Introduction
The causality assessment of adverse drug reactions (ADR) is an essential
approach in pharmacovigilance, as an attempt to investigate the
connection between the use of a drug and a suspected ADR. WHO-UMC system
is a universally used method for causality assessment.[1] Previous
data emphasized its high consistency to be applied in hospitalized
patients. However, there are some limitations raised by some authors
regarding the fact that it is based on individual knowledge and
judgment, and a poor reproducibility has been encountered among
different judges.[1, 2] Naranjo algorithm is another method used to
assess ADR causality which has been reported to be simple and brief.
This is widely used due to its easy implementation and high interrater
agreement, despite poor sensitivity.[1-4]
Causality assessment presupposes theoretical-methodological integration,
but requires judgments which are essential for drug safety
evaluation.[4] Adequate categorization of causality, especially in
highly complex institutions, may contribute to the early recognition of
ADR and their consequent prevention, in addition to the optimization of
drug therapy.[3] We sought to assess causality of ADR in patients
hospitalized in a university hospital, using the WHO-UMC method, to
evaluate the performance of Naranjo algorithm[5] and ADR
preventability using an adapted Schumock and Thornton method.[6, 7]