title: Association between consistent purchase of anticonvulsants or lithium and suicide risk: a longitudinal cohort study from Denmark, 1995-2001.
abstract: BACKGROUND
  Prior studies suggest anticonvulsants purchasers may be at greater risk of suicide than lithium purchasers.
  
  
  METHODS
  Longitudinal, retrospective cohort study of all individuals in Denmark purchasing anticonvulsants (valproic acid, carbamazepine, oxcarbazepine or lamotrigine) (n=9952) or lithium (n=6693) from 1995-2001 who also purchased antipsychotics at least once (to select out nonpsychiatric anticonvulsant use). Poisson regression of suicides by medication purchased (anticonvulsants or lithium) was conducted, controlling for age, sex, and calendar year. Confounding by indication was addressed by restricting the comparison to individuals prescribed the same medication: individuals with minimal medication exposure (e.g., who purchased only a single prescription of anticonvulsants) were compared to those individuals with more consistent medication exposure (i.e., purchasing > or = 6 prescriptions of anticonvulsants).
  
  
  RESULTS
  Demographics and frequency of anticonvulsant, lithium, or antipsychotic use were similar between lithium and anticonvulsant purchasers. Among patients who also purchased antipsychotic at least once during the study period, purchasing anticonvulsants more consistently (> or = 6 prescriptions) was associated with a substantial reduction in the risk of suicide (RR=0.22, 95% CI=0.11-0.42, p<0.0001), similar to patients consistently purchasing lithium (RR=0.27, 95% CI=0.12-0.62, p=0.006). Absolute suicide risks of consistent anticonvulsant and consistent lithium purchasers were similar.
  
  
  CONCLUSIONS
  Lack of information about diagnoses and potential confounders, as well as other covariates that may differ between minimal and consistent medication purchasers, are limitations to this study.
  
  
  CONCLUSIONS
  In this longitudinal study of anticonvulsant purchasers likely to have psychiatric disorders, consistent anticonvulsant treatment was associated with decreased risk of completed suicide.
authors.affiliation: Center for Psychopharmacologic Research and Treatment, Department of Psychiatry, University of Massachusetts Medical School, Worcester, MA 01605, USA. 610041,
authors.forename: Eric G
authors.initials: EG
authors.lastname: Smith
authors.forename: Lars
authors.initials: L
authors.lastname: Søndergård
authors.forename: Ana Garcia
authors.initials: AG
authors.lastname: Lopez
authors.forename: Per Kragh
authors.initials: PK
authors.lastname: Andersen
authors.forename: Lars Vedel
authors.initials: LV
authors.lastname: Kessing
mesh_terms: D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000009:adverse effects / Q000627:therapeutic use*; D018692:Antimanic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000627:therapeutic use; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003718:Denmark; D005260:Female; D006801:Humans; D015994:Incidence; D016651:Lithium Carbonate / Q000009:adverse effects / Q000627:therapeutic use*; D008134:Long-Term Care; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018570:Risk Assessment; D013405:Suicide / Q000706:statistics & numerical data*; D000092864:Suicide Prevention
chemical_list: D000927:Anticonvulsants; D018692:Antimanic Agents; D014150:Antipsychotic Agents; D016651:Lithium Carbonate