Adverse drug reaction and causality assessment scales

Sir, I read with interest the articles by Gupta et al and Gulati et al on adverse drug reactions of antituberculous drugs.[12] I would like to make the following comments. Adverse drug reactions (ADRs) are a major cause of morbidity, hospital admission, and even death. Hence it is essential to recognise ADRs and to establish a causal relationship between the drug and the adverse event. It is desirable that ADRs should be objectively assessed and presented based on an acceptable “Probability Scale.” Many causality methods have been proposed to assess the relationship between a drug and an adverse event in a given patient, ranging from short questionnaires to comprehensive algorithms. The idea of creating a standardized assessment for the relationship-likelihood of case reports of suspected ADRs was in the hope that this would, in a structured way, lead to a reliable reproducible measurement of causality. The causality assessment system proposed by the World Health Organization Collaborating Centre for International Drug Monitoring, the Uppsala Monitoring Centre (WHO–UMC), and the Naranjo Probability Scale are the generally accepted and most widely used methods for causality assessment in clinical practice as they offer a simple methodology.[34] The above scales are structured, transparent, consistent, and easy to apply assessment methods. Table 1 summarizes the “Naranjo ADR Probability Scale,” which has gained popularity among clinicians because of its simplicity.[3] The WHO–UMC causality system takes into account the clinical-pharmacologic aspects, whereas previous knowledge of the ADR plays a less prominent role. Table 2 summarizes the WHO–UMC Probability Scale.[4]Table 1: Naranjo ADR probability scale—items and scoreTable 2: WHO–UMC causality categoriesI humbly request the Editors that Lung India should use either of the above two scales while reviewing articles related to ADRs.