Parallel-group 8-week study on chlorthalidone effects in hypertensives with low kidney function.

Short-term effects of chlorthalidone are unknown in low kidney function. The effects of 8-week treatment with 25-mg chlorthalidone on the top of ongoing treatment were compared between control hypertensives and low kidney function hypertensives as assessed by estimated glomerular filtration rate <60 mL/min×1.73 m(2). Screening period consisted of 2 visits for patient selection and pretreatment laboratory evaluations (baseline). Inclusion criteria were uncontrolled hypertension on nondiuretic antihypertensive treatment. Exclusion criteria were chlorthalidone contraindications, refused consent, treatment with >3 antihypertensive drugs, severe hypertension, severe comorbidities, unreliable estimated glomerular filtration rate. Treatment period consisted of 5 visits (weeks 1, 2, 4, 6, and 8). Post-treatment laboratory evaluations were performed 3 to 4 days before week-8 visit. The 2 groups differed for baseline estimated glomerular filtration rate (low kidney function and control: n=60 and 60; mean, 39 and 76; range, 15-59 and 60-104) but not for sex, age, and baseline blood pressure. Week-8 blood pressure changes were a decrease in both groups (low kidney function and control: systolic pressure, -20 and -23; 95% confidence interval, -22/-18 and -26/-19; diastolic pressure, -9 and -10, -11/-7, and -13/-8) without significant between-group differences. Incidence of adverse events was similar in the 2 groups (15.0% and 16.7%). Baseline estimated glomerular filtration rate did not predict blood pressure changes and adverse events in either groups (P>0.6). In both groups, post-treatment changes were a decrease for estimated glomerular filtration rate and serum potassium, an increase for serum uric acid (P<0.01). Data show that short-term chlorthalidone effects were not reduced in hypertensives with low kidney function.