Renewed interest in chlorthalidone: evidence from the Veterans Health Administration

Thiazide-type diuretics are recommended in national hypertension treatment guidelines, but these guidelines do not give preference to a specific thiazide. Recently, increased use of chlorthalidone has been advocated. The authors reviewed national outpatient prescription data from the Veterans Health Administration from 2003 to 2008 to describe the prescribing trends within the thiazide class, focusing on hydrochlorothiazide and chlorthalidone. Among total thiazide users, the proportion who received hydrochlorothiazide remained stable (95.6% in 2008), but the number of new users of hydrochlorothiazide decreased nearly 30% during this period. In contrast, the proportion of chlorthalidone use among total thiazide users more than doubled (1.1% in 2003 to 2.4% in 2008), and the number of new chlorthalidone users increased by more than 40%. At the time of initiation, chlorthalidone was more likely to be added to an existing antihypertensive regimen; one quarter (25.1%) of new hydrochlorothiazide starts were in patients not receiving concurrent antihypertensive medications, compared with only 12.1% for chlorthalidone (odds ratio, 0.44; 95% confidence interval, 0.42-0.46). Evaluation of national prescribing trends indicates that hydrochlorothiazide remains the most commonly prescribed thiazide, but there appears to be a shift toward more new users of chlorthalidone.