title: Gross Domestic Product (GDP) and productivity of schizophrenia trials: an ecological study.
abstract: BACKGROUND
  The 5000 randomised controlled trials (RCTs) in the Cochrane Schizophrenia Group's database affords an opportunity to research for variables related to the differences between nations of their output of schizophrenia trials.
  
  
  METHODS
  Ecological study--investigating the relationship between four economic/demographic variables and number of schizophrenia RCTs per country. The variable with closest correlation was used to predict the expected number of studies.
  
  
  RESULTS
  GDP closely correlated with schizophrenia trial output, with 76% of the total variation about the Y explained by the regression line (r = 0.87, 95% CI 0.79 to 0.92, r2 = 0.76). Many countries have a strong tradition of schizophrenia trials, exceeding their predicted output. All nations with no identified trial output had GDPs that predicted zero trial activity. Several nations with relatively small GDPs are, nevertheless, highly productive of trials. Some wealthy countries seem either not to have produced the expected number of randomised trials or not to have disseminated them to the English-speaking world.
  
  
  CONCLUSIONS
  This hypothesis-generating study could not investigate causal relationships, but suggests, that for those seeking all relevant studies, expending effort searching the scientific literature of Germany, Italy, France, Brazil and Japan may be a good investment.
authors.affiliation: Schule fuer Medizinische Dokumentation, Universitaetklinikum Ulm, Academie fuer Medizinische Berufe, Ulm, 89070, Germany. carenina@gmx.net
authors.forename: Carina
authors.initials: C
authors.lastname: Moll
authors.forename: Ursula
authors.initials: U
authors.lastname: Gessler
authors.forename: Stephanie
authors.initials: S
authors.lastname: Bartsch
authors.forename: Hany George
authors.initials: HG
authors.lastname: El-Sayeh
authors.forename: Mark
authors.initials: M
authors.lastname: Fenton
authors.forename: Clive Elliott
authors.initials: CE
authors.lastname: Adams
mesh_terms: D003431:Cross-Cultural Comparison; D019992:Databases as Topic / Q000706:statistics & numerical data; D004467:Economics / Q000706:statistics & numerical data*; D004526:Efficiency; D006801:Humans; D033181:Information Dissemination; D007255:Information Services / Q000592:standards / Q000706:statistics & numerical data; D016014:Linear Models; D011336:Probability; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D012559:Schizophrenia / Q000188:drug therapy*; D012959:Socioeconomic Factors; D012984:Software / Q000706:statistics & numerical data