Chlorthalidone versus hydrochlorothiazide: major cardiovascular events, blood pressure, left ventricular mass, and adverse effects.

BACKGROUND: There is continuous debate whether chlorthalidone (CTD) and hydrochlorothiazide (HCTZ) differ in reducing major cardiovascular events (MACE). HCTZ is prescribed 10 times more commonly than CTD. METHOD: A systematic literature search yielded 14 references, including two network meta-analyses of randomized trials with MACE and left ventricular mass as outcomes. RESULTS: The network meta-analysis of randomized trials showed CTD reducing MACE more than HCTZ, hazard ratio = 0.79 (0.72-0.88), P < 0.0001, and an observational cohort study gave an identical point estimate: hazard ratio = 0.79 (0.68-0.92), P = 0.002. In contrast, two observational cohort studies reported no differences between CTD and HCTZ. However, in the studies showing the superiority of CTD median follow-up was 4.3 and 7.0 years, respectively, whereas in the latter studies showing no difference between the two drugs follow-up was only 0.95 and 0.25 years. As differences in outcomes for MACE in hypertension trials with various interventions only emerge after prolonged (>1 year) therapy, differences in follow-up explain these discrepant results. CTD also more effectively reduced left ventricular mass in observational data and network analysis of trials. These advantages of CTD over HCTZ are consistent with greater reductions in night-time blood pressure, greater reductions in oxidative stress and platelet aggregation, and greater improvements in endothelial function. CONCLUSION: Over the short-term there were no differences in the net clinical benefit between HCTZ and CTD. However, long-term available data document CTD to be significantly more effective in reducing MACE than HCTZ. The Veterans Administration's trial in progress may provide definitive answer to these questions.

Obesity-Induced Hypertension: Heavy on the Accelerator.

See Article Fan et al.

Does the benefit from treating to lower blood pressure targets vary with age? A systematic review and meta-analysis.

BACKGROUND: Recommendations differ regarding how blood pressure targets should vary with age. Crucial to this controversy is whether treatment benefit varies with age. METHODS: Systematic searches were conducted for trials randomizing treatment in intensive arms to the recommended SBP targets: 120-140 mmHg. Head-to-head meta-analyses and meta-regression were conducted. RESULTS: Sixteen trials met criteria. Relative to higher targets, lower targets reduced cardiovascular events, but treatment benefit differed significantly among trials due to patient age. Treatment significantly benefited older patients (mean age 77, SD = 72-81), relative risk (RR) = 0.77 (0.61,0.97), P = 0.025, but not younger patients (mean age 61, SD = 53-70), RR = 0.90 (0.78,1.03), P = 0.121, even though the latter had much greater statistical power. The (RR in 80 year olds)/(RR in 55 year olds) = 0.68 (0.47,0.97), P = 0.036. Though statistically nonsignificant, corresponding trends for more specific outcomes favored older patients: Coronary artery disease 0.80, stroke 0.85, heart failure 0.54, and total mortality 0.76. For adverse effects this trend was 0.86 (0.33,2.26). The number needed to treat to lower targets to prevent one cardiovascular event over 10 years in eight populations declined with age by 94%+. CONCLUSION: In these novel results, for both RR and absolute risk, treating to SBPs of 120-140 mmHg versus higher targets benefited older patients more than younger patients without an age-related increase in the RR for adverse effects. Nonetheless, because all clinical trials excluded the most frail older patients, clinicians must consider individual patient characteristics such as frailty, autonomy, and cognitive ability when choosing blood pressure targets.

Hydrochlorothiazide vs chlorthalidone, indapamide, and potassium-sparing/hydrochlorothiazide diuretics for reducing left ventricular hypertrophy: A systematic review and meta-analysis.

Left ventricular hypertrophy develops in 36%-41% of hypertensive patients and independently predicts cardiovascular events and total mortality. Moreover, drug-induced reduction in left ventricular mass (LVM) correlates with improved prognosis. The optimal thiazide-type diuretic for reducing LVM is unknown. Evidence regarding potency, cardiovascular events, sodium, and potassium suggested the hypothesis that "CHIP" diuretics (CHlorthalidone, Indapamide, and Potassium-sparing diuretic/hydrochlorothiazide [PSD/HCTZ]) would reduce LVM more than HCTZ. Systematic searches of five databases were conducted. Among the 38 randomized trials, a 1% reduction in systolic blood pressure (SBP) predicted a 1% reduction in LVM, P = 0.00001. CHIP-HCTZ differences in reducing LVM differed across trials (ie, heterogeneity), making interpretation uncertain. However, among the 28 double-blind trials, heterogeneity was undetectable, and HCTZ reduced LVM (percent reduction [95% CI]) by -7.3 (-10.4, -4.2), P < 0.0001. CHIP diuretics surpassed HCTZ in reducing LVM: chlorthalidone -8.2 (-14.7, -1.6), P = 0.015; indapamide -7.5 (-12.7, -2.3), P = 0.005; and all CHIP diuretics combined -7.7 (-12.2, -3.1), P < 0.001. The comparison of PSD/HCTZ with HCTZ had low statistical power but favored PSD/HCTZ: -6.0 (-14.1, +2.1), P = 0.149. Thus, compared to HCTZ, CHIP diuretics had twice the effect on LVM. CHIP diuretics did not surpass HCTZ in reducing systolic or diastolic blood pressure: -0.3 (-5.0, +4.3) and -1.6 (-5.6, +2.4), respectively. The strength of evidence that CHIP diuretics surpass HCTZ for reducing LVM was high (GRADE criteria). In conclusion, these novel results have demonstrated that CHIP diuretics reduce LVM 2-fold more than HCTZ among hypertensive patients. Although generally related to LVM, blood pressure fails to explain the superiority of CHIP diuretics for reducing LVM.

Hydrochlorothiazide and alternative diuretics versus renin-angiotensin system inhibitors for the regression of left ventricular hypertrophy: a head-to-head meta-analysis.

BACKGROUND: Found in 36-41% of hypertension, elevated left ventricular mass (LVM) independently predicts cardiovascular events and total mortality. Conversely, drug-induced regression of LVM predicts improved outcomes. Previous studies have favored renin-angiotensin system inhibitors (RASIs) over other antihypertensives for reducing LVM but ignored differences among thiazide-type diuretics. From evidence regarding potency, cardiovascular events, and electrolytes, we hypothesized a priori that 'CHIP' diuretics [CHlorthalidone, Indapamide and Potassium-sparing Diuretic/hydrochlorothiazide (PSD/HCTZ)] would rival RASIs for reducing LVM. METHOD AND RESULTS: Systematic review yielded 12 relevant double-blind randomized trials. CHIPs were more closely associated with reduced LVM than HCTZ (P = 0.004), indicating that RASIs must be compared with each diuretic separately. Publication bias favoring RASIs was corrected by cumulative analysis. For reducing LVM, HCTZ tended to be less effective than RASIs. However, the following surpassed RASIs: chlorthalidone Hedge's G: -0.37 (95% CI -0.72 to -0.02), P = 0.036; indapamide -0.20 (-0.39 to -0.01), P = 0.035; all CHIPs combined (with 61% of patients in one trial) -0.25 (-0.41to -0.09), P = 0.002. Statistical significance (P < 0.05) did not depend on any one trial. CHIPs reduction in LVM was 37% greater than that from RASIs. CHIPs superiority tended to increase with trial duration, from a negligible effect at 0.5 year to a maximal effect at 0.9-1.0 years: -0.26 (-0.43 to -0.09), P = 0.003. Fifty-eight percent of patients had information on echocardiographic components of LVM: relative to RASIs, CHIPs significantly reduced end-diastolic LV internal dimension (EDLVID): -0.18 (-0.36 to -0.00), P = 0.046. Strength of evidence favoring CHIPs over RASIs was at least moderate. CONCLUSION: In these novel results in patients with hypertension, CHIPs surpassed RASIs for reducing LVM and EDLVID.

Quality of Meta-Analyses for Randomized Trials in the Field of Hypertension: an Updated and Improved Systematic Review.

Publications of hypertension-related meta-analyses (MAs) have increased exponentially in the past 25 years and now average 8/month. Theoretically, this is facilitating evidence-based management of patients. However, some practitioners and authors of guidelines have questioned the quality of published MAs. By extending a prior review, we have assessed the quality of 212 hypertension-related meta-analyses over 5 years based on systematically searching three computerized libraries. Seventeen criteria grouped into four domains of quality yielded the following results: (1) Assessment of trial quality was accomplished in 89% of MAs, and 38% analyzed trials in subgroups of trial quality where appropriate. (2) All three measures of heterogeneity (I 2, tau, and P for heterogeneity) were reported in 36%, reflecting the failure to report tau, the standard deviation of the main effect. (3) Publication bias was assessed in 75%, and 43% of MAs used a statistical test for publication bias. (4) Regarding transparency, 9 to 31% of MAs reported problems in the previous three domains in the article's abstract. Journal impact factor reporting the MAs declined significantly over 5 years. The percent with criteria of quality in a MA was modestly correlated with journal impact factor (R 2 = 0.05, P = 0.001). False-positive results from inappropriate application of the DerSimonian-Laird model affected 25% of articles, which reported these false positives in the article's abstract in 72%. No more than 25% of MAs had 67% or more of the criteria of quality. In conclusion, skepticism of hypertension-related MAs is justified, but their quality can be readily corrected.

Quality of meta-analyses for randomized trials in the field of hypertension: a systematic review.

OBJECTIVES: Doubling on average every 6 years, hypertension-related meta-analyses are now published twice weekly and are often considered the highest level of evidence for clinical practice. However, some hypertension specialists and guideline authors view meta-analyses with skepticism. This article evaluates the quality of hypertension-related meta-analyses of clinical trials. METHODS: A systematic search was conducted for meta-analyses of clinical trials recently published over 3.3 years. Specific criteria reproducibly assessed 26 features in the four domains of meta-analysis quality, domains justified by fundamental analytics and extensive research: analyzing trial quality, analyzing heterogeneity, analyzing publication bias, and providing transparency. RESULTS: A total of 143 meta-analyses were identified. A total of 44% had 8+ deficient features with no relation to journal impact factor: odds ratio relating 8+ deficient features to the upper third versus lower third of impact factor = 1.3 (95% confidence limit 0.6-2.9). A total of 56% had all four domains deficient. Quality did not improve over time. Thirty articles (21%) reported statistically significant results (P < 0.05) from inappropriate DerSimonian-Laird models, whereas unreported, appropriate, Knapp-Hartung models gave statistical nonsignificance; 88% of these 30 articles reported the incorrect results in their abstracts. A total of 60% of all meta-analyses failed to conduct analyses in subgroups of quality when indicated, 63% failed to report Tau and Tau, 57% omitted testing for publication bias, none conducted a cumulative analysis for publication bias, and 71-77% omitted mentioning in their abstracts problems of trial quality, heterogeneity, and publication bias. CONCLUSION: Although widespread, deficiencies in hypertension-related meta-analyses are readily corrected and do not represent flaws inherent in the meta-analytic method.

Diuretics for Hypertension: A Review and Update.

This review and update focuses on the clinical features of hydrochlorothiazide (HCTZ), the thiazide-like agents chlorthalidone (CTDN) and indapamide (INDAP), potassium-sparing ENaC inhibitors and aldosterone receptor antagonists, and loop diuretics. Diuretics are the second most commonly prescribed class of antihypertensive medication, and thiazide-related diuretics have increased at a rate greater than that of antihypertensive medications as a whole. The latest hypertension guidelines have underscored the importance of diuretics for all patients, but particularly for those with salt-sensitive and resistant hypertension. HCTZ is 4.2-6.2 systolic mm Hg less potent than CTDN, angiotensin-converting enzyme inhibitors, beta blockers, and calcium channel blockers by 24-hour measurements and 5.1mm Hg systolic less potent than INDAP by office measurements. For reducing cardiovascular events (CVEs), HCTZ is less effective than enalapril and amlodipine in randomized trials, and, in network analysis of trials, it is less effective than CTDN and HCTZ-amiloride. Combined with thiazide-type diuretics, potassium-sparing agents decrease ventricular ectopy and reduce the risk for sudden cardiac death relative to thiazide-type diuretics used alone. A recent synthesis of 44 trials has shown that the relative potencies in milligrams among spironolactone (SPIR), amiloride, and eplerenone (EPLER) are approximately from 25 to 10 to 100, respectively, which may be important when SPIR is poorly tolerated. SPIR reduces proteinuria beyond that provided by other renin angiotensin aldosterone inhibitors. EPLER also reduces proteinuria and has beneficial effects on endothelial function. While guidelines often do not differentiate among specific diuretics, this review demonstrates that these distinctions are important for managing hypertension.

Prognostic Effect of the Nocturnal Blood Pressure Fall in Hypertensive Patients: The Ambulatory Blood Pressure Collaboration in Patients With Hypertension (ABC-H) Meta-Analysis.

The prognostic importance of the nocturnal systolic blood pressure (SBP) fall, adjusted for average 24-hour SBP levels, is unclear. The Ambulatory Blood Pressure Collaboration in Patients With Hypertension (ABC-H) examined this issue in a meta-analysis of 17 312 hypertensives from 3 continents. Risks were computed for the systolic night-to-day ratio and for different dipping patterns (extreme, reduced, and reverse dippers) relative to normal dippers. ABC-H investigators provided multivariate adjusted hazard ratios (HRs), with and without adjustment for 24-hour SBP, for total cardiovascular events (CVEs), coronary events, strokes, cardiovascular mortality, and total mortality. Average 24-hour SBP varied from 131 to 140 mm Hg and systolic night-to-day ratio from 0.88 to 0.93. There were 1769 total CVEs, 916 coronary events, 698 strokes, 450 cardiovascular deaths, and 903 total deaths. After adjustment for 24-hour SBP, the systolic night-to-day ratio predicted all outcomes: from a 1-SD increase, summary HRs were 1.12 to 1.23. Reverse dipping also predicted all end points: HRs were 1.57 to 1.89. Reduced dippers, relative to normal dippers, had a significant 27% higher risk for total CVEs. Risks for extreme dippers were significantly influenced by antihypertensive treatment (P<0.001): untreated patients had increased risk of total CVEs (HR, 1.92), whereas treated patients had borderline lower risk (HR, 0.72) than normal dippers. For CVEs, heterogeneity was low for systolic night-to-day ratio and reverse/reduced dipping and moderate for extreme dippers. Quality of included studies was moderate to high, and publication bias was undetectable. In conclusion, in this largest meta-analysis of hypertensive patients, the nocturnal BP fall provided substantial prognostic information, independent of 24-hour SBP levels.

Dose doubling, relative potency, and dose equivalence of potassium-sparing diuretics affecting blood pressure and serum potassium: systematic review and meta-analyses.

BACKGROUND: Potassium-sparing diuretics (PSDs) are valuable antihypertensives with additional benefits unrelated to control of systolic blood pressure (SBP). However, their key parameters affecting SBP and serum potassium are poorly defined, fostering underutilization. METHOD: Consequently, we conducted systematic reviews and meta-analyses, yielding 3668 articles and ultimately 84 randomized comparisons. RESULTS: For office SBP, overall placebo-adjusted changes were triamterene -1.9 (low dose only), amiloride -9.9, spironolactone -13.2, and eplerenone -9.2. Differences in antihypertensive effect were due to potency rather than efficacy. Doubling amiloride, eplerenone, and spironolactone doses reduced SBP (95% confidence limits) on average by -2.3 (-3.1, -1.5). Relative antihypertensive potencies were spironolactone>amiloride>eplerenone. Spironolactone had significantly greater antihypertensive potency than amiloride, -4.0 (-7.4, -0.6), and eplerenone, -5.5 (-7.4, -3.6). Dose equivalencies were eplerenone-spironolactone 4.5-to-1 (e.g., eplerenone 125∼spironolactone 25), amiloride-spironolactone 3.3-to-1, and eplerenone-amiloride 1.4-to-1. Increases in serum potassium from amiloride and spironolactone at commonly used doses averaged 0.14-0.29 mEq/l; the dose doubling effect was 0.16 (0.10, 0.22). Spironolactone caused greater hyperkalemia than amiloride across their dose ranges: 0.14, P = 0.043. Seven features make important bias unlikely: a comprehensive literature search, adjustment for covariates, all models explaining 95-100% of the between-study variability, similar dose doubling effects among PSDs, two different methods giving the same potency sequence, similar results from double blind comparisons, and similar results for eplerenone versus spironolactone from analysing direct comparison data (i.e., no meta-regression) for office and 24-h SBP. CONCLUSION: This synthesis accomplishes for PSDs what has already been achieved for thiazide-type diuretics and other antihypertensives and can guide the application of these underutilized medicines.

Head-to-head comparisons of hydrochlorothiazide with indapamide and chlorthalidone: antihypertensive and metabolic effects.

Hydrochlorothiazide (HCTZ) has often been contrasted with chlorthalidone, but relatively little is known about HCTZ versus indapamide (INDAP). This systematic review retrieved 9765 publications, and from these, it identified 14 randomized trials with 883 patients comparing HCTZ with INDAP and chlorthalidone on antihypertensive potency or metabolic effects. To make fair comparisons, the dose of the diuretic in each arm was assigned 1 of 3 dose levels. In random effects meta-analysis, INDAP and chlorthalidone lowered systolic blood pressure more than HCTZ: -5.1 mm Hg (95% confidence interval, -8.7 to -1.6); P=0.004 and -3.6 mm Hg (95% confidence interval, -7.3 to 0.0); P=0.052, respectively. For both comparisons, there was minimal heterogeneity in effect across trials and no evidence for publication bias. The HCTZ-INDAP contrast was biased in favor of greater HCTZ potency because of a much greater contribution to the overall effect from trials in which the HCTZ arm had a higher dose level than the INDAP arm. For the HCTZ-INDAP comparison, no single trial was responsible for the overall result nor was it possible to detect significant modifications of this comparison by duration of follow-up, high- versus low-bias trials, or the presence or absence of background medications. There were no detectable differences between HCTZ and INDAP in metabolic adverse effects, including effects on serum potassium. In conclusion, these head-to-head comparisons demonstrate that, like chlorthalidone, INDAP is more potent than HCTZ at commonly prescribed doses without evidence for greater adverse metabolic effects.

Not just chlorthalidone: evidence-based, single tablet, diuretic alternatives to hydrochlorothiazide for hypertension.

Accounting for 15 % of deaths worldwide, hypertension is often treated with hydrochlorothiazide (HCTZ) (50 million prescriptions annually). HCTZ has a <24-h duration of action, is less potent than chlorthalidone and all major antihypertensive drug classes, and is inferior to four antihypertensive drugs for cardiovascular event (CVE) reduction. If there were alternative diuretics, why prescribe HCTZ? Chlorthalidone is often offered as an alternative to HCTZ, but has limited pharmaceutical formulations. However, there are seven evidence-based, single-tablet, alternative diuretics. For reducing CVE, the following are superior to their comparators: chlorthalidone versus four antihypertensives in multiple hypertensive populations; indapamide versus placebo in elderly Chinese (and versus enalapril for left ventricular hypertrophy), triamterene-HCTZ versus placebo in elderly Europeans, amiloride-HCTZ versus three antihypertensives, and indapamide-perindopril versus placebo in three populations. Additionally, chlorthalidone-azilsartan and spironolactone-HCTZ are potent combinations The aldosterone antagonist component of the latter combination has been shown to reduce total mortality by 30 % in heart failure. Five of these seven have multiple dose formulations. Six cost $4-$77 monthly. In conclusion, based on both scientific and practical grounds, new prescriptions for HCTZ are rarely justified.

Prognostic impact of sex-ambulatory blood pressure interactions in 10 cohorts of 17 312 patients diagnosed with hypertension: systematic review and meta-analysis.

BACKGROUND: Whether ambulatory blood pressure (BP) among hypertensive patients better predicts cardiovascular events (CVEs) in women relative to men is unclear. METHODS: We searched PUBMED and OVID databases. Cohorts were required to have hypertension, 1+ years of follow-up, with stroke and coronary artery disease as outcomes. Lead investigators for these cohorts provided ad hoc analyses. Random-effect meta-analyses gave hazard ratios for CVEs from a 1 standard deviation (SD) mmHg increase and a 10 mmHg increase in SBP. Subgroup and meta-regression analyses quantified the relative increase in risk in women versus men. RESULTS: Patients were from Europe, Brazil, and Japan (10 cohorts, n = 17 312, CVEs = 1892). One cohort lacked sex-specific hazard ratios from 24 h and clinic SBP. Compared with men, women tended to have greater SDs and coefficients of variation of SBP. Subgroup analyses showed higher hazard ratios in women than in men from increases in ambulatory but not clinic SBPs. For women relative to men, a 1 SD increase in night-time, daytime, 24 h, and clinic SBP gave hazard ratios (95% confidence limits) of 1.17 (1.06-1.30), 1.24 (1.10-1.39), 1.21 (1.08-1.36), and 0.94 (0.84-1.05), respectively, whereas a 10 mmHg increase in SBP, gave hazard ratios of 1.06 (0.99-1.14), 1.13 (1.03-1.23), 1.10 (1.01-1.21), and 0.96 (0.89-1.03), respectively. CONCLUSION: In patients with hypertension, increases in ambulatory, but not clinic, SBP predict higher risks for CVEs in women than in men. Although women tended to have greater variability in SBP, this did not entirely explain the sex-ambulatory BP interactions.

Prognostic impact from clinic, daytime, and night-time systolic blood pressure in nine cohorts of 13,844 patients with hypertension.

BACKGROUND AND METHOD: To determine which SBP measure best predicts cardiovascular events (CVEs) independently, a systematic review was conducted for cohorts with all patients diagnosed with hypertension, 1+ years follow-up, and coronary artery disease and stroke outcomes. Lead investigators provided ad hoc analyses for each cohort. Meta-analyses gave hazard ratios from clinic SBP (CSBP), daytime SBP (DSBP), and night-time SBP (NSBP). Coefficients of variation of SBP measured dispersion. Nine cohorts (n = 13,844) were from Europe, Brazil, and Japan. For sleep-wake SBP classification, seven cohorts used patient-specific information. RESULTS: Overall, NSBP's dispersion exceeded DSBP's dispersion by 22.6% with nonoverlapping confidence limits. Within all nine cohorts, dispersion for NSBP exceeded that for CSBP and DSBP. For each comparison, P = 0.004 that this occurred by chance. Considered individually, increases in NSBP, DSBP, and CSBP each predicted CVEs: hazard ratios (95% confidence intervals) = 1.25 (1.22-1.29), 1.20 (1.15-1.26), and 1.11 (1.06-1.16), respectively. However, after simultaneous adjustment for all three SBPs, hazard ratios were 1.26 (1.20-1.31), 1.01 (0.94-1.08), and 1.00 (0.95-1.05), respectively. Cohorts with baseline antihypertensive treatment and cohorts with patient-specific information for night-day BP classification gave similar results. Within most cohorts, simultaneously adjusted hazard ratios were greater for NSBP than for DSBP and CSBP: P = 0.023 and 0.012, respectively, that this occurred by chance. CONCLUSION: In hypertensive patients, NSBP had greater dispersion than DSBP and CSBP in all cohorts. On simultaneous adjustment, compared with DSBP and CSBP, increased NSBP independently predicted higher CVEs in most cohorts, and, overall, NSBP independently predicted CVEs, whereas CSBP and DSBP lost their predictive ability entirely.

Evening dosing of antihypertensive therapy to reduce cardiovascular events: a third type of evidence based on a systematic review and meta-analysis of randomized trials.

Nighttime blood pressure strongly predicts cardiovascular events (CVEs). Further, a preliminary trial has shown decreased CVEs from evening vs morning dosing of antihypertensive therapy. Is there additional evidence for evening dosing? The authors systematically classified all hypertension trials as evening dosing trials (EDTs) or usual dosing trials (UDTs). Meta-analyses provided standardized hazard ratios for CVEs for EDTs (HREDT s ) and UDTs (HRUDT s ). HREDT s /HRUDT s gave the relative risk (RR) from evening vs usual dosing. Among 175 trials, 5 EDTs were discovered. The RR for CVEs (95% confidence limits) from evening vs usual dosing was 0.63 (0.43-0.92; P=.016). After adjustment for drug class, the RR was 0.54 (0.34-0.85; P=.008). Unlike other EDTs, the Heart Outcomes Prevention Evaluation (HOPE) study administered its entire antihypertensive dose prior to sleep and gave the greatest risk reduction. This study provides a third type of evidence suggesting a beneficial effect from evening dosing of antihypertensive therapy. Head-to-head, multicenter trials are needed to test this strategy.

Diuretics: a review and update.

Diuretics have been recommended as first-line treatment of hypertension and are also valuable in the management of hypervolemia and electrolyte disorders. This review summarizes the key features of the most commonly used diuretics. We then provide an update of clinical trials for diuretics during the past 5 years. Compared to other classes of medications, thiazide diuretics are at least as effective in reducing cardiovascular events (CVEs) in patients with hypertension and are more effective than ß-blockers and angiotensin-converting enzyme inhibitors in reducing stroke. Observational cohort data and a network analysis have shown that CVEs are lowered by one-fifth from chlorthalidone when compared to the commonly used thiazide, hydrochlorothiazide. Relative to placebo, chlorthalidone increases life expectancy. In those aged 80 years and older, the diuretic, indapamide, lowers CVEs relative to placebo. The aldosterone antagonist, eplerenone, lowers total mortality in early congestive heart failure. The benefit of eplerenone following acute myocardial infarction (MI) is limited to administration within 3 to 6 days post-MI. Aldosterone antagonists have been shown to lower the incidence of sudden cardiac death and to reduce proteinuria. In the setting of heart failure, long acting loop diuretics azosemide and torasemide are more effective in improving heart failure outcomes than the far more commonly used short acting furosemide. Evening dosing of diuretics appears to lower CVEs relative to morning dosing. In conclusion, diuretics are a diverse class of drugs that remain extremely important in the management of hypertension and hypervolemic states.

Chlorthalidone: mechanisms of action and effect on cardiovascular events.

How chlorthalidone (CTDN) reduces risk for cardiovascular events (CVEs) can be considered in light of its ability to lower blood pressure (BP) and its non-BP related, pleiotropic effects. The mechanism by which CTDN lowers BP is unclear but may include alterations in whole body regulation and vasodilatory actions on vasculature, possibly mediated via its inhibitory effects on carbonic anhydrase. Additionally, CTDN has potentially beneficial, non-BP related, pleiotropic effects that include improvements in endothelial function, anti-platelet activity, and oxidative status. CTDN reduces pulse wave velocity, predictor of CVEs and a measure of central aortic stiffness associated with endothelial dysfunction. On the other hand, CTDN fosters hypokalemia, hyperglycemia, sympathetic discharge, and the renin-angiotensin-aldosterone system, but these potentially harmful effects do not appear to materially reduce CTDN's ability to prevent CVEs. Further, CTDN reduces and regresses left ventricular hypertrophy (LVH), an important BP-dependent predictor of CVEs. Consistent with this finding, CTDN was more effective than amlodipine in reducing congestive heart failure (CHF) in the Anti-hypertensive and Lipid-lowering Treatment to Prevent Heart Attach Trial (ALLHAT). In reducing CVEs, CTDN was superior to lisinopril in ALLHAT and superior to hydrochlorthiazide in observational cohort analyses and in network analyses of randomized trials. A statistical synthesis of randomized trials suggests that the reduction in cardiovascular risk from CTDN can be explained primarily on the basis of its ability to lower blood pressure rather than its influence upon non-BP related, pleiotropic effects.

Is chlorthalidone better than hydrochlorothiazide in reducing cardiovascular events in hypertensives?

PURPOSE OF REVIEW: Hydrochlorthiazide (HCTZ) is the tenth most commonly prescribed drug in recent data. Although no head-to-head trials compare HCTZ with the uncommonly prescribed chlorthalidone (CTDN) in reducing cardiovascular events (CVEs), numerous other data are available. RECENT FINDINGS: Head-to-head trials have shown CTDN's superiority in antihypertensive potency, particularly during the critical nighttime period (SBP difference 7.1 mmHg), due to the differences in duration of action (16-24 h for HCTZ versus 48-72 h for CTDN). In an observational cohort study, compared with HCTZ, CTDN was associated with lower left ventricular hypertrophy. In another observational cohort analysis (n = 12,866), the percentage risk reduction in CVEs from CTDN versus HCTZ was 21 [95% confidence interval (CI) 8-32], P = 0.002. In network meta-analyses of randomized trials (n = 50,946), CTDN was superior to HCTZ in reducing congestive heart failure and in reducing all CVEs: percentage risk reduction 21 (95% CI 12-28), P < 0.0001. A statistically significant reduction in CVEs by CTDN versus HCTZ persisted even when reduction in office SBP produced by the two diuretics was identical, further strengthening the case for CTDN. SUMMARY: Direct and indirect evidence demonstrates that CTDN is superior to HCTZ in reducing CVEs and is congruent with the recent changes in the guidelines for hypertension management.