Thiazide diuretics for hypertension: prescribing practices and predictors of use in 194,761 elderly patients with hypertension

Background — Although several small studies have reported underuse of thiazide diuretics for elderly hypertensive patients, those factors which influence initial choice of first-line antihypertensive treatment are unknown.

Objectives — The objective of this study was to explore prescribing practices for antihypertensives in the elderly and determine which factors are associated with thiazide diuretic use as first-line treatment

Methods — This population-based cohort study used linked administrative databases for all elderly patients (≥66 years of age) first treated for hypertension between July 1, 1994, and March 31, 2002, in Ontario, Canada.

Results — Of the 194,761 patients in our cohort, 68,858 (35%) were prescribed a thiazide diuretic as their first anti-hypertensive agent. On multivariate analysis, factors associated with being prescribed a thiazide as first-line treatment included age (adjusted odds ratio [AOR], 1.72 [95% CI, 1.67–1.78] for octogenarians compared with patients aged 66–69 years) and having multiple comorbidities (AOR, 1.24 [95% CI, 1.16–1.29] for Charlson scores of 2 and AOR, 1.52 [95% CI, 1.37–1.61] for Charlson scores of ≥3). On the other hand, men (AOR, 0.64 [95% CI 0.63–0.65]) and hypertensives with diabetes (AOR, 0.22 [95% CI, 0.21–0.23]) were substantially less likely to be prescribed thiazide diuretics as first-line treatment. Socioeconomic status was not associated with use of thiazide diuretics.

Conclusions — One third of initial antihypertensive prescriptions for elderly patients were for thiazides in our publicly funded healthcare system with universal drug coverage. Socioeconomic status did not influence use of thiazides, but age, sex, and comorbidities did.