Technology and Condition
Thiazide diuretics (TZD) chlorthalidone, hydrochlorothiazide, indapamide, and metolazone for primary hypertension (at least 140 mm Hg systolic or 90 mm Hg diastolic blood pressure).
Despite their demonstrated clinical effectiveness and low cost, the rate of first-line TZD use in newly treated hypertensive patients remains lower than that of angiotensin-converting enzyme (ACE) inhibitors, α-blockers (AB), angiotensin II receptor blockers (ARB), β-blockers (BB), and calcium channel blockers (CCBs). There is also uncertainty about the evidence supporting blood pressure targets.
Methods and Results
A systematic review and a meta-analysis were conducted. Clinical and quality-of-life impacts were derived from 44 RCTs. Evidence of targeting blood pressure was derived from nine trials. TZDs reduced stroke events relative to ACE inhibitors and reduced heart failure events relative to CCB, but total cardiovascular and cerebrovascular events were not significantly different. For all patient groups, TZDs represent the least costly therapeutic option and are the second most effective option behind CCB.
Implications for Decision Making
- Compelling evidence suggests that TZDs are effective first-line agents. TZDs are comparable with ACE inhibitors, BB, and CCB in reducing the risks of many adverse outcomes, including mortality. No evidence comparing TZDs with AB or ARB was found. Overall differences in quality of life were not evident.
- TZDs are least costly. Based on a simulation model of treating newly diagnosed hypertensive patients 55 and 65 years of age, TZDs represent the least costly option and the second most effective option behind CCBs. CCBs are cost-effective for those willing to pay from $400,000 to $3 million for a quality-adjusted life-year, depending on the patient’s risk of future disease.
- First-line TZDs will curb increased expenditures. If TZDs are used first-line, future increases in spending will be lower and, for some provinces, may decrease in the short term.
- No compelling evidence for lower blood pressure targets was identified. It is unclear if intensive lowering of blood pressure below the standard target (140/90 mm Hg) can significantly alter health outcomes important to patients.
This summary is based on a comprehensive health technology assessment available from CADTH’s web site (www.cadth.ca): Tran K, Ho C, Noorani HZ, Cimon K, Hodgson A, Coyle D, Coyle K, Myers MG, Wright JM. Thiazide diuretics as first-line treatment for hypertension: meta-analysis and economic evaluation.