title: Thiazides diuretics in the treatment of nephrolithiasis: are we using them in an evidence-based fashion?
abstract: In the 1980s a change occurred in hydrochlorothiazide prescribing practices for hypertension from high-dose (50 mg/day) to low-dose (12.5-25 mg/day) therapy. However, randomized controlled trials (RCT) for prevention of calcium-containing kidney stones (CCKS) employed only high doses (≥ 50 mg/day). We hypothesized that these practices have resulted in underdosing of hydrochlorothiazide for prevention of CCKS. Patients with a filled prescription for thiazide diuretics that underwent a 24-h urine stone risk factor analysis were eligible. Those with evidence that thiazide was prescribed for CCKS were further analyzed. Of 107 patients, 102 were treated with hydrochlorothiazide, 4 with indapamide, and one with chlorthalidone. Only 35% of hydrochlorothiazide-treated patients received 50 mg/day; a dose previously shown to reduce stone recurrence. Fifty-two percent were prescribed 25 mg and 13% 12.5 mg daily, doses that were not studied in RCT. Evidence-based hydrochlorothiazide use was suboptimal regardless of where the patient received care (Nephrology or Endocrinology clinic). In a small subset of patients (n = 6) with 24-h urinary calcium excretion measured at baseline and after 2 hydrochlorothiazide doses (25 and ≥ 50 mg), there was a trend toward decreased urinary calcium excretion as the dose was increased from 25 to ≥ 50 mg/day (p = 0.051). Low-dose hydrochlorothiazide was often used for prevention of CCKS despite the fact that there is no evidence that it is effective in this setting. This may have resulted from a practice pattern of using lower doses for hypertension therapy or a lack of knowledge of RCT results in treatment of CCKS.
authors.affiliation: Department of Medicine, VA North Texas Heath Care System, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-8856, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Vigen
authors.forename: Rick A
authors.initials: RA
authors.lastname: Weideman
authors.forename: Robert F
authors.initials: RF
authors.lastname: Reilly
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D002752:Chlorthalidone / Q000008:administration & dosage* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D006852:Hydrochlorothiazide / Q000008:administration & dosage* / Q000627:therapeutic use; D007190:Indapamide / Q000008:administration & dosage* / Q000627:therapeutic use; D007669:Kidney Calculi / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D010818:Practice Patterns, Physicians'; D049993:Sodium Chloride Symporter Inhibitors / Q000008:administration & dosage* / Q000627:therapeutic use
chemical_list: D049993:Sodium Chloride Symporter Inhibitors; D006852:Hydrochlorothiazide; D007190:Indapamide; D002752:Chlorthalidone