title: Prevalence and risk of thrombocytopenia with valproic acid: experience at a psychiatric teaching hospital.
abstract: OBJECTIVE
  To investigate the prevalence and potential risk factors of thrombocytopenia in hospitalized patients receiving valproic acid (VPA) for psychiatric indications (excluding epilepsy).
  
  
  METHODS
  Retrospective study
  
  
  METHODS
  University-affiliated psychiatric facility.
  
  
  METHODS
  Two hundred sixty-four patients treated with VPA.
  
  
  METHODS
  Data from patients hospitalized between January 1, 1994, and December 31, 1998, who were receiving VPA and had at least one platelet count recorded.
  
  
  RESULTS
  Of 264 VPA-treated patients, 31 (12%) met our criteria for thrombocytopenia. Mild thrombocytopenia (platelet count of 101-150 x 10(3)/mm3) occurred in 25 (9%) patients, and moderate thrombocytopenia (platelet count of 40-100 x 103/mm3) occurred in 6 (2%) patients. Age older than 65 years (p=0.02) and VPA dosage greater than 1,000 mg/day (p<0.001) were identified as significant risk factors for developing thrombocytopenia.
  
  
  CONCLUSIONS
  The estimated prevalence of thrombocytopenia is 12% in the general psychiatric population receiving VPA, with the elderly at greatest risk.
authors.affiliation: School of Pharmacy, University of Pittsburgh, PA 16261, USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Conley
authors.forename: K C
authors.initials: KC
authors.lastname: Coley
authors.forename: B G
authors.initials: BG
authors.lastname: Pollock
authors.forename: S V
authors.initials: SV
authors.lastname: Dapos
authors.forename: R
authors.initials: R
authors.lastname: Maxwell
authors.forename: R A
authors.initials: RA
authors.lastname: Branch
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D018692:Antimanic Agents / Q000009:adverse effects*; D016009:Chi-Square Distribution; D004305:Dose-Response Relationship, Drug; D006778:Hospitals, Psychiatric / Q000706:statistics & numerical data; D006784:Hospitals, Teaching / Q000706:statistics & numerical data; D006801:Humans; D008875:Middle Aged; D010976:Platelet Count / Q000706:statistics & numerical data; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced* / Q000453:epidemiology*; D014635:Valproic Acid / Q000009:adverse effects*
chemical_list: D018692:Antimanic Agents; D014635:Valproic Acid