title: Antiepileptic drugs and hyponatremia in older adults: Two population-based cohort studies.
abstract: To examine the 30-day risk of hospitalization with hyponatremia associated with carbamazepine, valproic acid (V), phenytoin (P), or topiramate (T) use compared to nonuse in the outpatient setting among older adults.
  
  
  
  We conducted two population-based, retrospective cohort studies in Ontario, Canada, between 2003 and 2015 using administrative health care databases of older adults. The first study compared carbamazepine users to a propensity-score matched group of antiepileptic drug nonusers, whereas the second compared V-P-T users to a propensity-score matched group of antiepileptic nonusers. The primary outcome was hospitalization with hyponatremia within 30 days of an antiepileptic prescription.
  
  
  
  The baseline characteristics between matched groups were similar in both cohorts. Carbamazepine use versus nonuse was associated with a higher 30-day risk of hospitalization with hyponatremia (82/21,191 [0.39%] versus 30/63,573 [0.05%]; relative risk [RR] 8.20, 95% confidence interval [CI] 5.40-12.46). Similarly, V-P-T use versus nonuse was associated with a higher 30-day risk of hospitalization with hyponatremia (34/20,155 [0.17%] versus 26/40,310 [0.06%]; RR 2.62, 95% CI 1.57-4.36).
  
  
  
  Older adults prescribed carbamazepine and V-P-T have a higher risk of being hospitalized with hyponatremia compared to other adults with similar indicators of baseline health who were not prescribed antiepileptic drugs. Physicians should be mindful of this risk; when a patient presents to a hospital with symptomatic hyponatremia these drugs should be considered as potential causes.
authors.affiliation: Department of Epidemiology & Biostatistics, Western University, London, Ontario, Canada.|Division of Nephrology, Department of Medicine, Western University, London, Ontario, Canada.
authors.forename: Sonja
authors.initials: S
authors.lastname: Gandhi
authors.affiliation: Division of Nephrology, Department of Medicine, Western University, London, Ontario, Canada.|Institute for Clinical Evaluative Sciences, London, Ontario, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: McArthur
authors.affiliation: Institute for Clinical Evaluative Sciences, London, Ontario, Canada.|Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: Muhammad M
authors.initials: MM
authors.lastname: Mamdani
authors.affiliation: Institute for Clinical Evaluative Sciences, London, Ontario, Canada.|Division of Clinical Pharmacology, Department of Medicine, Western University, London, Ontario, Canada.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Hackam
authors.affiliation: Epilepsy Program, Department of Clinical Neurological Sciences, Western University, London, Ontario, Canada.
authors.forename: Richard S
authors.initials: RS
authors.lastname: McLachlan
authors.affiliation: Department of Epidemiology & Biostatistics, Western University, London, Ontario, Canada.|Division of Nephrology, Department of Medicine, Western University, London, Ontario, Canada.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Weir
authors.affiliation: Institute for Clinical Evaluative Sciences, London, Ontario, Canada.|Epilepsy Program, Department of Clinical Neurological Sciences, Western University, London, Ontario, Canada.
authors.forename: Jorge G
authors.initials: JG
authors.lastname: Burneo
authors.affiliation: Department of Epidemiology & Biostatistics, Western University, London, Ontario, Canada.|Division of Nephrology, Department of Medicine, Western University, London, Ontario, Canada.|Institute for Clinical Evaluative Sciences, London, Ontario, Canada.
authors.forename: Amit X
authors.initials: AX
authors.lastname: Garg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000927:Anticonvulsants / Q000009:adverse effects*; D002220:Carbamazepine / Q000009:adverse effects*; D015331:Cohort Studies; D018672:Community Health Planning; D016208:Databases, Factual / Q000706:statistics & numerical data; D004827:Epilepsy / Q000188:drug therapy; D005260:Female; D006760:Hospitalization; D006801:Humans; D007010:Hyponatremia / Q000139:chemically induced*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged
chemical_list: D000927:Anticonvulsants; D002220:Carbamazepine
keywords: Adverse drug event; Antiepileptic drugs; Hyponatremia