title: Abstracts and papers published in the International Journal of Obstetric Anesthesia since inception.
abstract: BACKGROUND
  Since the International Journal of Obstetric Anesthesia (IJOA) was first published in 1991, barriers to conducting and publishing research in the UK have increased, as has the pressure to improve practitioners' curricula vitae. We speculated that the type and geographical origin of abstracts and papers published in IJOA might reflect these changes.
  
  
  METHODS
  We analysed all substantive papers and Obstetric Anaesthetists' Association abstracts published in IJOA, using online access. Full articles and abstracts were categorised and the location of the submitting hospital recorded. Those published in the period 1991-99 inclusive were compared with those in 2000-08.
  
  
  RESULTS
  A total of 890 substantive papers were reviewed, 387 in 1991-99 and 503 in 2000-08. We found non-significant changes (P = 0.065) in the type of paper between the two time periods; the number (proportion) of observational studies increased from 178 (46%) to 256 (51%), respectively, while randomised and non-randomised interventional trials remained similar. Changes in geographical origin were also not significant (P = 0.17), with most coming from the UK and outside Europe. Non-UK European papers accounted for only 54 (14%) and 65 (13%), respectively. Abstract numbers have increased greatly, from 190 in 1991-99 to 702 in 2000-08, with increases in all categories but a doubling of the proportion of observational studies and a reduced proportion of interventional trials: observational 17% and 34% respectively; randomised 23% and 13% respectively; and non-randomised interventional 29% and 26% respectively (P < 0.0001). Most abstracts were from the UK although this proportion fell from 92% in 1991-99 to 86% in 2000-08, whilst those from non-UK European countries and the rest of the world increased (respectively 2% and 6% in 1991-99; 7% and 8% in 2000-08; P = 0.001).
  
  
  CONCLUSIONS
  Substantive papers and abstracts show different trends but observational studies are the most frequent type in both forms of presentation. Trends in abstracts suggest a decrease in the proportion of randomised controlled trials, although the absolute numbers of interventional trials has increased. Non-UK European papers and abstracts are relatively few compared with those from the UK and rest of the world.
authors.affiliation: Magill Department of Anaesthesia, Intensive Care & Pain Management, Chelsea and Westminster Hospital, London, UK. guy.jackson@royalberkshire.nhs.uk
authors.forename: G N B
authors.initials: GN
authors.lastname: Jackson
authors.forename: M J
authors.initials: MJ
authors.lastname: Mackenzie
authors.forename: L A
authors.initials: LA
authors.lastname: Arrandale
authors.forename: S M
authors.initials: SM
authors.lastname: Yentis
mesh_terms: D000773:Anesthesia, Obstetrical / Q000706:statistics & numerical data*; D015706:Bibliometrics; D010506:Periodicals as Topic / Q000706:statistics & numerical data* / Q000639:trends; D016032:Randomized Controlled Trials as Topic