Development and validation of standardized severity rating scale to assess the consistency of drug-drug interaction severity among various drug information resources

Abstract

Background: The consistency in reporting the severity of drug interactions across the drug information resources is important in guiding the appropriate clinical use of drug-pairs, to minimize the associated adverse events. This necessitates the need of a standardized severity rating scale, that can accommodate the different severity ratings of the same interacting drug-pair into a reasonable severity category, that can ease the consistency assessment among different drug information resources.

Objective: To develop and validate a standardized severity rating scale that can ease the consistency assessment among the various drug information resources.

Methods: The definitions of various severity rating categories as documented in the eight drug information resources was consolidated to develop a standardized severity rating scale. Thus developed rating scale was validated using twenty commonly used drug-pairs. Fleiss' kappa score was used as an indicator for assessing overall consistency among various drug information resources, whereas, Cohen's kappa was used as an indicator of level of consistency between two drug information resources and between individual drug information resource and newly developed standardized severity rating scale.

Results: The newly developed standardized severity rating scale classifies the severity of drug-drug interactions into three categories namely mild, moderate and major. The Fleiss' kappa score was improved from 0.047 to 0.176, indicating improved strength of agreement [Average pairwise agreement: 16% Vs 36.7%] among various drug information resources. The average pairwise Cohen's kappa was 0.082 [Strength of agreement: poor] in original severity ratings whereas it was improved to 0.198 [Strength of agreement: almost equal to fair] in standardized severity rating scale.

Conclusion: The newly developed standardized severity rating scale can be used as a tool to assess the consistency of severity rating categories among the various drug information resources.

Keywords: Adverse events; Consistency assessment; Drug information resources; Drug interaction severity; Drug-drug interactions; Severity rating scale.