Combination therapy in hypertension

The goal of antihypertensive therapy is to abolish the risks associated with blood pressure (BP) elevation without adversely affecting quality of life. Drug selection is based on efficacy in lowering BP and in reducing cardiovascular (CV) end points, including stroke, myocardial infarction, and heart failure. Although the choice of initial drug therapy exerts some effect on long-term outcomes, it is evident that BP reduction per se is the primary determinant of CV risk reduction. Available data suggest that at least 75% of patients will require combination therapy to achieve contemporary BP targets, and increasing emphasis is being placed on the practical tasks involved in consistently achieving and maintaining goal BP in clinical practice. It is within this context that the American Society of Hypertension presents this Position Paper on Combination Therapy for Hypertension. It will address the scientific basis of combination therapy, present the pharmacologic rationale for choosing specific drug combinations, and review patient selection criteria for initial and secondary use. The advantages and disadvantages of single-pill (fixed) drug combinations and the implications of recent clinical trials involving specific combination strategies will also be discussed.

Combination therapy versus monotherapy as initial treatment for stage 2 hypertension: a prespecified subgroup analysis of a community-based, randomized, open-label trial

BACKGROUND

Current guidelines suggest consideration of initial combination therapy for patients with stage 2 hypertension, but rates of hypertension treatment and control in clinical practice vary according to age, race, sex, and body mass index (BMI).

OBJECTIVE

This was a prespecified subgroup analysis of one of the primary efficacy end points-mean change in systolic blood pressure (SBP) at 6 weeks -in a previously published community-based, randomized, open-label trial comparing valsartan monotherapy with valsartan/hydrochlorothiazide (HCTZ) combination therapy as initial treatment for high-risk patients with stage 2 hypertension.

METHODS

Eligible participants with stage 2 hypertension (SBP >or=160 mm Hg and/or diastolic blood pressure [DBP] >or=100 mm Hg) were treated with valsartan 160 mg/d or valsartan/HCTZ 160/12.5 mg/d for 2 weeks, followed by forced titration to valsartan 320 mg/d or valsartan/HCTZ 320/12.5 mg/d for an additional 4 weeks. In addition to the primary blood pressure end point (change in SBP at 6 weeks), secondary blood pressure end points at 6 weeks included changes in DBP and the proportion of patients achieving a blood pressure control threshold of <140/90 mm Hg (<130/80 mm Hg for patients with diabetes), as recommended by the Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7). The subgroups of interest were women, blacks, Hispanics, the elderly (age >or=65 years), patients with diabetes, smokers, and lean, overweight, and obese subjects (BMI <25, 25-<30, and =30 kg/m(2), respectively).

RESULTS

The randomized trial included 1668 patients (756 [45.3%] female, 392 [23.5%] black, 109 [6.5%] Hispanic, 220 [13.2%] elderly, 970 of 1641 [59.1%] obese, 166 [10.0%] with diabetes, 467 [28.0%] smokers) with stage 2 hypertension. Among those allocated to combination therapy compared with monotherapy, the mean (SD) change in SBP at 6 weeks was -27.4 (18.5) and -19.3 (17.7) mm Hg in women, -21.4 (17.6) and -12.6 (18.5) mm Hg in black subjects, -21.7 (17.6) and -16.3 (16.5) mm Hg in Hispanic subjects, -25.5 (20.2) and -16.9 (17.9) mm Hg in the elderly, and -23.6 (18.1) and -15.9 (16.2) mm Hg in obese subjects. With the exception of the results for Hispanics, all comparisons of combination therapy and monotherapy were statistically significant (P<or=0.01). A higher proportion of those receiving valsartan/ HCTZ compared with valsartan monotherapy reached the JNC 7-defined blood pressure goal (44.5% vs 29.1%, respectively; P<0.001). This pattern was seen consistently in most subgroups analyzed, including men (41.8% vs 27.9%; P<0.001), women (47.8% vs 30.5%; P<0.001), white subjects (46.4% vs 33.8%; P<0.001), black subjects (41.8% vs 19.1%; P<0.001), those aged <65 years (44.6% vs 29.7%; P<0.001), those aged >or=65 years (43.9% vs 24.5%; P=0.004), overweight subjects (49.0% vs 31.2%; P<0.001), and obese subjects (41.4% vs 26.0%; P<0.001). In the entire study cohort, patients assigned to combination therapy had a significantly higher incidence of dizziness compared with those assigned to monotherapy (8.5% vs 4.7%; P=0.002); however, there was no statistically significant difference in the frequency of adverse events between treatment groups in the prespecified subgroups.

CONCLUSIONS

Across various subgroups of patients with stage 2 hypertension, combination therapy was consistently associated with a significantly greater reduction in SBP than monotherapy. With the exception of a significantly greater increase in dizziness compared with monotherapy, combination therapy was well tolerated.

Risk-based classification of hypertension and the role of combination therapy

The recognition of a continuous relationship between elevated blood pressure (BP) and cardiovascular risk has influenced national and international guidelines for the classification, prevention, and management of hypertension. The most recent report (2003) of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure uses BP thresholds to define categories of normal, prehypertension, and hypertension. A new definition proposed by the Hypertension Writing Group in 2005 offers an approach to diagnosis and management based on global or total risk. Thus, even in the absence of sustained elevations in BP, patients may have a moderate to high risk of vascular events due to the presence of additional cardiovascular risk factors, disease markers, and target organ damage. The 2007 European guidelines continue to classify hypertension based on cutoffs while also placing emphasis on multivariate formulations for cardiovascular risk assessment and goals of therapy. All 3 sets of guidelines acknowledge the necessity of using > or =2 antihypertensive agents to attain BP goals in many patients.

Hypertension‐Related Morbidity and Mortality in African Americans—Why We Need to Do Better

Almost one third of adults in the United States have hypertension. Prevalence data among different racial or ethnic groups indicate that a disproportionate number of African Americans have hypertension compared with non-Hispanic whites and Mexican Americans. Earlier onset of high blood pressure and greater severity of hypertension contribute to a greater burden of hypertensive target organ damage in African Americans and may be a factor in the shorter life expectancy of this population compared with white Americans. There is a clear need for improved management of hypertension in African Americans via therapeutic lifestyle interventions and pharmacotherapy. While there is some evidence that particular antihypertensive agent classes provide blood pressure-lowering advantages over others, there is no support for withholding agents of any one class. When given as monotherapy, diuretics and calcium channel blockers may be relatively more effective in lowering blood pressure in African Americans than beta blockers, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers. However, when combined with a diuretic, African Americans respond as well to these agents as other racial groups. Combination therapy using antihypertensive agents with differing modes of action provides additive antihypertensive efficacy and is well tolerated. Recent guidelines recommend combination therapy as the standard of care for patients with significant blood pressure elevation, especially those with diabetes mellitus and renal disease. These comorbidities are more common in African Americans and indicate the potential need for initial therapy with more than one agent or a combination of agents in one pill.

Innovation in personalized medicine: BiDil® as a case study for integrating clinical and policy developments

BiDil^® (hydralazine and isosorbide dinitrate) represents an interesting application of personalized medicine - the first pharmaceutical specifically approved by a regulatory agency, the US FDA, for an indication in a particular population based on race as a surrogate phenotypic marker, without a companion genomic diagnostic directed at measuring drug responsiveness. The focus of this paper is to use BiDil as a case study of a personalized medicine application and evaluate its clinical and policy-relevant characteristics as an illustrative example of the usefulness of the Evaluation Data for Assessing Personalized Medicine Translation (EDAPT) evidence base.

Hypertension Treatment Guidelines: Practical Implications

The focus of blood pressure (BP) lowering is to prevent or reduce the risk for cardiovascular and renal events. This rationale forms the basis for the recent guideline statements issued by the Seventh Joint National Committee, the American Diabetes Association, the European Society of Hypertension, and the Kidney Disease Outcomes Quality Initiative. The goal BP in the majority of hypertensive patients should be less than 140/90 mm Hg, with a lower goal of less than 130/80 mm Hg in patients with diabetes or kidney disease. Meta-analyses of clinical trials with renal end points make it clear that the presence of 1 gram or more of proteinuria mandates a BP approaching 115 mm Hg to slow the progression of advanced nephropathy adequately. Compelling indications also exist for the use of certain antihypertensive agents in the setting of kidney dysfunction, diabetes, heart failure, and coronary artery disease. Initiation with 2 antihypertensive agents should be considered strongly for patients with a BP of more than 20 mm Hg greater than the systolic BP goal. This means that those with a goal BP of less than 130 mm Hg should be started on 2 antihypertensive medications with complementary actions when the systolic BP is 150 mm Hg or greater. In patients with kidney disease, reaching the BP goal requires multiple agents that should include an appropriate diuretic and an agent that blocks the renin-angiotensin-aldosterone system to slow the progression of kidney disease.

Managing hypertension in African-American patients

Epidemiologic evidence indicates that African Americans are at greater risk for hypertension compared with other ethnic groups in the United States. The prevalence of hypertension is estimated to be approximately 37% for this group, compared with 20%-25% for non-Hispanic whites. Hypertension seems to follow a more malignant course in African Americans, possibly as a result of the higher prevalence of concomitant cardiovascular risk factors in this population. Compared with white persons with hypertension, these patients are at increased risk for left ventricular hypertrophy, heart failure, and end-stage renal disease. Data suggest that ethnicity may influence the response to certain types of antihypertensive medication. Additional data indicate that more aggressive use of combination therapy may improve clinical outcomes among high-risk hypertensive patients. Based on these findings, recommendations are made for the optimal clinical management of hypertension in African-American patients.

Blockade of the renin-angiotensin system in African Americans with hypertension and cardiovascular disease

There is overwhelming evidence that the renin-angiotensin system plays a significant role in the pathophysiology of hypertension and target organ damage. Agents that regulate the renin-angiotensin system, such as angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, and aldosterone antagonists, are not only effective antihypertensive agents but can prevent target organ damage. Although diuretics remain the agents of first choice for the treatment of hypertension in African Americans, ACE inhibitors have a clear role in the management of these patients. ACE inhibitors (usually when used with a diuretic) have been shown to reduce morbidity and mortality in a wide range of patient groups. ACE inhibitors are infrequently used in African Americans because of a belief that these agents are ineffective in this racial group; however, when adequate dosing and appropriate combinations are used, ACE inhibitor therapy provides effective blood pressure control. In particular, the addition of diuretics to ACE inhibitor therapy ameliorates the racial differences in efficacy seen when ACE inhibitors are administered as monotherapy. Although further confirmation in additional clinical trials is required, increased use of these agents in African Americans will likely result in a reduction in target organ damage.

Coronary benefits of calcium antagonist therapy for patients with hypertension

Calcium antagonists effective in lowering blood pressure are a heterogeneous group including three main classes: phenylalkylamines, benzothiazepines and dihydropyridines. Dihydropyridines have a dual mode of action upon the endothelium contributing to their beneficial antihypertensive effects: (1) direct relaxation by inhibition of smooth muscle L-type calcium current, and (2) indirect relaxation through release of nitric oxide from the vascular endothelium. Calcium antagonists may affect many calcium-dependent events in the formation of atherosclerosis such as the localized accumulation of collagen, elastin, and calcium together with monocyte infiltration and smooth muscle proliferation and migration. In the INSIGHT calcification study, the overall treatment effect of nifedipine demonstrated significant inhibition of coronary calcium progression over a three-year period. Calcium antagonists improve symptoms and reduce ischemia in hypertensive patients with ischemic heart disease. Although in placebo-controlled trials calcium antagonists demonstrated a significant reduction in cardiovascular morbidity and mortality, they may be less effective than other types of antihypertensive drugs in preventing ischemic heart disease.

Lesser response to angiotensin-converting-enzyme inhibitor therapy in black as compared with white patients with left ventricular dysfunction

BACKGROUND

Black patients with heart failure have a poorer prognosis than white patients, a difference that has not been adequately explained. Whether racial differences in the response to drug treatment contribute to differences in outcome is unclear. To address this issue, we pooled and analyzed data from the Studies of Left Ventricular Dysfunction (SOLVD) prevention and treatment trials, two large, randomized trials comparing enalapril with placebo in patients with left ventricular dysfunction.

METHODS

We used a matched-cohort design in which up to four white patients were matched with each black patient according to trial, treatment assignment, sex, left ventricular ejection fraction, and age. A total of 1196 white patients (580 from the prevention trial and 616 from the treatment trial) were matched with 800 black patients (404 from the prevention trial and 396 from the treatment trial). The average duration of follow-up was 35 months in the prevention trial and 33 months in the treatment trial.

RESULTS

The black patients and the matched white patients had similar demographic and clinical characteristics, but the black patients had higher rates of death from any cause (12.2 vs. 9.7 per 100 person-years) and of hospitalization for heart failure (13.2 vs. 7.7 per 100 person-years). Despite similar doses of drug in the two groups, enalapril therapy, as compared with placebo, was associated with a 44 percent reduction (95 percent confidence interval, 27 to 57 percent) in the risk of hospitalization for heart failure among the white patients (P<0.001) but with no significant reduction among black patients (P=0.74). At one year, enalapril therapy was associated with significant reductions from base line in systolic blood pressure (by a mean [+/-SD] of 5.0+/-17.1 mm Hg) and diastolic blood pressure (3.6+/-10.6 mm Hg) among the white patients, but not among the black patients. No significant change in the risk of death was observed in association with enalapril therapy in either group.

CONCLUSIONS

Enalapril therapy is associated with a significant reduction in the risk of hospitalization for heart failure among white patients with left ventricular dysfunction, but not among similar black patients. This finding underscores the need for additional research on the efficacy of therapies for heart failure in black patients.

Racial differences in response to therapy for heart failure: analysis of the vasodilator-heart failure trials. Vasodilator-Heart Failure Trial Study Group

BACKGROUND

Heart failure in blacks has been associated with a poorer prognosis than in whites. In such diseases as hypertension, blacks show pathophysiological differences and respond differently to some therapies than whites. The aim of this study is to evaluate the clinical characteristics and response to therapy of black compared with white patients with heart failure.

METHODS AND RESULTS

In the first Vasodilator-Heart Failure Trial (V-HeFT I), 180 black male patients were compared with 450 white male patients for baseline characteristics, prognosis, and response to therapy. In V-HeFT II, the same comparisons were made for 215 black and 574 white male patients, including an analysis stratified by the presence or absence of a history of hypertension. In both trials, black patients had a lower incidence of coronary artery disease, greater incidence of previous hypertension, and a greater cardiothoracic ratio (P < .05) than white patients. In V-HeFT II, plasma norepinephrine levels were significantly less in blacks; plasma renin activity was less only in blacks with a history of hypertension. Overall mortality or hospitalization for congestive heart failure did not differ between blacks and whites in the placebo group in V-HeFT I. However, the mortality of black patients receiving hydralazine plus isosorbide dinitrate (H-I) was reduced (P = .04) in V-HeFT I, whereas white patients showed no difference from placebo. In V-HeFT II, only white patients showed a mortality reduction from enalapril therapy compared with H-I therapy (P = .02). Whites also showed evidence of greater blood pressure reduction and enhanced regression of cardiac size in response to enalapril. When stratified by history of hypertension in V-HeFT II, only whites with a history of hypertension, who had greater renin levels, showed significant mortality reduction with enalapril compared with H-I therapy. Hospitalization rates did not differ between treatment groups in either study.

CONCLUSION

Whites and blacks showed differences in cause, neurohormonal stimulation, and pharmacological response in heart failure. This retrospective analysis suggests angiotensin-converting enzyme inhibitors are particularly effective in whites, and the H-I combination can be equally effective in blacks. Prospective trials involving large numbers of black patients are needed to further clarify their response to therapy.

Nifedipine-retard versus nifedipine-capsules for the therapy of hypertensive crisis in black patients

In a randomized parallel-group placebo-controlled study, we compared the short-term hypotensive efficacy and the safety of a single administration of nifedipine-retard (20-mg tablets) with that of two administrations 6 h apart of nifedipine capsules (10 mg) in 10 and 11 black patients, respectively, with acute severe hypertension. Both groups had similar pretreatment blood-pressure (BP) values. Blood pressure was recorded at 10-min intervals for 12 h by using an automated device. In the first 3 h of treatment, nifedipine capsules induced a faster and greater hypotensive effect than nifedipine retard, which was associated with an increase in heart rate. At 2 h after treatment, nifedipine capsules decreased BP to levels (159 +/- 5/105 +/- 3 mm Hg) that were significantly lower than those reached by nifedipine-retard (175 +/- 4/118 +/- 4 mm Hg; p < 0.05). Both preparations induced a similar maximal BP decrease of approximately 30% of the placebo values, but the peak decrease of BP occurred significantly later with nifedipine-retard (283 +/- 31 min after administration) than with nifedipine capsules (100 +/- 14 min; p < 0.01). Four hours after administration, the hypotensive effect of nifedipine capsules was blunted, and a second administration was necessary, whereas nifedipine-retard reduced BP slowly and continuously for < or =12 h and more smoothly. Flush and headache were more frequently found with nifedipine capsules. We conclude that in black patients with hypertensive crisis, nifedipine capsules produce an abrupt decrease in BP that may be potentially harmful. Thus for patients suitable for treatment with nifedipine, nifedipine-retard is preferable because it effectively reduces BP for > or =12 h while achieving a rapid enough effect without critical short-term decreases in BP.

Racial differences in the renal response to blood pressure lowering during chronic angiotensin-converting enzyme inhibition: a prospective double-blind randomized comparison of fosinopril and lisinopril in older hypertensive patients with chronic renal insufficiency

This study was undertaken to compare the effects of chronic angiotensin-converting enzyme (ACE) inhibition on blood pressure (BP) and renal hemodynamics in older black and nonblack hypertensive patients with chronic renal insufficiency. A multicenter, placebo lead-in double-blind, parallel group study was performed to compare the antihypertensive efficacy and renal hemodynamic response to the once-daily ACE inhibitor fosinopril (n = 14) and lisinopril (n = 13) over a 22-week period. The study goal was to lower diastolic blood pressure (DBP) to 90 mm Hg or less. Furosemide was added after 6 weeks if blood pressure goal was not achieved. At outpatient clinics at university medical centers, 27 older hypertensive patients (> or = 45 years; 12 blacks, 15 nonblacks; 19 male, eight female) with DBP of 95 mm Hg or higher and 4-hour creatinine clearance 20 to 70 mL/min/1.73 m2 were studied. Changes (delta) from baseline in BP, glomerular filtration rate (GFR), and renal plasma flow (RPF) were measured. Mean systolic blood pressure (SBP) and DBP decreased significantly and to a similar extent in randomized groups: fosinopril (mean +/- SEM) delta DBP at 6 weeks was -13 +/- 2 (P < 0.0001; 95% CI, -16 to -9) and at 22 weeks was -12 +/- 2 (P < 0.0001; 95% CI, -16 to -9); lisinopril delta DBP at 6 weeks was -14 +/- 6 (P < 0.0001; 95% CI, -10 to -18) and at 22 weeks was -16 +/- 2 (P < 0.0001; 95% CI, -12 to -21). GFR and RPF did not change significantly in either group. BP was significantly reduced and to a similar extent in blacks and nonblacks: for blacks, delta DBP at 6 weeks was -11 +/- 3 (P < 0.05; 95% CI, -0.01 to -9) and at 22 weeks was -16 +/- 2 (P < 0.0001; 95% CI, -11 to -20); for nonblacks, delta DBP at 6 weeks was -14 +/- 1 (P < 0.0001; 95% CI, -12 to -17) and at 22 weeks was -12 +/- 2 (P < 0.0001; 95% CI, -16 to -8). Eight patients (five blacks and three nonblacks) required an addition of furosemide after 6 weeks to reach the DBP goal of < or = 90 mm Hg at 22 weeks. GFR was not significantly altered for either racial group at 6 weeks; however, at 22 weeks; however, at 22 weeks, GFR decreased significantly in blacks (delta GFR, -16 +/- 5; P < 0.006; 95% CI, -26 to -5) and tended to increase in nonblacks (delta GFR, 7 +/- 6; P > 0.25). delta GFR correlated directly with the delta RPF (delta GFR = 0.0611* delta RPF -2.35 +; r = 0.68; P < 0.003). There was no correlation between delta MAP and delta GFR or delta RPF in blacks or nonblacks. We conclude that chronic ACE inhibition with fosinopril and lisinopril alone or in combination with furosemide lowers BP in older blacks and nonblacks with hypertension and chronic renal insufficiency. Racial differences in the renal hemodynamic response to chronic ACE inhibition were noted and appear to be independent of diuretic use and the magnitude of BP lowering.

Single-drug therapy for hypertension in men. A comparison of six antihypertensive agents with placebo. The Department of Veterans Affairs Cooperative Study Group on Antihypertensive Agents

BACKGROUND

Characteristics such as age and race are often cited as determinants of the response of blood pressure to specific antihypertensive agents, but this clinically important issue has not been examined in sufficiently large trials, involving all standard treatments, to determine the effect of such factors.

METHODS

In a randomized, double-blind study at 15 clinics, we assigned 1292 men with diastolic blood pressures of 95 to 109 mm Hg, after a placebo washout period, to receive placebo or one of six drugs: hydrochlorothiazide (12.5 to 50 mg per day), atenolol (25 to 100 mg per day), captopril (25 to 100 mg per day), clonidine (0.2 to 0.6 mg per day), a sustained-release preparation of diltiazem (120 to 360 mg per day), or prazosin (4 to 20 mg per day). The drug doses were titrated to a goal of less than 90 mm Hg for maximal diastolic pressure, and the patients continued to receive therapy for at least one year.

RESULTS

The mean (+/- SD) age of the randomized patients was 59 +/- 10 years, and 48 percent were black. The average blood pressure at base line was 152 +/- 14/99 +/- 3 mm Hg. Diltiazem therapy had the highest rate of success: 59 percent of the treated patients had reached the blood-pressure goal at the end of the titration phase and had a diastolic blood pressure of less than 95 mm Hg at one year. Atenolol was successful by this definition in 51 percent of the patients, clonidine in 50 percent, hydrochlorothiazide in 46 percent, captopril in 42 percent, and prazosin in 42 percent; all these agents were superior to placebo (success rate, 25 percent). Diltiazem ranked first for younger blacks (< 60 years) and older blacks (> or = 60 years), among whom the success rate was 64 percent, captopril for younger whites (success rate, 55 percent), and atenolol for older whites (68 percent). Drug intolerance was more frequent with clonidine (14 percent) and prazosin (12 percent) than with the other drugs.

CONCLUSIONS

Among men, race and age have an important effect on the response to single-drug therapy for hypertension. In addition to cost and quality of life, these factors should be considered in the initial choice of a drug.