Risk of thiazide-induced hyponatremia in patients with hypertension.
BACKGROUND
Although hyponatremia is a well-recognized complication of treatment with thiazide diuretics, the risk of thiazide-induced hyponatremia remains uncertain in routine care.


METHODS
We conducted a retrospective cohort study using a multicenter clinical research registry to identify 2613 adult outpatients that were newly treated for hypertension between January 1, 2000 and December 31, 2005 at 2 teaching hospitals in Boston, Massachusetts, and followed them for up to 10 years.


RESULTS
Two hundred twenty patients exposed to ongoing thiazide therapy were compared with 2393 patients who were not exposed. In the exposed group, 66 (30%) developed hyponatremia (sodium ≤130 mmol/L). The adjusted incidence rate of hyponatremia was 140 cases per 1000 person-years for patients treated with thiazides, compared with 87 cases per 1000 person-years in those without thiazides. Patients exposed to thiazides were more likely to develop hyponatremia (adjusted incidence rate ratio, 1.61; 95% confidence interval [CI], 1.15-2.25). There was no significant difference in the risk of hospitalizations associated with hyponatremia (adjusted rate ratio, 1.04; 95% CI, 0.46-2.32) or mortality (adjusted rate ratio, 0.41; 95% CI, 0.12-1.42). The number needed to harm (to result in one excess case of incident hyponatremia in 5 years) was 15.02 (95% CI, 7.88-160.30).


CONCLUSIONS
Approximately 3 in 10 patients exposed to thiazides who continue to take them develop hyponatremia.
Division of General Internal Medicine and Primary Care, Brigham & Women's Hospital, Boston, MA, USA.
Alexander A
AA
Leung
Adam
A
Wright
Valeria
V
Pazo
Andrew
A
Karson
David W
DW
Bates
D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000453:epidemiology; D007010:Hyponatremia / Q000139:chemically induced* / Q000453:epidemiology; D015994:Incidence; D008297:Male; D008404:Massachusetts; D008875:Middle Aged; D061366:Numbers Needed To Treat; D012189:Retrospective Studies; D012307:Risk Factors; D049993:Sodium Chloride Symporter Inhibitors / Q000009:adverse effects* / Q000627:therapeutic use
D049993:Sodium Chloride Symporter Inhibitors