title: Determinants of signal selection in a spontaneous reporting system for adverse drug reactions.
abstract: OBJECTIVE
  Detection of new adverse drug reactions (ADR) after marketing is often based on a manual review of reports sent to a Spontaneous Reporting System (SRS). Among the many potential signals that are identified, only a limited number are important enough to require further attention. The goal of this study is to gain insight into factors contributing to the selection and dissemination of possible signals originating from the SRS maintained by the Netherlands Pharmacovigilance Foundation.
  
  
  METHODS
  In a case control design, all signals (n = 42) disseminated to the Medicines Evaluation Board from the second quarter of 1997 until the third quarter of 2000, which could be expressed as a combination of a single ATC code and a single WHO preferred term, were included. For each case, four controls were matched in time. Logistic regression analysis was used to investigate the influence of various factors, such as the fact whether the ADR or drug is new, the strength of the association, the seriousness of the reaction and the documentation of the reports.
  
  
  RESULTS
  Multivariate analysis showed that the presence of a 'serious report' (Odds Ratio 3.8, 95% CI 1.3, 11.0), a WHO 'critical term' (OR 4.7, 95% CI 1.8, 13), the ADR being unlabelled (OR 6.1, 95% CI 2.3, 16) and the presence of a disproportionate association (OR 3.5, 95% CI 1.4, 8) were all independently associated with signal selection. The number of reports and the time after marketing of the drug had no influence.
  
  
  CONCLUSIONS
  This study showed that selection of signals is based on both qualitative and quantitative aspects. Knowledge of these factors may improve the efficiency of the underlying signal selection process.
authors.affiliation: Netherlands Pharmacovigilance Foundation Lareb, 's-Hertogenbosch, The Netherlands. e.vanpuijenbroek@lareb.nl
authors.forename: E P
authors.initials: EP
authors.lastname: van Puijenbroek
authors.forename: K
authors.initials: K
authors.lastname: van Grootheest
authors.forename: W L
authors.initials: WL
authors.lastname: Diemont
authors.forename: H G
authors.initials: HG
authors.lastname: Leufkens
authors.forename: A C
authors.initials: AC
authors.lastname: Egberts
mesh_terms: D016907:Adverse Drug Reaction Reporting Systems / Q000295:instrumentation / Q000706:statistics & numerical data*; D016022:Case-Control Studies; D004347:Drug Interactions; D006801:Humans; D015999:Multivariate Analysis; D009426:Netherlands; D016017:Odds Ratio; D012044:Regression Analysis; D014944:World Health Organization