Comparison of Clinical Outcomes and Safety Associated With Chlorthalidone vs Hydrochlorothiazide in Older Adults With Varying Levels of Kidney Function

Therapeutic roles of thiazides and loop diuretics in blood pressure control and renal protection against chronic kidney disease

Fluid overload secondary to loss of functional nephron mass can elevate blood pressure, which is characteristic of hypertension shown in chronic kidney disease (CKD). Therefore, it is logical to use diuretics at appropriate dose to lower blood pressure in patients with CKD and hypertension. Despite the theoretical background on the use of diuretics in CKD, there have been no definitive data on the effectiveness or safety of diuretics as first-line therapy for the management of hypertension in patients with CKD. Results from some clinical trials have demonstrated that diuretics would not lower blood pressure. They could even worsen electrolyte imbalance and kidney function when they are administered in patients with CKD. Major clinical practice guidelines on management of blood pressure or CKD have stated that evidence for benefits of thiazide diuretics is not conclusive yet in patients with advanced CKD, although loop diuretics are often effective for volume control at lower glomerular filtration rate. Recently, evidence for diuretics as effective blood pressure lowering agents in patients with advanced CKD is increasing. Renoprotective effect of thiazide or loop diuretics might represent a consequence of their influence on blood pressure or their ability to potentiate the effect of renin-angiotensin system blockade by making intraglomerular pressure more renin-angiotensin system-dependent, although their direct benefit on renal function remains controversial. This review summarizes recent data on the possible role of diuretics in lowering blood pressure, slowing the progression of kidney disease, and reducing cardiovascular risk in CKD patients.

Comparison of the Effectiveness and Safety of Chlorthalidone and Hydrochlorothiazide in Patients With Hypertension: A Meta-Analysis

The aim of this study was to compare the effectiveness and safety of chlorthalidone and hydrochlorothiazide in patients with hypertension. The present meta-analysis was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Our search for relevant articles was conducted on PubMed, Scopus, and CINAHIL databases from their inception until March 31, 2023. Keywords used to search for relevant articles included "hydrochlorothiazide," "chlortalidone," "hypertension," "cardiovascular," and "blood pressure." The outcomes assessed in this meta-analysis included changes in systolic blood pressure (SBP) and diastolic blood pressure (DBP). Myocardial infarction, stroke, and all-cause mortality were also assessed. For safety analysis, we evaluated the risk of hypokalemia between the two groups. Any disagreement between the two authors in the data extraction process was resolved through discussion. Eight studies fulfilled the inclusion criteria included in the present meta-analysis. Our analysis showed that chlorthalidone was superior to hydrochlorothiazide in controlling both SBP and DBP, with no significant heterogeneity reported. However, there was no significant difference between the two groups in terms of the risk of myocardial infarction, stroke, all-cause mortality, and hospitalization due to heart failure. The hypokalemia rate was reported to be higher with chlorthalidone compared to hydrochlorothiazide.

Chlorthalidone vs. Hydrochlorothiazide for Hypertension-Cardiovascular Events

BACKGROUND

Whether chlorthalidone is superior to hydrochlorothiazide for preventing major adverse cardiovascular events in patients with hypertension is unclear.

METHODS

In a pragmatic trial, we randomly assigned adults 65 years of age or older who were patients in the Department of Veterans Affairs health system and had been receiving hydrochlorothiazide at a daily dose of 25 or 50 mg to continue therapy with hydrochlorothiazide or to switch to chlorthalidone at a daily dose of 12.5 or 25 mg. The primary outcome was a composite of nonfatal myocardial infarction, stroke, heart failure resulting in hospitalization, urgent coronary revascularization for unstable angina, and non-cancer-related death. Safety was also assessed.

RESULTS

A total of 13,523 patients underwent randomization. The mean age was 72 years. At baseline, hydrochlorothiazide at a dose of 25 mg per day had been prescribed in 12,781 patients (94.5%). The mean baseline systolic blood pressure in each group was 139 mm Hg. At a median follow-up of 2.4 years, there was little difference in the occurrence of primary-outcome events between the chlorthalidone group (702 patients [10.4%]) and the hydrochlorothiazide group (675 patients [10.0%]) (hazard ratio, 1.04; 95% confidence interval, 0.94 to 1.16; P = 0.45). There were no between-group differences in the occurrence of any of the components of the primary outcome. The incidence of hypokalemia was higher in the chlorthalidone group than in the hydrochlorothiazide group (6.0% vs. 4.4%, P<0.001).

CONCLUSIONS

In this large pragmatic trial of thiazide diuretics at doses commonly used in clinical practice, patients who received chlorthalidone did not have a lower occurrence of major cardiovascular outcome events or non-cancer-related deaths than patients who received hydrochlorothiazide. (Funded by the Veterans Affairs Cooperative Studies Program; ClinicalTrials.gov number, NCT02185417.).

Use of Thiazides to Treat Hypertension and Advanced CKD

PURPOSE OF REVIEW

Hypertension is often difficult to control in patients with CKD as manifested by suboptimal control rates in this population. Use of thiazides in CKD patients has been limited as these agents are thought to be ineffective in reducing blood pressure in people with advanced CKD. This review summarizes recent studies impacting indications and safety of use of thiazide in patients with CKD and discusses the mechanism of how thiazides reduce blood pressure.

RECENT FINDINGS

Chlorthalidone reduces blood pressure compared to placebo in patients with advanced CKD, challenging the belief that thiazide diuretics lose efficacy at lower levels of GFR. Recent clinical trial data indicate that thiazides are effective in patients with advanced kidney disease for blood pressure lowering. However, monitoring of electrolytes and kidney function is important to ensure patient safety when prescribing these agents in patients with CKD.

Revisiting diuretic choice in chronic kidney disease

PURPOSE OF REVIEW

Existing guidelines offer little direction about the use of thiazide and loop diuretics in patients with chronic kidney disease (CKD). This review summarizes recent studies impacting indications and safety considerations for these agents in patients with CKD.

RECENT FINDINGS

Chlorthalidone reduces blood pressure compared to placebo in patients with advanced CKD, challenging the belief that thiazide diuretics lose efficacy at lower glomerular filtration rates (GFR). Existing studies show no clear impact of thiazide or loop diuretic use on kidney or cardiovascular outcomes in patients with CKD. Sodium-glucose co-transporter type 2 (SGLT2) inhibitors have diuretic effects, but concomitant use of a diuretic does not diminish the preventive benefits of these agents against acute kidney injury (AKI). Despite theoretical concerns, thiazide diuretics likely do not worsen circulating vasopressin levels or cyst progression in polycystic kidney disease and may be useful for alleviating polyuria from tolvaptan. Diuretics cause multiple adverse effects, including electrolyte abnormalities, hemodynamic-mediated decrease in estimated GFR, and AKI.

SUMMARY

Recent evidence supports expanded indications for diuretics in patients with kidney disease, including chlorthalidone for hypertension in advanced CKD. Monitoring electrolytes and estimated GFR is critical to ensure patient safety when prescribing these agents for patients with CKD.

Thiazide and the Thiazide-Like Diuretics: Review of Hydrochlorothiazide, Chlorthalidone, and Indapamide

The term thiazide is universally understood to refer to diuretics that exert their principal action in the distal tubule. The thiazide class is heterogenous and can be further subdivided into compounds containing the benzothiadiazine ring structure-the thiazide-type (e.g., hydrochlorothiazide)-and those lacking the benzothiadiazine ring-the thiazide-like (e.g., chlorthalidone and indapamide) drugs. Thiazide-like agents are longer acting and constitute the diuretics used in most of the cardiovascular outcome trials that established benefits of treatment with diuretics, but pragmatic aspects, such as lack of availability in convenient formulations, limit their use. Regardless of class heterogeneity, thiazides have retained importance in the management of hypertension for over 60 years. They are reliably effective as monotherapy in a majority of hypertensive patients, and augment the efficacy of other classes of antihypertensives when used in combination. Importantly, a thiazide-based treatment regimen lowers cardiovascular events, and their sturdy effect reinforces their place among the recommended first-line agents to treat hypertension in major domestic and international hypertension guidelines. There are few head-to-head comparisons within the class, but potential differences have been explored indirectly as well as in non-blood pressure mechanisms and potential pleiotropic properties. Until proven otherwise, the importance of these differences remains speculative, and clinicians should assume that cardiovascular events will be lowered similarly across agents when equivalent blood pressure reduction occurs. Thiazides remain underutilized, with only about one-third of hypertensive patients receiving them. For many patients, however, a thiazide is an indispensable component of their regimen to achieve adequate blood pressure control.