-certainty), and may reduce withdrawals due to adverse effects (1.3% versus 0.9%; RR 0.70, 95% CI 0.54 to 0.89; 3 trials, 24,772 participants; ARR 0.4%; low-certainty). For the other drug classes, data were insufficient. No antihypertensive drug class demonstrated any clinically important advantages over first-line thiazides.

AUTHORS' CONCLUSIONS

When used as first-line agents for the treatment of hypertension, thiazides and thiazide-like drugs likely do not change total mortality and likely decrease some morbidity outcomes such as cardiovascular events and withdrawals due to adverse effects, when compared to beta-blockers, calcium channel blockers, ACE inhibitors, and alpha-blockers.

Calcium channel blockers versus other classes of drugs for hypertension

BACKGROUND

This is the first update of a review published in 2010. While calcium channel blockers (CCBs) are often recommended as a first-line drug to treat hypertension, the effect of CCBs on the prevention of cardiovascular events, as compared with other antihypertensive drug classes, is still debated.

OBJECTIVES

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

SEARCH METHODS

For this updated review, the Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials (RCTs) up to 1 September 2020: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL 2020, Issue 1), Ovid MEDLINE, Ovid Embase, the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted the authors of relevant papers regarding further published and unpublished work and checked the references of published studies to identify additional trials. The searches had no language restrictions.

SELECTION CRITERIA

Randomised controlled trials comparing first-line CCBs with other antihypertensive classes, with at least 100 randomised hypertensive participants and a follow-up of at least two years.

DATA COLLECTION AND ANALYSIS

Three review authors independently selected the included trials, evaluated the risk of bias, and entered the data for analysis. Any disagreements were resolved through discussion. We contacted study authors for additional information.

MAIN RESULTS

This update contains five new trials. We included a total of 23 RCTs (18 dihydropyridines, 4 non-dihydropyridines, 1 not specified) with 153,849 participants with hypertension. All-cause mortality was not different between first-line CCBs and any other antihypertensive classes. As compared to diuretics, CCBs probably increased  major cardiovascular events (risk ratio (RR) 1.05, 95% confidence interval (CI) 1.00 to 1.09, P = 0.03) and increased congestive heart failure events (RR 1.37, 95% CI 1.25 to 1.51, moderate-certainty evidence). As compared to beta-blockers, CCBs reduced the following outcomes: major cardiovascular events (RR 0.84, 95% CI 0.77 to 0.92), stroke (RR 0.77, 95% CI 0.67 to 0.88, moderate-certainty evidence), and cardiovascular mortality (RR 0.90, 95% CI 0.81 to 0.99, low-certainty evidence). As compared to angiotensin-converting enzyme (ACE) inhibitors, CCBs reduced stroke (RR 0.90, 95% CI 0.81 to 0.99, low-certainty evidence) and increased congestive heart failure (RR 1.16, 95% CI 1.06 to 1.28, low-certainty evidence). As compared to angiotensin receptor blockers (ARBs), CCBs reduced myocardial infarction (RR 0.82, 95% CI 0.72 to 0.94, moderate-certainty evidence) and increased congestive heart failure (RR 1.20, 95% CI 1.06 to 1.36, low-certainty evidence).

AUTHORS' CONCLUSIONS

For the treatment of hypertension, there is moderate certainty evidence that diuretics reduce major cardiovascular events and congestive heart failure more than CCBs. There is low to moderate certainty evidence that CCBs probably reduce major cardiovascular events more than beta-blockers. There is low to moderate certainty evidence that CCBs reduced stroke when compared to angiotensin-converting enzyme (ACE) inhibitors and reduced myocardial infarction when compared to angiotensin receptor blockers (ARBs), but increased congestive heart failure when compared to ACE inhibitors and ARBs. 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 individuals taking CCBs as compared with other antihypertensive drug classes are needed for patients with different stages of hypertension, different ages, and with different comorbidities such as diabetes.

Calcium channel blockers versus other classes of drugs for hypertension

BACKGROUND

This is the first update of a review published in 2010. While calcium channel blockers (CCBs) are often recommended as a first-line drug to treat hypertension, the effect of CCBs on the prevention of cardiovascular events, as compared with other antihypertensive drug classes, is still debated.

OBJECTIVES

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

SEARCH METHODS

For this updated review, the Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials (RCTs) up to 1 September 2020: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL 2020, Issue 1), Ovid MEDLINE, Ovid Embase, the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted the authors of relevant papers regarding further published and unpublished work and checked the references of published studies to identify additional trials. The searches had no language restrictions.

SELECTION CRITERIA

Randomised controlled trials comparing first-line CCBs with other antihypertensive classes, with at least 100 randomised hypertensive participants and a follow-up of at least two years.

DATA COLLECTION AND ANALYSIS

Three review authors independently selected the included trials, evaluated the risk of bias, and entered the data for analysis. Any disagreements were resolved through discussion. We contacted study authors for additional information.

MAIN RESULTS

This update contains five new trials. We included a total of 23 RCTs (18 dihydropyridines, 4 non-dihydropyridines, 1 not specified) with 153,849 participants with hypertension. All-cause mortality was not different between first-line CCBs and any other antihypertensive classes. As compared to diuretics, CCBs probably increased  major cardiovascular events (risk ratio (RR) 1.05, 95% confidence interval (CI) 1.00 to 1.09, P = 0.03) and increased congestive heart failure events (RR 1.37, 95% CI 1.25 to 1.51, moderate-certainty evidence). As compared to beta-blockers, CCBs reduced the following outcomes: major cardiovascular events (RR 0.84, 95% CI 0.77 to 0.92), stroke (RR 0.77, 95% CI 0.67 to 0.88, moderate-certainty evidence), and cardiovascular mortality (RR 0.90, 95% CI 0.81 to 0.99, low-certainty evidence). As compared to angiotensin-converting enzyme (ACE) inhibitors, CCBs reduced stroke (RR 0.90, 95% CI 0.81 to 0.99, low-certainty evidence) and increased congestive heart failure (RR 1.16, 95% CI 1.06 to 1.28, low-certainty evidence). As compared to angiotensin receptor blockers (ARBs), CCBs reduced myocardial infarction (RR 0.82, 95% CI 0.72 to 0.94, moderate-certainty evidence) and increased congestive heart failure (RR 1.20, 95% CI 1.06 to 1.36, low-certainty evidence).

AUTHORS' CONCLUSIONS

For the treatment of hypertension, there is moderate certainty evidence that diuretics reduce major cardiovascular events and congestive heart failure more than CCBs. There is low to moderate certainty evidence that CCBs probably reduce major cardiovascular events more than beta-blockers. There is low to moderate certainty evidence that CCBs reduced stroke when compared to angiotensin-converting enzyme (ACE) inhibitors and reduced myocardial infarction when compared to angiotensin receptor blockers (ARBs), but increased congestive heart failure when compared to ACE inhibitors and ARBs. 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 individuals taking CCBs as compared with other antihypertensive drug classes are needed for patients with different stages of hypertension, different ages, and with different comorbidities such as diabetes.

The effect of taking blood pressure lowering medication at night on cardiovascular disease risk. A systematic review

To investigate the effect of night-time BP-lowering drug treatment on the risk of major CVD and mortality, we systematically reviewed randomized controlled trials comparing night-time versus morning dosing. Two studies were found relevant to the clinical question (the MAPEC and Hygia trials). They were similar in study design and population and were conducted by the same study group. As the Hygia trial had more power with a significantly larger sample size, we did not perform a meta-analysis. Both studies reported a reduction of ~50% in major CVD events and all-cause mortality with night-time dosing and a reduction of 60% in CVD mortality. The results from these studies support the implementation of night-time BP-lowering drug treatment in the prevention of CVD and mortality. However there is an on-going discussion on the validity and methodology of MAPEC and Hygia trials, the interpretation of the results should be cautious. Stronger evidence is needed prior to changing clinical practice. Questions that remain to be answered relate to the generalisability of the results across different populations at different levels of BP related risk and the importance of morning versus evening timing of medication on CVD prevention as determined though a well-designed randomised controlled trial.

Antihypertensive treatment and risk of cancer: an individual participant data meta-analysis

BACKGROUND

Some studies have suggested a link between antihypertensive medication and cancer, but the evidence is so far inconclusive. Thus, we aimed to investigate this association in a large individual patient data meta-analysis of randomised clinical trials.

METHODS

We searched PubMed, MEDLINE, The Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov from Jan 1, 1966, to Sept 1, 2019, to identify potentially eligible randomised controlled trials. Eligible studies were randomised controlled trials comparing one blood pressure lowering drug class with a placebo, inactive control, or other blood pressure lowering drug. We also required that trials had at least 1000 participant years of follow-up in each treatment group. Trials without cancer event information were excluded. We requested individual participant data from the authors of eligible trials. We pooled individual participant-level data from eligible trials and assessed the effects of angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), β blockers, calcium channel blockers, and thiazide diuretics on cancer risk in one-stage individual participant data and network meta-analyses. Cause-specific fixed-effects Cox regression models, stratified by trial, were used to calculate hazard ratios (HRs). The primary outcome was any cancer event, defined as the first occurrence of any cancer diagnosed after randomisation. This study is registered with PROSPERO (CRD42018099283).

FINDINGS

33 trials met the inclusion criteria, and included 260 447 participants with 15 012 cancer events. Median follow-up of included participants was 4·2 years (IQR 3·0-5·0). In the individual participant data meta-analysis comparing each drug class with all other comparators, no associations were identified between any antihypertensive drug class and risk of any cancer (HR 0·99 [95% CI 0·95-1·04] for ACEIs; 0·96 [0·92-1·01] for ARBs; 0·98 [0·89-1·07] for β blockers; 1·01 [0·95-1·07] for thiazides), with the exception of calcium channel blockers (1·06 [1·01-1·11]). In the network meta-analysis comparing drug classes against placebo, we found no excess cancer risk with any drug class (HR 1·00 [95% CI 0·93-1·09] for ACEIs; 0·99 [0·92-1·06] for ARBs; 0·99 [0·89-1·11] for β blockers; 1·04 [0·96-1·13] for calcium channel blockers; 1·00 [0·90-1·10] for thiazides).

INTERPRETATION

We found no consistent evidence that antihypertensive medication use had any effect on cancer risk. Although such findings are reassuring, evidence for some comparisons was insufficient to entirely rule out excess risk, in particular for calcium channel blockers.

FUNDING

British Heart Foundation, National Institute for Health Research, Oxford Martin School.

Treatment with enalapril and not diltiazem ameliorated progression of chronic kidney disease in rats, and normalized renal AT1 receptor expression as measured with PET imaging

ACE inhibitors are considered first line of treatment in patients with many forms of chronic kidney disease (CKD). Other antihypertensives such as calcium channel blockers achieve similar therapeutic effectiveness in attenuating hypertension-related renal damage progression. Our objective was to explore the value of positron emission tomography (PET) imaging of renal AT1 receptor (AT1R) to guide therapy in the 5/6 subtotal-nephrectomy (Nx) rat model of CKD. Ten weeks after Nx, Sprague-Dawley rats were administered 10mg/kg/d enalapril (NxE), 30mg/kg/d diltiazem (NxD) or left untreated (Nx) for an additional 8-10 weeks. Kidney AT1R expression was assessed using in vivo [18F]fluoropyridine-losartan PET and in vitro autoradiography. Compared to shams, Nx rats exhibited higher systolic blood pressure that was reduced by both enalapril and diltiazem. At 18-20 weeks, plasma creatinine and albuminuria were significantly increased in Nx, reduced to sham levels in NxE, but enhanced in NxD rats. Enalapril treatment decreased kidney angiotensin II whereas diltiazem induced significant elevations in plasma and kidney levels. Reduced PET renal AT1R levels in Nx were normalized by enalapril but not diltiazem, and results were supported by autoradiography. Reduction of renal blood flow in Nx was restored by enalapril, while no difference was observed in myocardial blood flow amongst groups. Enhanced left ventricle mass in Nx was not reversed by enalapril but was augmented with diltiazem. Stroke volume was diminished in untreated Nx compared to shams and restored with both therapies. [18F]Fluoropyridine-Losartan PET allowed in vivo quantification of kidney AT1R changes associated with progression of CKD and with various pharmacotherapies.

Beta-blockers for hypertension

BACKGROUND

Beta-blockers refer to a mixed group of drugs with diverse pharmacodynamic and pharmacokinetic properties. They have shown long-term beneficial effects on mortality and cardiovascular disease (CVD) when used in people with heart failure or acute myocardial infarction. Beta-blockers were thought to have similar beneficial effects when used as first-line therapy for hypertension. However, the benefit of beta-blockers as first-line therapy for hypertension without compelling indications is controversial. This review is an update of a Cochrane Review initially published in 2007 and updated in 2012.

OBJECTIVES

To assess the effects of beta-blockers on morbidity and mortality endpoints in adults with hypertension.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to June 2016: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 6), MEDLINE (from 1946), Embase (from 1974), and ClinicalTrials.gov. We checked reference lists of relevant reviews, and reference lists of studies potentially eligible for inclusion in this review, and also searched the the World Health Organization International Clinical Trials Registry Platform on 06 July 2015.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of at least one year of duration, which assessed the effects of beta-blockers compared to placebo or other drugs, as first-line therapy for hypertension, on mortality and morbidity in adults.

DATA COLLECTION AND ANALYSIS

We selected studies and extracted data in duplicate, resolving discrepancies by consensus. We expressed study results as risk ratios (RR) with 95% confidence intervals (CI) and conducted fixed-effect or random-effects meta-analyses, as appropriate. We also used GRADE to assess the certainty of the evidence. GRADE classifies the certainty of evidence as high (if we are confident that the true effect lies close to that of the estimate of effect), moderate (if the true effect is likely to be close to the estimate of effect), low (if the true effect may be substantially different from the estimate of effect), and very low (if we are very uncertain about the estimate of effect).

MAIN RESULTS

Thirteen RCTs met inclusion criteria. They compared beta-blockers to placebo (4 RCTs, 23,613 participants), diuretics (5 RCTs, 18,241 participants), calcium-channel blockers (CCBs: 4 RCTs, 44,825 participants), and renin-angiotensin system (RAS) inhibitors (3 RCTs, 10,828 participants). These RCTs were conducted between the 1970s and 2000s and most of them had a high risk of bias resulting from limitations in study design, conduct, and data analysis. There were 40,245 participants taking beta-blockers, three-quarters of them taking atenolol. We found no outcome trials involving the newer vasodilating beta-blockers (e.g. nebivolol).There was no difference in all-cause mortality between beta-blockers and placebo (RR 0.99, 95% CI 0.88 to 1.11), diuretics or RAS inhibitors, but it was higher for beta-blockers compared to CCBs (RR 1.07, 95% CI 1.00 to 1.14). The evidence on mortality was of moderate-certainty for all comparisons.Total CVD was lower for beta-blockers compared to placebo (RR 0.88, 95% CI 0.79 to 0.97; low-certainty evidence), a reflection of the decrease in stroke (RR 0.80, 95% CI 0.66 to 0.96; low-certainty evidence) since there was no difference in coronary heart disease (CHD: RR 0.93, 95% CI 0.81 to 1.07; moderate-certainty evidence). The effect of beta-blockers on CVD was worse than that of CCBs (RR 1.18, 95% CI 1.08 to 1.29; moderate-certainty evidence), but was not different from that of diuretics (moderate-certainty) or RAS inhibitors (low-certainty). In addition, there was an increase in stroke in beta-blockers compared to CCBs (RR 1.24, 95% CI 1.11 to 1.40; moderate-certainty evidence) and RAS inhibitors (RR 1.30, 95% CI 1.11 to 1.53; moderate-certainty evidence). However, there was little or no difference in CHD between beta-blockers and diuretics (low-certainty evidence), CCBs (moderate-certainty evidence) or RAS inhibitors (low-certainty evidence). In the single trial involving participants aged 65 years and older, atenolol was associated with an increased CHD incidence compared to diuretics (RR 1.63, 95% CI 1.15 to 2.32). Participants taking beta-blockers were more likely to discontinue treatment due to adverse events than participants taking RAS inhibitors (RR 1.41, 95% CI 1.29 to 1.54; moderate-certainty evidence), but there was little or no difference with placebo, diuretics or CCBs (low-certainty evidence).

AUTHORS' CONCLUSIONS

Most outcome RCTs on beta-blockers as initial therapy for hypertension have high risk of bias. Atenolol was the beta-blocker most used. Current evidence suggests that initiating treatment of hypertension with beta-blockers leads to modest CVD reductions and little or no effects on mortality. These beta-blocker effects are inferior to those of other antihypertensive drugs. Further research should be of high quality and should explore whether there are differences between different subtypes of beta-blockers or whether beta-blockers have differential effects on younger and older people.

Beta-blockers for hypertension

BACKGROUND

This review is an update of the Cochrane Review published in 2007, which assessed the role of beta-blockade as first-line therapy for hypertension.

OBJECTIVES

To quantify the effectiveness and safety of beta-blockers on morbidity and mortality endpoints in adults with hypertension.

SEARCH METHODS

In December 2011 we searched the Cochrane Central Register of Controlled Trials, Medline, Embase, and reference lists of previous reviews; for eligible studies published since the previous search we conducted in May 2006.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of at least one year duration, which assessed the effects of beta-blockers compared to placebo or other drugs, as first-line therapy for hypertension, on mortality and morbidity in adults.

DATA COLLECTION AND ANALYSIS

We selected studies and extracted data in duplicate. We expressed study results as risk ratios (RR) with 95% confidence intervals (CI) and combined them using the fixed-effects or random-effects method, as appropriate.

MAIN RESULTS

We included 13 RCTs which compared beta-blockers to placebo (4 trials, N=23,613), diuretics (5 trials, N=18,241), calcium-channel blockers (CCBs: 4 trials, N=44,825), and renin-angiotensin system (RAS) inhibitors (3 trials, N=10,828). Three-quarters of the 40,245 participants on beta-blockers used atenolol. Most studies had a high risk of bias; resulting from various limitations in study design, conduct, and data analysis.Total mortality was not significantly different between beta-blockers and placebo (RR 0.99, 95%CI 0.88 to 1.11; I(2)=0%), diuretics or RAS inhibitors, but was higher for beta-blockers compared to CCBs (RR 1.07, 95%CI 1.00 to 1.14; I(2)=2%). Total cardiovascular disease (CVD) was lower for beta-blockers compared to placebo (RR 0.88, 95%CI 0.79 to 0.97; I(2)=21%). This is primarily a reflection of the significant decrease in stroke (RR 0.80, 95%CI 0.66 to 0.96; I(2)=0%), since there was no significant difference in coronary heart disease (CHD) between beta-blockers and placebo. There was no significant difference in withdrawals from assigned treatment due to adverse events between beta-blockers and placebo (RR 1.12, 95%CI 0.82 to 1.54; I(2)=66%).The effect of beta-blockers on CVD was significantly worse than that of CCBs (RR 1.18, 95%CI 1.08-1.29; I(2)=0%), but was not different from that of diuretics or RAS inhibitors. In addition, there was an increase in stroke in beta-blockers compared to CCBs (RR 1.24, 95%CI 1.11-1.40; I(2)=0%) and RAS inhibitors (RR 1.30, 95%CI 1.11 to 1.53; I(2)=29%). However, CHD was not significantly different between beta-blockers and diuretics, CCBs or RAS inhibitors. Participants on beta-blockers were more likely to discontinue treatment due to adverse events than those on RAS inhibitors (RR 1.41, 95% CI 1.29 to 1.54; I(2)=12%), but there was no significant difference with diuretics or CCBs.

AUTHORS' CONCLUSIONS

Initiating treatment of hypertension with beta-blockers leads to modest reductions in cardiovascular disease and no significant effects on mortality. These effects of beta-blockers are inferior to those of other antihypertensive drugs. The GRADE quality of this evidence is low, implying that the true effect of beta-blockers may be substantially different from the estimate of effects found in this review. Further research should be of high quality and should explore whether there are differences between different sub-types of beta-blockers or whether beta-blockers have differential effects on younger and elderly patients.

Beta-blockers for hypertension

BACKGROUND

This review is an update of the Cochrane Review published in 2007, which assessed the role of beta-blockade as first-line therapy for hypertension.

OBJECTIVES

To quantify the effectiveness and safety of beta-blockers on morbidity and mortality endpoints in adults with hypertension.

SEARCH METHODS

In December 2011 we searched the Cochrane Central Register of Controlled Trials, Medline, Embase, and reference lists of previous reviews; for eligible studies published since the previous search we conducted in May 2006.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of at least one year duration, which assessed the effects of beta-blockers compared to placebo or other drugs, as first-line therapy for hypertension, on mortality and morbidity in adults.

DATA COLLECTION AND ANALYSIS

We selected studies and extracted data in duplicate. We expressed study results as risk ratios (RR) with 95% confidence intervals (CI) and combined them using the fixed-effects or random-effects method, as appropriate.

MAIN RESULTS

We included 13 RCTs which compared beta-blockers to placebo (4 trials, N=23,613), diuretics (5 trials, N=18,241), calcium-channel blockers (CCBs: 4 trials, N=44,825), and renin-angiotensin system (RAS) inhibitors (3 trials, N=10,828). Three-quarters of the 40,245 participants on beta-blockers used atenolol. Most studies had a high risk of bias; resulting from various limitations in study design, conduct, and data analysis.Total mortality was not significantly different between beta-blockers and placebo (RR 0.99, 95%CI 0.88 to 1.11; I(2)=0%), diuretics or RAS inhibitors, but was higher for beta-blockers compared to CCBs (RR 1.07, 95%CI 1.00 to 1.14; I(2)=2%). Total cardiovascular disease (CVD) was lower for beta-blockers compared to placebo (RR 0.88, 95%CI 0.79 to 0.97; I(2)=21%). This is primarily a reflection of the significant decrease in stroke (RR 0.80, 95%CI 0.66 to 0.96; I(2)=0%), since there was no significant difference in coronary heart disease (CHD) between beta-blockers and placebo. There was no significant difference in withdrawals from assigned treatment due to adverse events between beta-blockers and placebo (RR 1.12, 95%CI 0.82 to 1.54; I(2)=66%).The effect of beta-blockers on CVD was significantly worse than that of CCBs (RR 1.18, 95%CI 1.08-1.29; I(2)=0%), but was not different from that of diuretics or RAS inhibitors. In addition, there was an increase in stroke in beta-blockers compared to CCBs (RR 1.24, 95%CI 1.11-1.40; I(2)=0%) and RAS inhibitors (RR 1.30, 95%CI 1.11 to 1.53; I(2)=29%). However, CHD was not significantly different between beta-blockers and diuretics, CCBs or RAS inhibitors. Participants on beta-blockers were more likely to discontinue treatment due to adverse events than those on RAS inhibitors (RR 1.41, 95% CI 1.29 to 1.54; I(2)=12%), but there was no significant difference with diuretics or CCBs.

AUTHORS' CONCLUSIONS

Initiating treatment of hypertension with beta-blockers leads to modest reductions in cardiovascular disease and no significant effects on mortality. These effects of beta-blockers are inferior to those of other antihypertensive drugs. The GRADE quality of this evidence is low, implying that the true effect of beta-blockers may be substantially different from the estimate of effects found in this review. Further research should be of high quality and should explore whether there are differences between different sub-types of beta-blockers or whether beta-blockers have differential effects on younger and elderly patients.

Evening versus morning dosing regimen drug therapy for hypertension

BACKGROUND

Variation in blood pressure levels display circadian rhythms. The morning surge in blood pressure is known to increase the risk of myocardial events in the first several hours post awakening. A systematic review of the administration-time-related-effects of evening versus morning dosing regimen of antihypertensive drugs in the management of patients with primary hypertension has not been conducted.

OBJECTIVES

To evaluate the administration-time-related-effects of antihypertensive drugs administered as once daily monotherapy in the evening versus morning administration regimen on all cause mortality, cardiovascular morbidity and reduction of blood pressure in patients with primary hypertension.

SEARCH STRATEGY

We searched Cochrane CENTRAL on Ovid (4th Quarter 2009), Ovid MEDLINE (1950 to October 2009), EMBASE (1974 to October 2009), the Chinese Biomedical literature database (1978 to 2009) and the reference lists of relevant articles. No language restrictions were applied.

SELECTION CRITERIA

Randomized controlled trials comparing the administration-time-related effects of evening with morning dosing monotherapy regimens in patients with primary hypertension were included. Patients with known secondary hypertension, shift workers or white coat hypertension were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed trial quality. Disagreements were resolved by discussion or a third reviewer. Data synthesis and analysis were done using RevMan 5.1. Random effects meta-analysis and sensitivity analysis were conducted.

MAIN RESULTS

21 randomized controlled trials (RCTs) in 1,993 patients with primary hypertension met the inclusion criteria for this review - ACEIs (5 trials), CCBs (7 trials), ARBs (6 trials), diuretics (2 trials), alpha-blockers (1 trial), and beta-blockers (1 trial). Meta-analysis showed significant heterogeneity across trials.No RCT reported on all cause mortality, cardiovascular mortality, cardiovascular morbidity and serious adverse events.There was no statistically significant difference for overall adverse events (RR=0.78, 95%CI: 0.37 to 1.65) and withdrawals due to adverse events (RR=0.53, 95%CI: 0.26 to 1.07).No significant differences were noted for morning SBP (-1.62 mm Hg, 95% CI: -4.19 to 0.95) and morning DBP (-1.21 mm Hg, 95% CI: -3.28 to 0.86); but 24-hour BP (SBP: -1.71 mm Hg, 95% CI: -2.78 to -0.65; DBP: -1.38 mm Hg, 95% CI: -2.13 to -0.62) showed a statistically significant difference.

AUTHORS' CONCLUSIONS

No RCT reported on clinically relevant outcome measures - all cause mortality, cardiovascular morbidity and morbidity. There were no significant differences in overall adverse events and withdrawals due to adverse events among the evening versus morning dosing regimens. In terms of BP lowering efficacy, for 24-hour SBP and DBP, the data suggests that better blood pressure control was achieved with bedtime dosing than morning administration of antihypertensive medication, the clinical significance of which is not known.

Morbidity and mortality of orthostatic hypotension: implications for management of cardiovascular disease

Orthostatic hypotension (OH) is the failure of cardiovascular reflexes to maintain blood pressure on standing from a supine or sitting position. Although OH may cause symptoms of dizziness or syncope, asymptomatic OH (AOH) is far more common and is an independent risk factor for mortality and cardiovascular disease (CVD). The prevalence of AOH increases with age, the presence of hypertension or diabetes and the use of antihypertensive or other medications. The implications of AOH for the treatment of CVD and hypertension are not well defined. This review provides an overview of the current information on this topic and recommends the more frequent assessment of OH in clinical practice and in future clinical trials.

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.

Chronobiology and chronotherapy of ischemic heart disease

The occurrence of the clinical manifestations of ischemic heart disease (IHD)--myocardial ischemia and angina pectoris, acute myocardial infarction, and sudden cardiac death--is unevenly distributed during the 24 h with greater than expected events during the initial hours of the daily activity span and in the late afternoon or early evening. Such temporal patterns result from circadian rhythms in pathophysiological mechanisms plus cyclic environmental stressors that trigger ischemic events. Both the pharmacokinetics (PK) and pharmacodynamics (PD) of many, though not all, anti-ischemic oral nitrate, calcium channel blocker, and beta-adrenoceptor antagonist medications have been shown to be influenced by the circadian time of their administration. The requirement for preventive and therapeutic interventions varies predictably during the 24 h, and thus therapeutic strategies should also be tailored accordingly to optimize outcomes. During the past decade, two first generation calcium channel blocker chronotherapies have been developed, trialed, and marketed in North America for the improved treatment of IHD. Nonetheless, there has been relatively little investigation of the administration-time (circadian rhythm) dependencies of the PK and PD of conventional anti-ischemic medications, and there has been little progress in the development of new generation IHD chronotherapies. Available epidemiologic, pharmacologic, and clinico-therapeutic evidence demonstrates how the chronobiologic approach to IHD can contribute new insight and opportunities to improve drug design and drug delivery to enhance therapeutic outcomes.

Chronobiology, drug delivery, and chronotherapeutics

Biological processes and functions are organized in space, as a physical anatomy, and time, as a biological time structure. The latter is expressed by short-, intermediate-, and long-period oscillations, i.e., biological rhythms. The circadian (24-h) time structure has been most studied and shows great importance to the practice of medicine and pharmacotherapy of patients. The phase and amplitude of key physiological and biochemical circadian rhythms contribute to the known predictable-in-time patterns in the occurrence of serious and life-threatening medical events, like myocardial infraction and stroke, and the manifestation and severity of symptoms of chronic diseases, like allergic rhinitis, asthma, and arthritis. Moreover, body rhythms can significantly affect responses of patients to diagnostic tests and, most important to the theme of this special issue, medications. Rhythmicity in the pathophysiology of disease is one basis for chronotherapeutics--purposeful variation in time of the concentration of medicines in synchrony with biological rhythm determinants of disease activity--to optimize treatment outcomes. A second basis is the control of undesired effects of medications, especially when the therapeutic range is narrow and the potential for adverse effects high, which is the case for cancer drugs. A third basis is to meet the biological requirements for frequency-modulated drug delivery, which is the case for certain neuroendocrine peptide analogues. Great progress has been realized with hydrogels, and they offer many advantages and opportunities in the design of chronotherapeutic systems for drug delivery via the oral, buccal, nasal, subcutaneous, transdermal, rectal, and vaginal routes. Nonetheless, innovative delivery systems will be necessary to ensure optimal application of chronotherapeutic interventions. Next generation drug-delivery systems must be configurable so they (i) require minimal volitional adherence, (ii) respond to sensitive biomarkers of disease activity that often vary in time as periodic (circadian rhythmic) and non-periodic (random) patterns to release medication to targeted tissue(s) on a real time as needed basis, and (iii) are cost-effective.

Hypertension patients participating in trials differ in many aspects from patients treated in general practices

OBJECTIVE

To determine to what extent participants in randomized controlled hypertension trials (RCTs) could be compared to patients with hypertension in general practices.

STUDY DESIGN AND SETTING

We analyzed RCTs that had been used in hypertension guidelines or were available for future hypertension guidelines. The characteristics of the participants of these RCTs were compared with those of the patients with hypertension in general practices. In addition, inclusion and exclusion criteria of the RCTs were applied to the hypertension patients in the general practices.

RESULTS

Twenty-one trials were analyzed. Participants' characteristics often differed from those of the patients with hypertension in general practices, in particular in the older trials where the participants showed lower cardiovascular risk. More recent trials showed participants' profiles that better reflected those of the patients under treatment in a general practice. Less than half of the patients undergoing treatment in a general practice would have been included in the hypertension trials.

CONCLUSION

Participants taking part in trials differed from patients with hypertension in a general practice in a number of important aspects. This hampers their external validity. Inclusion of participants with comorbidity and other general practice characteristics would improve translation of study findings to daily practice recommendations.

Beta-blockers for hypertension

BACKGROUND

Two recent systematic reviews found first-line beta-blockers to be less effective in reducing the incidence of stroke and the combined endpoint of stroke, myocardial infarction, and death compared to all other antihypertensive drugs taken together. However, beta-blockers might be better or worse than a specific class of drugs for a particular outcome measure so that comparing beta-blockers with all other classes taken together could be misleading. In addition, these systematic reviews did not assess the tolerability of beta-blockers relative to other antihypertensive medications. We thus undertook this review to re-assess the place of beta-blockade as first-line therapy for hypertension relative to each of the other major classes of antihypertensive drugs.

OBJECTIVES

To quantify the effectiveness and safety of beta-blockers on morbidity and mortality endpoints in adults with hypertension.

SEARCH STRATEGY

We searched eligible studies up to June 2006 in the Cochrane Controlled Trials Register, Medline, Embase, and reference lists of previous reviews, and by contacting hypertension experts.

SELECTION CRITERIA

We selected randomised controlled trials which assessed the effectiveness of beta-blockers compared to placebo, no therapy or other drug classes, as monotherapy or first-line therapy for hypertension, on mortality and morbidity endpoints in men and non-pregnant women aged 18 years or older.

DATA COLLECTION AND ANALYSIS

At least two authors independently applied study selection criteria, assessed study quality, and extracted data; with differences resolved by consensus. We expressed study results as relative risks (RR) with 95% confidence intervals (CI) and conducted quantitative analyses with trial participants in groups to which they were randomly allocated, regardless of which or how much treatment they actually received. In the absence of significant heterogeneity between studies (p>0.1), we performed meta-analysis using a fixed effects method. Otherwise, we used the random effects method and investigated the cause of heterogeneity by stratified analysis. In addition, we used the Higgins statistic (I(2)) to quantify the amount of between-study variability in effect attributable to true heterogeneity rather than chance.

MAIN RESULTS

Thirteen randomised controlled trials (N=91,561 participants), which met our inclusion criteria, compared beta-blockers to placebo or no treatment (4 trials with 23,613 participants), diuretics (5 trials with 18,241 participants), calcium-channel blockers (CCBs: 4 trials with 44,825 participants), and renin-angiotensin system (RAS) inhibitors (3 trials with 10,828 participants). The risk of all-cause mortality was not different between first-line beta-blockers and placebo (RR 0.99, 95%CI 0.88 to 1.11, I(2)=0%), diuretics or RAS inhibitors, but was higher for beta-blockers compared to CCBs (RR 1.07, 95%CI 1.00 to 1.14, I(2)=2.2%; ARI=0.5%, NNH=200). The risk of total cardiovascular disease (CVD) was lower for first-line beta-blockers compared to placebo (RR 0.88, 95%CI 0.79 to 0.97, I(2)=21.4%, ARR=0.7%, NNT=140). This is primarily a reflection of the significant decrease in stroke (RR 0.80, 95%CI 0.66 to 0.96; I(2)=0%; ARR=0.5%, NNT=200); coronary heart disease (CHD) risk was not significantly different between beta-blockers and placebo. The effect of beta-blockers on CVD was significantly worse than that of CCBs (RR 1.18, 95%CI 1.08 to 1.29, I(2)=0%; ARI=1.3%, NNH=80), but was not significantly different from that of diuretics or RAS inhibitors. Increased total CVD was due to an increase in stroke compared to CCBs (RR 1.24, 95%CI 1.11 to 1.40, I(2)=0%; ARI=0.6%, NNH=180). There was also an increase in stroke with beta-blockers as compared to RAS inhibitors (RR 1.30, 95%CI 1.11 to 1.53, I(2)=29.1%; ARI=1.5%, NNH=65). CHD was not significantly different between beta-blockers and diuretics or CCBs or RAS inhibitors. In addition, patients on beta-blockers were more likely to discontinue treatment due to side effects than those on diuretics (RR 1.86, 95%CI 1.39 to 2.50, I(2)=78.2%, ARI=6.4% NNH=16) and RAS inhibitors (RR 1.41, 95%CI 1.29 to 1.54, I(2)=12.1%; ARI=5.5%, NNH=18), but there was no significant difference with CCBs.

AUTHORS' CONCLUSIONS

The available evidence does not support the use of beta-blockers as first-line drugs in the treatment of hypertension. This conclusion is based on the relatively weak effect of beta-blockers to reduce stroke and the absence of an effect on coronary heart disease when compared to placebo or no treatment. More importantly, it is based on the trend towards worse outcomes in comparison with calcium-channel blockers, renin-angiotensin system inhibitors, and thiazide diuretics. Most of the evidence for these conclusions comes from trials where atenolol was the beta-blocker used (75% of beta-blocker participants in this review). However, it is not known at present whether beta-blockers have differential effects on younger and elderly patients or whether there are differences between the different sub-types of beta-blockers.

Sample size calculation in survival trials accounting for time-varying relationship between noncompliance and risk of outcome event

BACKGROUND

Most methods of sample size calculations for survival trials adjust the estimated outcome event rates for noncompliance based on the assumption that non-compliance is independent of the risk of the outcome event although there has been published evidence that noncompliers are often at a higher risk than compliers. More recent work has started to consider the situations of informative noncompliance and different risks for noncompliers. However, the possibility of a time-varying association between noncompliance and risk has been ignored. Our analysis indicated a strong time-varying relationship between noncompliance defined as permanent discontinuation of study treatments and risk of the outcome event in the CONVINCE trial.

PURPOSE

The purpose of this research is to develop methods for the log-rank sample size calculations for two-arm clinical trials that allow for the relationship between risk and noncompliance to vary over time and to study how sample size requirements vary with different patterns of the time relationship.

METHODS

The method developed takes Lakatos' Markov chain approach as a basis, modifying it to incorporate time dynamics, and emphasizing permanent discontinuation of study medication as the form of noncompliance to be considered.

RESULTS

Results with our method show that sample size depends on the relative rates of noncompliance in the two arms, the hazard for the outcome event following non-compliance, whether it involves switching to the hazard of the opposite arm or is common to both arms, and whether noncompliance occurs early or late in the trial. These factors interact with each other in complex ways, precluding simple summaries.

LIMITATIONS

This research focuses on two-arm clinical trials with time to event as primary outcome measure. The method developed is not directly applicable to trials with more complicated designs and/or trials with other types of primary outcome.

CONCLUSIONS

The pattern of the relationship between noncompliance and risk can have a dramatic impact on the sample size and power calculations in survival studies. The method introduced provides a useful tool for investigators to explore the optimal sample size accounting for various dynamic associations between noncompliance and risk.

Methods underpinning national clinical guidelines for hypertension: describing the evidence shortfall

BACKGROUND

To be useful, clinical practice guidelines need to be evidence based; otherwise they will not achieve the validity, reliability and credibility required for implementation.

METHODS

This paper compares the methods used in gathering, analysing and linking of evidence to guideline recommendations in ten current hypertension guidelines.

RESULTS

It found several guidelines had failed to implement methods of searching for the relevant literature, critical analysis and linking to recommendations that minimise the risk of bias in the interpretation of research evidence. The more rigorous guidelines showed discrepancies in recommendations and grading that reflected different approaches to the use of evidence in guideline development.

CONCLUSION

Clinical practice guidelines as a methodology are clearly still an evolving health care technology.

Results of the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) trial by geographical region

OBJECTIVE

To examine regional differences in the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) trial.

DESIGN

Double-blind, randomized, international clinical trial.

SETTING

Six hundred and sixty-one clinical centers in 15 countries.

PATIENTS

Hypertensive volunteers (n = 16,602) with > or =1 additional cardiovascular risk factor, grouped into four regions: USA (n = 8144), Canada (n = 3405), Western Europe (Spain, UK, Italy, Sweden, Germany; n = 2048) or 'other' (Bulgaria, Israel, Mexico, Czech Republic, Hungary, Poland, Slovakia, Brazil; n = 2879); subgroupings included country and state/province within the USA and Canada.

INTERVENTIONS

Randomized to COER-verapamil or the investigator's choice of either atenolol or hydrochlorothiazide, titrated and additional drugs added as required.

MAIN OUTCOME MEASURES

Baseline characteristics; blood pressure control, medication adherence and lost-to-follow-up at 2 years; and composite primary endpoint (stroke, myocardial infarction, cardiovascular death) by regional groupings.

RESULTS

Regional differences were found at baseline for age, gender, blood pressure, percentage receiving antihypertensive drug therapy, initial choice of atenolol or hydrochlorothiazide, and risk factor profile. Blood pressure control rates increased markedly during follow-up in all regions, but varied significantly by region. Blood pressure control, medication adherence and lost-to-follow-up rates were poorest in the USA. After adjustment for baseline differences, the primary-event rate for each region was significantly lower than for the USA. Although baseline factors, blood pressure control and event rates varied by region, treatment differences did not.

CONCLUSION

Despite differences in baseline and follow-up measures across geographical regions, the absence of treatment differences by region suggests that the overall findings of CONVINCE are robust.

The role of existing and newer calcium channel blockers in the treatment of hypertension

Calcium channel blockers (CCBs), which include both dihydropyridines such as nifedipine and amlodipine and non-dihydropyridines (verapamil and diltiazem), are among the most widely prescribed agents for the management of essential hypertension. Several large outcome risk trials and comprehensive meta-analyses have found that CCBs reduce the cardiovascular morbidity and mortality associated with uncontrolled hypertension, including stroke. CCBs, however, appear less effective than angiotensin-converting enzyme inhibitors and diuretics for preventing heart failure and myocardial infarction. CCBs are among the agents listed as potential first-line therapy, either alone or in combination with other agents in hypertension management guidelines. Furthermore, CCBs are suitable for add-on therapy in combination with diuretics, angiotensin-converting enzyme inhibitors, and angiotensin-II receptor blockers. CCBs may be partially suitable for patients with comorbid Raynaud's syndrome, isolated systolic hypertension (dihydropyridine), or angina pectoris (non-dihydropyridine). The newer inherently long-acting dihydropyridine agents (e.g., lacidipine, lercanidipine), which are not currently available in the United States, appear to have comparable efficacy to older agents of the dihydropyridine class but may have an improved tolerability profile, especially with regard to peripheral edema.

Blood Pressure Reduction and Cardiovascular Prevention: An Update Including the 2003-2004 Secondary Prevention Trials

In a meta-analysis published in June 2003, we reported that new and old classes of antihypertensive drugs had similar long-term efficacy and safety. Furthermore, we observed that in clinical trials in hypertensive or high-risk patients gradients in systolic blood pressure (SBP) accounted for most differences in outcome. To test whether our previous conclusions would hold, we updated our quantitative overview with new information from clinical trials published before 2005. To compare new and old antihypertensive drugs, we computed pooled odds ratios from stratified 2 x 2 contingency tables. In a meta-regression analysis, we correlated these odds ratios with corresponding between-group differences in SBP. We then contrasted observed odds ratios with those predicted from gradients in SBP. The main finding of our overview was that reduction in SBP largely explained cardiovascular outcomes in the recently published actively controlled trials in hypertensive patients and in placebo-controlled secondary prevention trials. The published results suggested that dihydropyridine calcium-channel blockers might offer a selective benefit in the prevention of stroke and inhibitors of the renin-angiotensin system in the prevention of heart failure. For prevention of myocardial infarction, the published results were more equivocal, because of the benefit of amlodipine over placebo or valsartan in 2 trials, whereas other placebo-controlled trials of calcium-channel blockers or angiotensin converting enzyme inhibitors did not substantiate the expected benefit with regard to cardiac outcomes. In conclusion, the hypothesis that new antihypertensive drugs might influence cardiovascular prognosis over and beyond their antihypertensive effect remains unproven. Our overview emphasizes the need of tight blood pressure control, but does not allow determining to what extent blood pressure must be lowered for optimal cardiovascular prevention.

Chronotherapeutics:A surge of ideas

Chronotherapeutics is advancing hypertension treatments beyond once-daily dosing by synchronizing the maximum levels of medication during times when cardiovascular risk is highest. It has long been established that patients are at higher risk for cardiovascular events-including myocardial infarction, stroke, and sudden death-in the early morning hours. Using novel oral delivery methods, chronotherapeutic medication synchronizes the delivery of blood pressure drug within the period of rates risk, significantly reducing both absolute blood pressure numbers and, especially important, the rate of blood pressure increase. These therapies have also shown the ability to maintain adequate blood pressure levels during the trough period. Several blood pressure medications now have chronotherapeutic formulations including the calcium channel blockers verapamil and diltiazem and the beta-blocker propranolol.

The Use of Calcium Antagonists in the Therapy of Hypertension in the Elderly

Calcium antagonists (calcium channel blockers) are widely used in the treatment of hypertension and other cardiovascular diseases. The results of a large number of clinical trials have demonstrated that calcium antagonists are as efficacious as other classes of antihypertensive agents in decreasing blood pressure in the elderly patients. Large clinical trials have shown the effectiveness of calcium antagonists (with long duration of action) in reducing cardiovascular and cerebrovascular morbidity and mortality in elderly hypertensive patients. The calcium antagonists are a chemically, pharmacologically and therapeutically heterogeneous group of agents. Among themselves, they differ in vasoselectivity, effect on cardiac conduction, sympathetic activation, adverse effect profile, ability to protect against target organ damage, suitability for patients with co-morbid conditions, and pharmacodynamic characteristics. The calcium antagonists can be used as single agents or in combination with other antihypertensive drugs. These drugs should not be used as first-line drugs in treating high blood pressure in patients with heart failure, since drugs in other classes provide more benefits. The dihydropyridine calcium antagonists should not be used in post-myocardial infarction patients or in patients with unstable angina; however, non-dihydropyridines may be used in such patients. The adverse effects of dihydropyridines include peripheral and ankle edema, flushing and headache. The short-acting preparations of the older calcium antagonists are no longer used, because of the potential for adverse cardiovascular outcome.

Cardiovascular prevention and blood pressure reduction: a quantitative overview updated until 1 March 2003

BACKGROUND

In a meta-analysis published in October 2001, we reported that new and old classes of antihypertensive drugs had similar long-term efficacy and safety. Furthermore, we observed that in clinical trials in hypertensive or high-risk patients gradients in systolic pressure accounted for most differences in outcome.

OBJECTIVE

To test whether our previous conclusions would hold, we updated our quantitative overview with new information from 14 clinical trials presented before 1 March 2003.

METHODS

To compare new and old antihypertensive drugs, we computed pooled odds ratios from stratified 2 x 2 contingency tables. If Zelen's test of heterogeneity was significant, we used a random effects model. In a meta-regression analysis, we correlated odds ratios with corresponding between-group differences in systolic pressure. We then contrasted observed odds ratios with those predicted from gradients in systolic pressure.

MAIN OUTCOMES

Differences in achieved systolic blood pressure and incidence of total and cardiovascular mortality, cardiovascular events, stroke, myocardial infarction and heart failure. NEW VERSUS OLD DRUGS: In 15 trials, 120 574 hypertensive patients were randomized to old drugs (diuretics or beta-blockers) or new agents [calcium-channel blockers, alpha-blockers, angiotensin-converting enzyme (ACE) inhibitors or angiotensin type-1 receptor (AR1) blockers]. Old and new drugs provided similar protection against total and cardiovascular mortality and fatal plus non-fatal myocardial infarction. Calcium-channel blockers, including (-8%, P = 0.07) or excluding verapamil (-10%, P = 0.02), as well as AR1 blockers (-24%, P = 0.0002) resulted in better stroke prevention than did the old drugs, whereas the opposite trend was observed for ACE inhibitors (+10%, P = 0.03). The risk of heart failure was higher (P < 0.0001) on calcium-channel blockers (+33%) and alpha-blockers (+102%) than on conventional therapy involving diuretics. META-REGRESSION: Between-group differences in achieved systolic pressure ranged from 0.1 to 3.2 mmHg in seven actively controlled trials (73 237 patients), and from 2.1 to 22.1 mmHg in seven studies comparing varying intensities of blood pressure lowering (11 128 patients). For these 14 new trials, we predicted outcome from achieved systolic blood pressure using our previously published meta-regression models based on 30 trials with 149 407 patients. In general, predicted and observed odds ratios were similar. Larger reductions in systolic pressure (weighted mean 1.8 mmHg) in two trials accounted for the advantage of AR1 blockers over conventional therapy in the prevention of stroke. Only for cardiovascular mortality in very old patients (P = 0.02) and for cardiovascular events and myocardial infarction in old Australians (P < 0.05), the observed odds ratios deviated from our predictions based on the gradients in systolic blood pressure.

INTERPRETATION

The hypothesis that new antihypertensive drugs, such as calcium-channel blockers, alpha-blockers, ACE inhibitors or AR1 blockers might influence cardiovascular prognosis over and beyond their antihypertensive effects remains unproven. The finding that blood pressure differences largely accounted for cardiovascular outcome emphasizes the desirability of tight blood pressure control. However, the level to which blood pressure must be lowered to achieve maximal benefit remains currently unknown.

Drug Therapy for Hypertension: Does ALLHAT Alter our Approach?

This continuing feature will update readers on recent developments in cardiovascular pharmacotherapy. Cardiovascular disease remains the number one killer in the US, and more clinical outcome trials have been conducted in cardiology than in any other field of medicine. Given this rapidly expanding knowledge base, pharmacists can have a significant impact on prevention and treatment — if they keep current with developments in drug therapy.

Pharmacokinetics of propranolol after single and multiple dosing with sustained release propranolol or propranolol CR (innopran XL) , a new chronotherapeutic formulation

Blood pressure rises rapidly upon waking and may be responsible, in part, for the increased incidence of myocardial infarction and stroke during the morning hours. Current formulations and dosing of antihypertensive drugs do not provide maximum coverage during this vulnerable period. This study was performed to demonstrate that propranolol CR (Innopran XL), a novel chronotherapeutic formulation of propranolol designed for nighttime dosing, has appropriate pharmacokinetics to provide maximum cardioprotective effect in the morning. Pharmacokinetics of propranolol CR and sustained-release propranolol after single and multiple doses were determined in normal male volunteers in this open-label, 2-period crossover study. The drugs were dosed in the evening and serial blood samples were taken for determination of propranolol concentration the next 24 to 72 hours. After a single 160-mg dose of propranolol CR administered at 10 pm, absorption was delayed by about 4 hours, after which plasma concentration rose steadily, reaching a peak at about 10:00 am. In contrast, after dosing with sustained release propranolol, plasma levels of propranolol began to rise almost immediately, reaching a plateau between 4:00 am and 10:00 am. During multiple dosing, steady-state trough plasma concentrations were achieved after 2 days with either drug. After the final dose, the plasma profiles of both drugs were similar to those observed in the single-dose study. Bioavailability was similar for both formulations of propranolol. Propranolol CR exhibited appropriate pharmacokinetics for a chronotherapeutic approach to the treatment of hypertension.

Premature termination of clinical trials--lessons learned

Controlled clinical trials in cardiovascular disease are the cornerstone for therapeutic advances in this field of medicine. Since the introduction of the concept of controlled clinical trials there has been substantial progress in the design, conduct, and analysis of such studies. A growing awareness of ethical issues emerging from such trials has heightened public awareness, increased investigator scrutiny, and reinforced the need for interim data analysis. A benefit of such interim analyses is that either an entire clinical trial or a specific treatment limb can be stopped if the observed findings argue for premature termination. For example, highly positive findings, as were noted in the HOPE Study (Heart Outcomes Prevention Evaluation), led to its being stopped after 4.5 years of treatment, which was 1 year early. Alternatively, the doxazosin treatment limb of the ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial) and the amlodipine treatment limb of AASK (African American Study of Kidney Disease and Hypertension) were stopped early because of negative findings with each respectively. Finally, economic considerations can enter into the decision to close a study early as was the case in the CONVINCE (Controlled Onset Verapamil Investigation of Cardiovascular End Points) trial. Most such decisions rely heavily on information obtained from independent data and safety monitoring boards. Such boards ensure patient safety by providing an unbiased ongoing review of data, which would otherwise be unavailable until a study's completion. Early termination of a clinical trial can have important clinical implications and, in particular, can redirect patterns of clinical practice.

Calcium channel antagonists in the treatment of hypertension

Calcium channel antagonists are widely used antihypertensive agents. Their popularity among primary care physicians is not only due to their blood pressure-lowering effects, but also because they appear to be effective regardless of the age or ethnic background of the patients. The first available calcium channel antagonists utilized immediate-release formulations which, although effective in patients with angina pectoris, were not approved by the US FDA for use in hypertension. When long-acting once-daily formulations were approved in this indication, the short-acting preparations--which had by then become generic and inexpensive--retained some residual unapproved use for hypertension. An observational case-controlled trial, based on such usage, noted that these agents were associated with a greater risk of myocardial infarctions than conventional agents such as diuretics and beta-adrenoceptor antagonists. Further case-controlled trials showed, in fact, that the dangers of calcium channel antagonists were confined to the short-acting agents and that approved long-acting agents were at least as well tolerated and effective as other antihypertensive drugs. Cardiovascular outcomes during treatment with calcium channel antagonists have been examined in randomized, controlled trials. Compared with placebo, the calcium channel antagonists clearly prevented strokes and other cardiovascular events and reduced mortality. The effects of these agents on survival and clinical outcomes were similar to those with other antihypertensive drugs. There is a slight tendency for the calcium channel antagonists to be more effective than other drug types in preventing stroke, but slightly less effective in preventing coronary events. These observations extend to high-risk patients with hypertension including those with diabetes mellitus. Even so, patients with evidence of nephropathy should not receive monotherapy with calcium channel antagonists. Such patients are optimally treated with angiotensin receptor antagonists or ACE inhibitors, although addition of other drugs, including calcium channel antagonists, is often required to achieve the tight blood pressure control necessary to provide adequate renal protection. Calcium channel antagonists have a highly acceptable tolerability profile and careful reviews of available data have shown that their use is not associated with increased bleeding or promotion of tumor formation. It is now recognized that reduction of blood pressure in patients with hypertension to levels often <130/85 mm Hg should be undertaken in presence of other cardiovascular risk factors or evidence of end organ damage. Because of this important concept, calcium channel antagonists, like the other antihypertensive drug classes, are progressively being prescribed less often as monotherapy, but more typically as part of combination regimens.

Ongoing clinical trials in systemic hypertension

Hypertension was identified as a cardiovascular risk factor in the late fifties and still remains a public health issue. The number of patients treated reaches only half of those diagnosed and, of those treated, half fail to reach target blood pressure. Furthermore, the number of antihypertensive drugs reaching the market has increased exponentially in the last few years, however, the impact on treatment and on attaining target blood pressure levels remains to be seen. The high percentage of treated patients who do not reach target blood pressure, combined with the high number of patients requiring more than one antihypertensive drug, have triggered a series of long-term morbidity and mortality trials comparing different therapeutic approaches ('new' pharmacological classes vs. 'old' pharmacological classes). These are described in this paper.

Pharmacotherapy in congestive heart failure. Prematurely terminated clinical trials and their application to cardiovascular medicine

Controlled clinical trials in cardiovascular disease remain the cornerstone of field-specific therapeutic advances. Since the introduction of the concept of controlled clinical trials, there has been considerable fine-tuning of the design, conduct, and analysis of such studies. A growing awareness of ethical issues emerging from such trials has led to increased public and investigator scrutiny and the routine requirement for both interim data analysis and full conflict-of-interest disclosure. A benefit of such interim analyses is that either an entire clinical trial or a specific treatment limb can be stopped if the observed findings warrant early termination. For example, highly positive findings, as were noted in the HOPE Study (Heart Outcomes Prevention Evaluation), led to its closure after 4.5 years of treatment, which was 1 year earlier than anticipated. Also, the doxazosin treatment limb of ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial) and the amlodipine treatment limb of AASK (African American Study of Kidney Disease and Hypertension) were stopped early, because of negative findings in one of their treatment limbs. Finally, economic considerations can enter into the decision to close a study early, as was the case in the CONVINCE (Controlled-Onset Verapamil Investigation of Cardiovascular Endpoints) trial. Most such decisions rely heavily on information obtained from independent data and safety monitoring boards. Such boards ensure patient safety by providing an unbiased, ongoing review of data, which would otherwise be unavailable until a study's completion. Early termination of a clinical trial can have important clinical and economic implications and, in particular, can substantially redirect the pattern of clinical practice. (c)2001 CHF, Inc.

Lessons learned from prematurely terminated clinical trials

Controlled clinical trials in cardiovascular disease are the cornerstone for therapeutic advances in this field of medicine. Since the introduction of the concept of controlled clinical trials, there has been substantial progress in the design, conduct, and analysis of such studies. A growing awareness of ethical issues emerging from such trials has led to increased public and investigator scrutiny, and the routine requirement for interim data analysis. A benefit of such interim analysis is that either an entire clinical trial or a specific treatment limb can be stopped if the observed findings warrant premature termination. For example, highly positive findings, as were noted in the Heart Outcomes Prevention Evaluation (HOPE) study, led to its closure about 1 year early after 4.5 years of treatment. Alternatively, the doxazosin treatment limb of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) and the amlodipine treatment limb of the African-American Study of Kidney Disease and Hypertension (AASK) were stopped early because of negative findings. Finally, economic considerations can enter into the decision to close a study early as was the case in the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) trial. Most such decisions rely heavily on information obtained from independent data and safety monitoring boards. Such boards ensure patient safety by providing an unbiased ongoing review of data, which would otherwise be unavailable until a study's completion. Early termination of a clinical trial can have important clinical implications and, in particular, can redirect patterns of clinical practice.

Timing treatment to the rhythm of disease. A short course in chronotherapeutics

The recognition of circadian rhythms in both normal human biologic function and disease has heightened the awareness that the timing of drug regimens may have an important impact on effectiveness of treatment. Outcomes in several diseases that have predictable circadian variations (e.g., arthritis, asthma, allergies, pepticulcer disease, dyslipidemia, cancer) have been improved by matching the timing of medication use to the circadian rhythm of the illness. Results of the ongoing CONVINCE study may provide evidence that chronotherapy for hypertension and angina pectoris may be more effective than traditional homeostatic treatment.

Circadian rhythm of double (rate-pressure) product in healthy normotensive young subjects

The double product (DP), systolic blood pressure multiplied by heart rate, is a surrogate measure of myocardial oxygen demand and cardiac workload used increasingly today in medicine. The double product is more strongly correlated with left ventricular mass than the daily blood pressure mean. The purpose of this study was to describe the normative circadian pattern of the double product in healthy normotensive young adults. We studied 125 men and 75 women, 23.0+/-3.3 (mean +/- SD) years of age, without medical history of hypertension and 24h ambulatory systolic/diastolic blood pressure mean consistently below 135/85 mm Hg. Subjects underwent ambulatory blood pressure monitoring at 30-minute intervals for 48 consecutive hours once each season of the year, yielding 930 protocol-correct blood pressure and heart rate time series. Subjects maintained their usual routine of diurnal activity and nocturnal sleep and avoided use of over-the-counter and other medication. Circadian rhythmicity in the double product was established by population multiple-component analysis. The double product rose rapidly from the lowest value, attained 3h before awaking from sleep at night, to a markedly elevated level at the commencement of morning activity. The double product was highest in the afternoon, roughly 7h after the commencement of diurnal activity. In both men and women, the shape of the high-amplitude circadian rhythm in the double product was best described by a complex model composed of three cosine curves having periods of 24h, 12h, and 6h. The 24h mean in the double product of 8092.51+/-42.76 (mean +/- SD) in men was significantly lower than that of 8353.17+/-37.48 in women (P < .001). The circadian double amplitude of the rhythm was statistically significantly greater (P < .001) in men (50% of the 24h mean) than women (44% of the 24h mean). The double product did not differ between seasons in women, but it did in men (P = .017) due to reduced heart rate in summer. The circadian pattern of large amplitude in the double product and its gender differences must be taken into account when using this variable to assess cardiac workload, risk of left ventricular hypertrophy, and efficiency of antihypertensive therapy.

Cardiovascular risk and therapeutic intervention for the early morning surge in blood pressure and heart rate

The incidence of most adverse cardiovascular events appears to follow a circadian pattern, reaching a peak in the morning shortly after wakening and arising. The activities of many physiologic parameters, including hemodynamic, hematologic and humoral factors, also fluctuate in a cyclical manner over the 24h. It has been suggested that, during the post-awakening hours, the phases of these cycles synchronize to create an environment that predisposes to atherosclerotic plaque rupture and thrombosis in susceptible individuals, thereby accounting for the heightened cardiovascular risk at this time of day. Blood pressure and heart rate are part of this physiologic process, following a clear circadian rhythm characterized by a fall during sleep and a sharp rise upon awakening. This so-called 'morning surge' in blood pressure may act as a trigger for cardiovascular events, including myocardial infarction and stroke. The clinical implication of these observations is that antihypertensive therapy should provide blood pressure control over the entire interval between doses. For agents taken once daily in the morning, the time of trough plasma drug level (and lowest pharmacodynamic effect) will often coincide with the early morning surge in blood pressure and heart rate. For these reasons, chronotherapeutic formulations of drugs and intrinsically long-acting antihypertensive agents provide the most logical approach to the treatment of hypertensive patients since they provide 24 h blood pressure control from a single daily dose as well as attenuating the early morning rise in blood pressure (and in some instances heart rate).

Baseline Characteristics and Early Blood Pressure Control in the CONVINCE Trial

-Blood pressure (BP) control rates around the world are suboptimal. Part 2 of the National Health and Nutrition Educational Survey (NHANES) III indicates that only 27.4% of hypertensive Americans aged 18 to 74 years have a BP of <140/90 mm Hg. We wanted to assess BP control during the first 2 years and to describe the baseline characteristics of patients enrolled in the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) Study, an international clinical trial that compares outcomes in hypertensive patients randomized to initial treatment with either controlled-onset extended-release verapamil or the investigator's choice of atenolol or hydrochlorothiazide. At randomization, BP was <140/90 mm Hg in only 20.3% of the 16 602 subjects (average+/-SD age 65.6+/-7.4 years; 56% women, 84% white/7% black/7% Hispanic). The average BP at enrollment was 148/85 mm Hg for patients taking BP medications (n=13 879) and 161/94 mm Hg for previously untreated patients (n=2723). After medication titration, with a transtelephonic computer that recommended an increase in the dose or number of antihypertensive agents whenever the BP was 140/90 mm Hg, 84.8% of the subjects attained the goal BP. During 2 years of treatment, BP control was maintained in 67% to 69% of the subjects (69% to 71% for systolic BP of <140 mm Hg and 90% for diastolic BP of <90 mm Hg). These data suggest that the control of systolic BP is more difficult than the control of diastolic BP. The US national goal of having 50% of hypertensives with a BP of <140/90 mm Hg may be achievable if a forced titration strategy is used. Interested investigators, free care and medications, and well-educated subjects may make the attainment of such a goal easier in the CONVINCE study than in the general population.

Verapamil revisited: a transition in novel drug delivery systems and outcomes

Verapamil, the oldest calcium-channel blocker, is now being rediscovered and reevaluated in the light of new novel drug delivery systems and new evidence-based trials. Verapamil, a phenylalkylamine, is useful in the treatment of hypertension, stable angina, and narrow QRS supraventricular arrhythmias. This calcium antagonist is effective in both young and old, and both black and white hypertensive patients, and is free of metabolic side effects. Verapamil has a well-documented history as an effective antianginal agent when directly compared with a beta-blocker, and is more effective in reducing myocardial ischemia compared with amlodipine monotherapy. Because of the short half-life of verapamil, drug delivery systems are used to prolong the duration of action. Novel drug delivery systems using encapsulated beads or a modified osmotic pump have been designed to be taken at nighttime to provide maximal blood pressure reduction in the early morning hours and effective 24-hour blood pressure control, and to avoid excessive blood pressure reduction during sleep. The Verapamil in Hypertension and Atherosclerosis Study has documented equivalent effectiveness of verapamil compared with chlorthalidone, but showed superior plaque regression and reduced events in subjects with the greatest plaques with verapamil treatment. The Angina Prognosis Study in Stockholm, comparing verapamil and metoprolol for stable angina, found no difference in total cardiovascular mortality or combined cardiovascular events. Other large ongoing randomized, multicenter trials, including Controlled-Onset Verapamil Investigation of Cardiovascular Endpoints and the International Verapamil-Trandolapril Study, will expand our knowledge of the role of verapamil in the treatment of hypertension.

Health outcomes associated with calcium antagonists compared with other first-line antihypertensive therapies: a meta-analysis of randomised controlled trials

BACKGROUND

Several observational studies and individual randomised trials in hypertension have suggested that, compared with other drugs, calcium antagonists may be associated with a higher risk of coronary events, despite similar blood-pressure control. The aim of this meta-analysis was to compare the effects of calcium antagonists and other antihypertensive drugs on major cardiovascular events.

METHODS

We undertook a meta-analysis of trials in hypertension that assessed cardiovascular events and included at least 100 patients, who were randomly assigned intermediate-acting or long-acting calcium antagonists or other antihypertensive drugs and who were followed up for at least 2 years.

FINDINGS

The nine eligible trials included 27,743 participants. Calcium antagonists and other drugs achieved similar control of both systolic and diastolic blood pressure. Compared with patients assigned diuretics, beta-blockers, angiotensin-converting-enzyme inhibitors, or clonidine (n=15,044), those assigned calcium antagonists (n=12,699) had a significantly higher risk of acute myocardial infarction (odds ratio 1.26 [95% CI 1.11-1.43], p=0.0003), congestive heart failure (1.25 [1.07-1.46], p=0.005), and major cardiovascular events (1.10 [1.02-1.18], p=0.018). The treatment differences were within the play of chance for the outcomes of stroke (0.90 [0.80-1.02], p=0.10) and all-cause mortality (1.03 [0.94-1.13], p=0.54).

INTERPRETATION

In randomised controlled trials, the large available database suggests that calcium antagonists are inferior to other types of antihypertensive drugs as first-line agents in reducing the risks of several major complications of hypertension. On the basis of these data, the longer-acting calcium antagonists cannot be recommended as first-line therapy for hypertension.

Ethnic differences in nocturnal blood pressure decline in treated hypertensives

Lack of a nocturnal decline in blood pressure (BP) has been associated with more severe end organ damage in hypertensives, and blacks appear less likely than whites to have a > 10% drop in nighttime BP ("dipping"). Little information is available about the relationship between treatment regimens, ethnic group classification, and dipping in treated hypertensive patient populations. We obtained 24-h ambulatory BP readings in 438 adult white (n = 103), black (n = 200) and Hispanic (n = 135) treated hypertensives. Tycos monitors were connected in patients' homes before their usual morning medication dose time. Research assistants administered a quality-of-life questionnaire, recorded patients' drug regimen, and observed the patients take their morning dose. Monitors were programmed to record BP every 30 min. Dippers were defined as persons who had a drop of > or = 10% decline in average daytime (08:00 to 22:00) compared to nighttime (00:00 to 04:00) BP. Logistic regression modeling was used to assess the relationship between demographic and treatment variables and probability of dipping. Twenty-four-hour average BP was similar in all three ethnic groups. However, the absence of a systolic dip was significantly more common in black and Hispanic men than in white men (OR black v white = 11.54, 95% CI = 3.92 to 34.01; OR Hispanic v white = 7.32, 95% CI = 2.47 to 21.68). There were no ethnic group differences in probability of systolic dipping among women. Absence of a diastolic dip was approximately twice as common in blacks and Hispanics than in whites, with no marked gender-by-ethnic-group interaction in the magnitude of the association. Of the 10 most commonly prescribed antihypertensives, no single drug was positively associated with nocturnal BP decline. Later versus earlier morning dose time, but not once-a-day dosing, was associated with absence of dipping. Treated black and Hispanic hypertensives are less likely to "dip" than non-Hispanic whites. No particular drug was positively associated with dipping.

Failure of magnesium to protect isolated cardiomyocytes from effects of hypoxia or metabolic poisoning

BACKGROUND

MgSO4 appears to reduce infarct size in animal models of myocardial infarction-reperfusion, but only if given before reperfusion. The mechanisms underlying this effect have not been established, nor has the discrepancy between these results and the lack of efficacy in the Fourth International Study of Infarct Survival (ISIS-4) been explained.

HYPOTHESIS

The study was undertaken to examine the hypothesis that Mg2+ protects myocardium threatened by ischemia.

METHODS

We studied the effects of extracellular magnesium [Mg2+](e) at 0.6 and 1.8 mmol/l on isolated myocytes exposed to 2.5 mmol/l NaCN + 5 mmol/l 2-deoxyglucose or to profound hypoxia.

RESULTS

Nonpaced cells shortened at a mean of 8.8 min after onset of metabolic inhibition in [Mg2+](e) = 1.8 mmol/l, 9.6 min in [Mg2+](e) = 0.6 mmol/l (not significant). Paced cells shortened after 9.5 min in [Mg2+](e) = 1.8 mmol/l, 10.2 min at [Mg2+](e) = 0.6 mmol/l. On washout of inhibitors, 93% of cells underwent hypercontracture at [Mg2+](e) = 1.8 mmol/l, 94.8% at [Mg2+](e) = 0.6 mmol/l. During hypoxia, nonpaced cells in [Mg2+](e) = 1.8 mmol/l shortened after 67 +/- 11 min compared with 62.5 +/- 28 min at [Mg2+](e) = 0.6 mmol/l. Paced cells shortened after 25.8 +/- 12.9 min at [Mg2+](e) = 1.8 mmol/l and after 28.7 +/- 13.6 min at [Mg2+]e = 0.6 mmol/l. Although there was a trend toward longer survival at higher [Mg2+](e), the difference was small and not significant (p > 0.05, Student's paired t-test).

CONCLUSION

We find no evidence to support the hypothesis that [Mg2+] protects myocardium threatened by ischemia. This is consistent with clinical data but contradicts data from animal experiments.

Large multicentre hypertension trials

The earlier large multicentre trials in hypertensive patients addressed questions of whether mild to moderate hypertension should be treated and whether similar approaches would be effective in elderly hypertensive patients or those with isolated systolic hypertension. The research focus of recent trials has now shifted to how rather than whether such patients should be treated. Trials such as the Hypertension Optimal Treatment study attempted to discern optimal targets for long-term blood pressure control. Although unsuccessful in this primary aim, they have established the safety of aggressive blood pressure lowering to diastolic targets of less than 80 mmHg as well as the safety and efficacy of a calcium entry blocker as a first line antihypertensive approach. The Captopril Prevention Project study and Swedish Trial in Old Patients with Hypertension-2 trial focussed on whether there might be specific antiatherosclerotic advantages of the newer agents (angiotensin converting enzyme inhibitors and calcium entry blockers) over conventional therapy in comparison studies with beta blockers and diuretics. Similar efficacy for cardiovascular outcomes appears to be emerging for each of the major classes of drugs with the degree of blood pressure lowering of prime importance in cardiovascular disease prevention.

Renal artery stenosis as a cause of renal impairment: implications for treatment of hypertension and congestive heart failure

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Chronotherapeutics: are there meaningful differences among antihypertensive drugs?

In the past decade, many publications have dealt with the possible relationship between biological rhythms and the incidence of cardiovascular events. A high proportion of treated hypertensive patients have cardiovascular complications, and chronotherapy, which permits the use of drugs that are maximally effective at different points in the circadian cycle, may be an interesting and valuable approach to decreasing morbidity and mortality in these patients. This article summarizes current knowledge on the new science of chronopharmacology, as demonstrated in several clinical studies that have used conventional agents administered at various points in the circadian cycle as well as new chronotherapeutic agents, such as controlled onset extended release (COER)-verapamil. In addition, emphasis is given to a rigorous evaluation of antihypertensive agents in terms of efficacy and duration of effect to obtain adequate and sustained lowering of blood pressure over the 24-hour period.

Chronopharmacology and chronotherapy of cardiovascular medications: relevance to prevention and treatment of coronary heart disease

Biological functions and processes, including cardiovascular ones, exhibit significant circadian (24-hour) and other period rhythms. Ambulatory blood pressure assessment reveals marked circadian rhythms in blood pressure both in normotensive persons and hypertensive patients, whereas Holter monitoring substantiates day-night patterns in electrocardiographic events of patients with ischemic heart disease. The concept of homeostasis, that is, constancy of the milieu interne, which has dominated the teaching, research, and practice of medicine during the 20th century,is now being challenged by emerging concepts from the field of chronobiology-the science of biological rhythms. Epidemiologic studies document the heightened morning-time risk of angina, myocardial infarction, and stroke. Circadian rhythms in coronary tone and reactivity, plasma volume, blood pressure, heart rate, myocardial oxygen demand, blood coagulation, and neuroendocrine function plus day-night patterns in the nature and strength of environmental triggers all contribute to this morning vulnerability. Homeostatically devised pharmacotherapies, that is, medications formulated to ensure a near-constant drug concentration, may not be optimal to adequately control diseases that vary in risk and severity during the 24 hours. Moreover, circadian rhythms in the physiology of the gastrointestinal tract, vital organs, and body tissues may give rise to administration-time differences in the pharmacokinetics and effects of therapies. Thus the same medication consumed in the same dose under identical conditions in the evening and morning may not exhibit comparable pharmacokinetics and dynamics. New technology makes possible chronotherapy, that is, increase of the efficiency and safety of medications by proportioning their concentrations during the 24 hours in synchrony with biological rhythm determinants of disease. The chronotherapy of peptic ulcer disease achieved by the evening dosing of H 2-receptor antagonists and of asthma by the evening dosing of special drug delivery forms of theophylline and morning methylprednisolone administration has proven to be beneficial. Controlled-onset extended-release verapamil constitutes the first chronotherapy of essential hypertension and ischemic heart disease; once-a-day bedtime dosing results in a high drug concentration in the morning and afternoon and a reduced one overnight. Studies demonstrate effective 24-hour control of blood pressure, including the attenuation of its rapid rise in the morning, without induction of nighttime hypotension. Moreover, this formulation effectively controls angina, especially in the morning when the risk of ischemia is greatest. Determination of the role of verapamil chronotherapy in the primary prevention of cardiovascular morbidity and mortality awaits the results of the CONVINCE trial now in progress.