AimTo develop and test a new adverse drug reaction (ADR) causality assessment tool (CAT).MethodsA 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).ResultsThe 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’.ConclusionThe 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.

These data suggest that uNK cells may regulate angiogenesis in non-pregnant endometrium. The mechanisms of reproductive failure associated with increased uNK cell density appear to be increased angiogenesis and peri-implantation blood flow, which may lead to early maternal circulation and hence pregnancy failure due to excessive oxidative stress.

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