title: Development and inter-rater reliability of the Liverpool adverse drug reaction causality assessment tool.
abstract: OBJECTIVE
  To develop and test a new adverse drug reaction (ADR) causality assessment tool (CAT).
  
  
  METHODS
  A comparison between seven assessors of a new CAT, formulated by an expert focus group, compared with the Naranjo CAT in 80 cases from a prospective observational study and 37 published ADR case reports (819 causality assessments in total).
  
  
  METHODS
  Utilisation of causality categories, measure of disagreements, inter-rater reliability (IRR).
  
  
  RESULTS
  The Liverpool ADR CAT, using 40 cases from an observational study, showed causality categories of 1 unlikely, 62 possible, 92 probable and 125 definite (1, 62, 92, 125) and 'moderate' IRR (kappa 0.48), compared to Naranjo (0, 100, 172, 8) with 'moderate' IRR (kappa 0.45). In a further 40 cases, the Liverpool tool (0, 66, 81, 133) showed 'good' IRR (kappa 0.6) while Naranjo (1, 90, 185, 4) remained 'moderate'.
  
  
  CONCLUSIONS
  The Liverpool tool assigns the full range of causality categories and shows good IRR. Further assessment by different investigators in different settings is needed to fully assess the utility of this tool.
authors.affiliation: Institute of Child Health, Department of Women's and Children's Health, University of Liverpool, Liverpool, United Kingdom.
authors.forename: Ruairi M
authors.initials: RM
authors.lastname: Gallagher
authors.forename: Jamie J
authors.initials: JJ
authors.lastname: Kirkham
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Mason
authors.forename: Kim A
authors.initials: KA
authors.lastname: Bird
authors.forename: Paula R
authors.initials: PR
authors.lastname: Williamson
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Nunn
authors.forename: Mark A
authors.initials: MA
authors.lastname: Turner
authors.forename: Rosalind L
authors.initials: RL
authors.lastname: Smyth
authors.forename: Munir
authors.initials: M
authors.lastname: Pirmohamed
mesh_terms: D016907:Adverse Drug Reaction Reporting Systems / Q000592:standards*; D015984:Causality; D003657:Decision Making; D006801:Humans; D015588:Observer Variation; D015203:Reproducibility of Results