title: Altered mental status in older adults with histamine2-receptor antagonists: a population-based study.
abstract: BACKGROUND
  Standard doses of histamine2-receptor antagonists (H2RAs) may induce altered mental status in older adults, especially in those with chronic kidney disease (CKD).
  
  
  METHODS
  Population-based cohort study of older adults who started a new H2RA between 2002 and 2011 was conducted. Ninety percent received the current standard H2RA dose in routine care. There was no significant difference in 27 baseline patient characteristics. The primary outcome was hospitalization with an urgent head computed tomography (CT) scan (proxy for altered mental status), and the secondary outcome was all-cause mortality also within 30days of a new H2RA prescription.
  
  
  RESULTS
  Standard vs. low H2RA dose was associated with a higher risk of hospitalization with an urgent head CT scan (0.98% vs. 0.74%, absolute risk difference 0.24% [95% CI 0.11% to 0.36%], relative risk 1.33 [95% CI 1.12 to 1.58]). This risk was not modified by the presence of CKD (interaction P value=0.71). Standard vs. low H2RA dose was associated with a higher risk of mortality (1.07% vs.0.74%; absolute risk difference 0.34% [95% CI 0.20% to 0.46%], relative risk 1.46 [95% CI 1.23 to 1.73]).
  
  
  CONCLUSIONS
  Compared to a lower dose, initiation of the current standard dose of H2RA in older adults is associated with a small absolute increase in the 30-day risk of altered mental status (using neuroimaging as a proxy), even in the absence of CKD. This risk may be avoided by initiating older adults on low doses of H2RAs for gastroesophogeal reflux disease, and increasing dosing as necessary for symptom control.
authors.affiliation: Schulich School of Medicine, Western University, London, Canada; Division of Nephrology, Western University, London, Ontario, Canada.
authors.forename: Davy
authors.initials: D
authors.lastname: Tawadrous
authors.affiliation: Schulich School of Medicine, Western University, London, Canada; Division of Nephrology, Western University, London, Ontario, Canada; Department of Epidemiology and Biostatistics, Western University, London, Ontario, Canada; Institute for Clinical Evaluative Sciences, Ontario, Canada.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Dixon
authors.affiliation: Schulich School of Medicine, Western University, London, Canada; Institute for Clinical Evaluative Sciences, Ontario, Canada.
authors.forename: Salimah Z
authors.initials: SZ
authors.lastname: Shariff
authors.affiliation: Division of Nephrology, Western University, London, Ontario, Canada.
authors.forename: Jamie
authors.initials: J
authors.lastname: Fleet
authors.affiliation: Schulich School of Medicine, Western University, London, Canada; Division of Nephrology, Western University, London, Ontario, Canada; Department of Epidemiology and Biostatistics, Western University, London, Ontario, Canada.
authors.forename: Sonja
authors.initials: S
authors.lastname: Gandhi
authors.affiliation: Schulich School of Medicine, Western University, London, Canada; Division of Nephrology, Western University, London, Ontario, Canada; Department of Epidemiology and Biostatistics, Western University, London, Ontario, Canada.
authors.forename: Arsh K
authors.initials: AK
authors.lastname: Jain
authors.affiliation: Schulich School of Medicine, Western University, London, Canada; Division of Nephrology, Western University, London, Ontario, Canada; Department of Epidemiology and Biostatistics, Western University, London, Ontario, Canada.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Weir
authors.affiliation: Institute for Clinical Evaluative Sciences, Ontario, Canada; Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; Keenan Research Centre, Li Ka Shing Knowledge Institute, Toronto, Ontario, Canada.
authors.forename: Tara
authors.initials: T
authors.lastname: Gomes
authors.affiliation: Schulich School of Medicine, Western University, London, Canada; Division of Nephrology, Western University, London, Ontario, Canada; Department of Epidemiology and Biostatistics, Western University, London, Ontario, Canada; Institute for Clinical Evaluative Sciences, Ontario, Canada. Electronic address: amit.garg@lhsc.on.ca.
authors.forename: Amit X
authors.initials: AX
authors.lastname: Garg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000139:chemically induced*; D003693:Delirium / Q000139:chemically induced* / Q000453:epidemiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005919:Glomerular Filtration Rate; D006257:Head / Q000000981:diagnostic imaging; D006635:Histamine H2 Antagonists / Q000008:administration & dosage / Q000009:adverse effects*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed
chemical_list: D006635:Histamine H2 Antagonists
keywords: Aged; Altered mental status; Chronic renal insufficiency; Cohort studies; Histamine H2 antagonists; Risk