title: Sex differences in cerebral venous thrombosis: A systematic analysis of a shift over time.
abstract: BACKGROUND
  In contemporary studies, cerebral venous thrombosis is three times more common in adult women than in men.
  
  
  OBJECTIVE
  To study the change in sex ratio over time in cerebral venous thrombosis.
  
  
  RESULTS
  We systematically reviewed the literature. Any type of study with at least 40 patients with cerebral venous thrombosis that reported sex ratio was eligible. We ranked studies according to the year halfway the period of patient recruitment. Pediatric studies were analyzed separately. Out of 6068 publications identified by our search, 112 studies (23,638 patients), published between 1966 and 2014, were included. The proportion of women among patients with cerebral venous thrombosis significantly increased over time from a median of 54.8% in studies prior to 1981 to 69.8% after 2001 (p = 0.002). There was a significant correlation between time of the study and proportion of women (Pearson's correlation coefficient 0.25, p = 0.01). Oral contraceptive use among women with cerebral venous thrombosis also increased over time (Pearson's correlation coefficient 0.29, p = 0.01). In contrast, the percentage of pregnancy-related cases remained stable (Pearson's correlation coefficient 0.04, p = 0.77). Among 1702 patients from pediatric studies, 39% were female and there was no correlation between sex ratio and time of the study (Pearson's correlation coefficient -0.42, p = 0.14).
  
  
  CONCLUSIONS
  In adult patients with cerebral venous thrombosis, there is a shift in sex ratio over time with an increase in the proportion of women, whereas this is not observed in pediatric populations. A possible explanation for this phenomenon is an increase over time in the use of oral contraceptives by adult women.
authors.affiliation: Department of Neurology, Academic Medical Centre, Amsterdam, The Netherlands j.coutinho@amc.nl.
authors.forename: Susanna M
authors.initials: SM
authors.lastname: Zuurbier
authors.affiliation: Department of Vascular Medicine, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Saskia
authors.initials: S
authors.lastname: Middeldorp
authors.affiliation: Department of Neurology, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Stam
authors.affiliation: Department of Neurology, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Coutinho
mesh_terms: D003276:Contraceptives, Oral / Q000627:therapeutic use; D006801:Humans; D020767:Intracranial Thrombosis / Q000453:epidemiology*; D012727:Sex Characteristics; D012744:Sex Ratio; D013997:Time Factors; D020246:Venous Thrombosis / Q000453:epidemiology*
chemical_list: D003276:Contraceptives, Oral
keywords: Oral contraceptives; neurology; risk factors; stroke; stroke subtypes; venous thrombosis