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Updated: May 26, 2026

Human Liver Microphysiological System for Assessing Drug-Induced Liver Toxicity In Vitro
Published on: January 31, 2022
Development and inter-rater reliability of the Liverpool adverse drug reaction causality assessment tool
Ruairi M Gallagher1, Jamie J Kirkham, Jennifer R Mason
1Institute of Child Health, Department of Women's and Children's Health, University of Liverpool, Liverpool, United Kingdom.
Aim:
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).
Main Outcome Measures:
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'.
Conclusion:
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.
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