Antihypertensive efficacy of hydrochlorothiazide as evaluated by ambulatory blood pressure monitoring: a meta-analysis of randomized trials.

OBJECTIVES

The purpose of this study was to evaluate the antihypertensive efficacy of hydrochlorothiazide (HCTZ) by ambulatory blood pressure (BP) monitoring.

BACKGROUND

HCTZ is the most commonly prescribed antihypertensive drug worldwide. More than 97% of all HCTZ prescriptions are for 12.5 to 25 mg per day. The antihypertensive efficacy of HCTZ by ambulatory BP monitoring is less well defined.

METHODS

A systematic review was made using Medline, Cochrane, and Embase for all the randomized trials that assessed 24-h BP with HCTZ in comparison with other antihypertensive drugs.

RESULTS

Fourteen studies of HCTZ dose 12.5 to 25 mg with 1,234 patients and 5 studies of HCTZ dose 50 mg with 229 patients fulfilled the inclusion criteria. The decrease in 24-h BP with HCTZ dose 12.5 to 25 mg was systolic 6.5 mm Hg (95% confidence interval: 5.3 to 7.7 mm Hg) and diastolic 4.5 mm Hg (95% confidence interval: 3.1 to 6.0 mm Hg) and was inferior compared with the 24-h BP reduction of angiotensin-converting enzyme inhibitors (mean BP reduction 12.9/7.7 mm Hg; p < 0.003), angiotensin-receptor blockers (mean BP reduction 13.3/7.8 mm Hg; p < 0.001), beta-blockers (mean BP reduction 11.2/8.5 mm Hg; p < 0.00001), and calcium antagonists (mean BP reduction 11.0/8.1 mm Hg; p < 0.05). There was no significant difference in both systolic (p = 0.30) and diastolic (p = 0.15) 24-h BP reduction between HCTZ 12.5 mg (5.7/3.3 mm Hg) and HCTZ 25 mg (7.6/5.4 mm Hg). However, with HCTZ 50 mg, the reduction in 24-h BP was significantly higher (12.0/5.4 mm Hg) and was comparable to that of other agents.

CONCLUSIONS

The antihypertensive efficacy of HCTZ in its daily dose of 12.5 to 25 mg as measured in head-to-head studies by ambulatory BP measurement is consistently inferior to that of all other drug classes. Because outcome data at this dose are lacking, HCTZ is an inappropriate first-line drug for the treatment of hypertension.