Comparison of the Naranjo and WHO-Uppsala Monitoring Centre criteria for causality assessment of adverse drug reactions

Son, Myoung Kyun; Lee, Yong Won; Jung, Han Young; Yi, Seung Woo; Lee, Kwang Hoon; Kim, Seung Up; Jeong, Jae Heon; Park, Jae Jun; Park, Jung Won; Hong, Chein Soo

Abstract

BACKGROUND/AIMS: Several criteria have been proposed to increase the objectivity, reliability and validity of causality assessment of adverse drug reactions (ADR). We compared the Naranjo probability scale and the World Health Organization-Uppsala Monitoring Centre (WHO-UMC) causality categories to evaluate the validity and clinical usefulness of these criteria.
METHODS
We evaluated 100 ADR cases with the Naranjo probability scale and the WHO-UMC causality categories. The Spearman rank coefficient was used to determine the correlation of these criteria. The evaluation of the ADR was categorized into four groups for the Naranjo system: definite, probable, possible, and doubtful, and six groups for the WHO UMC: certain, probable, possible, unlikely, conditional/unclassified, and unassessable.
RESULTS
The criteria used form these two systems showed some differences when compared with the same ADR cases. The Spearman rank coefficient was 0.519 (p<0.001) and the agreement was 55% between the Naranjo probability scale and the WHO-UMC causality categories. The Naranjo probability scale includes measurements for drug concentration, objective evidence of ADR, ADR to previous exposures, responses to placebo, and the dose adjustment of drugs. However, few cases were evaluated for all of these measures.
CONCLUSIONS
The Naranjo probability scale may be helpful for assessing unexpected ADRs and useful for evaluators with little experience. However, some of the items are not utilized and there are discrepancies when compared with the WHO-UMC causality criteria.