Characteristics of participants at baseline in the Treatment of Mild Hypertension Study (TOMHS)

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 We also contacted the authors of relevant papers regarding further published and unpublished work and checked the references of published studies to identify additional trials.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.

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.

Comparison of five antihypertensive monotherapies and placebo for change in left ventricular mass in patients receiving nutritional-hygienic therapy in the Treatment of Mild Hypertension Study (TOMHS)

BACKGROUND

Increased left ventricular mass (LVM) by echocardiography is associated with increased risk of cardiovascular disease. Thus, it is of interest to compare the effects of both pharmacological and nonpharmacological approaches to the treatment of hypertension on reduction of LVM.

METHODS AND RESULTS

Changes in LV structure were assessed by M-mode echocardiograms in a double-blind, placebo-controlled clinical trial of 844 mild hypertensive participants randomized to nutritional-hygienic (NH) intervention plus placebo or NH plus one of five classes of antihypertensive agents: (1) diuretic (chlorthalidone), (2) beta-blocker (acebutolol), (3) alpha-antagonist (doxazosin mesylate), (4) calcium antagonist (amlodipine maleate), or (5) angiotensin-converting enzyme inhibitor (enalapril maleate). Echocardiograms were performed at baseline, at 3 months, and annually for 4 years. Changes in blood pressure averaged 16/12 mm Hg in the active treatment groups and 9/9 mm Hg in the NH only group. All groups showed significant decreases (10% to 15%) in LVM from baseline that appeared at 3 months and continued for 48 months. The chlorthalidone group experienced the greatest decrease at each follow-up visit (average decrease, 34 g), although the differences from other groups were modest (average decrease among 5 other groups, 24 to 27 g). Participants randomized to NH intervention only had mean changes in LVM similar to those in the participants randomized to NH intervention plus pharmacological treatment. The greatest difference between groups was seen at 12 months, with mean decreases ranging from 35 g (chlorthalidone group) to 17 g (acebutolol group) (P = .001 comparing all groups). Within-group analysis showed that changes in weight, urinary sodium excretion, and systolic BP were moderately correlated with changes in LVM, being statistically significant in most analyses.

CONCLUSIONS

NH intervention with emphasis on weight loss and reduction of dietary sodium is as effective as NH intervention plus pharmacological treatment in reducing echocardiographically determined LVM, despite a smaller decrease in blood pressure in the NH intervention only group. A possible exception is that the addition of diuretic (chlorthalidone) may have a modest additional effect on reducing LVM.

Ethnicity and renal disease: lessons from the Multiple Risk Factor Intervention Trial and the Treatment of Mild Hypertension Study

Hypertension, particularly severe hypertension, has proven to be a risk factor for renal disease. Whether the relationship of blood pressure (BP) and high renal disease exists across a wide range of BP levels has been less clear. Compared with whites, blacks have a higher rate of end-stage renal disease from a multiplicity of causes, including hypertension, most prominently in younger age groups. To examine ethnic patterns of renal disease across BPs spanning the range of "normal" to "elevated," data were summarized from three large studies: (1) 12-year mortality for the 347,978 men (22,471 black and 325,507 white) without prior myocardia infarction (MI) screened for the Multiple Risk Factor Intervention Trial (MRFIT) who have been followed an average of 12 years for cause-specific mortality, (2) the baseline and 6-year change in renal function in 5,524 hypertensive men (463 black and 5,061 white) randomized in the MRFIT, and (3) the baseline and 1-year change in creatinine level are compared in 902 black and white men and women (177 black and 725 white) with mild hypertension in the Treatment of Mild Hypertension Study (TOMHS). In the MRFIT screenees, there was a monotonic increase in the risk of renal mortality at higher BP levels, even within the "normal range," both in black and white men. Blacks had higher baseline creatinine levels in both the MRFIT and TOMHS. In the MRFIT hypertensive patients, 6-year change in creatinine predicts coronary heart disease and all-cause mortality while the baseline creatinine level did not. Comparisons of randomized groups in the MRFIT or TOMHS did not demonstrate improved renal function with more aggressive BP lowering, but in MRFIT average on-treatment DBP < 95 mm Hg was associated with more favorable slopes of reciprocal creatinine. At 1 year, no gender-specific ethnic differences in creatinine change were observed in TOMHS. In the MRFIT hypertensive men, 6-year creatinine change was slightly more favorable in white men than in black men (-0.088 mumol/l v +3.09 mumol/L, P = 0.004). These data demonstrate (1) a graded and continuous relationship between BP and renal disease in blacks and whites across a wide BP range, (2) that creatinine change predicts subsequent mortality, at least in hypertensive men treated with diuretic-based pharmacologic regimen, and (3) possibly different pattern of creatinine change in response to antihypertensive drug therapy in blacks and whites.