Strategies and Challenges in Coding Ambiguous Information Using MedDRA®: An Exploration Among Norwegian Pharmacovigilance Officers

Introduction The Medical Dictionary for Regulatory Activities (MedDRA®) is an international standardized medical terminology used to code various types of medical information, including safety reports of suspected adverse reactions to medicines. Quantitative studies have highlighted varying levels of coding inconsistency across MedDRA®-relevant platforms, though the possible grounds of such inconsistency remain unclear. Objective We explored the reasoning and strategies employed by pharmacovigilance officers when coding selected ambiguous adverse events to MedDRA®, categorized the types of coding inconsistencies, and explored sources of the inconsistencies. Methods Pharmacovigilance officers from the Norwegian public health sector were invited to participate in a survey-based, cross-sectional study followed by focus group interviews. The survey consisted of 11 coding tasks, with varying degrees of ambiguity, purposively sampled from the Norwegian pharmacovigilance registry. Participants selected the appropriate MedDRA® terms and graded the difficulty level of each task on a scale from 1 (least difficult) to 4 (most difficult). Terms selected by participants were compared with a Standard Term Selection (STS), agreed upon by the authors in consultation with a MedDRA® trainer. Inconsistencies with the STS were classified as omission (missing term), substitution (extra term selected in the presence of an omission), and addition (extra term selected and none omitted). In focus groups, participants discussed challenges in the coding tasks and the strategies they used to overcome them. Interview transcripts were analyzed using thematic analysis. Results In total, 26 coders (79% of the eligible population) completed the survey. Of the survey answers, 36% were identical to the STS; answers consistent with the STS varied across the specific coding tasks and did not align with the perceived difficulty of the tasks. The most common inconsistency (30% of the survey answers) arose from substituting one of multiple MedDRA® terms. Of the survey answers, 18% included omissions without substitutions, and 6% added unnecessary terms to the STS. Eight of the 26 coders (31%) participated in the focus group interviews. Focus group themes revealed that substitutions were explained by difficulties in translating lay language to medical terminology, finding accurate English translations for Norwegian medical terms, and fitting complex descriptions into MedDRA® terms. This was explained by themes related to ambiguity-resolution strategies. Themes explaining omissions included strategies for resolving ambiguity, contextual thinking, causal and pharmacological reasoning in the coding process, and information categorization. Conclusions Tailored training programs and clear institutional guidelines are needed to target the sources of coding inconsistencies suggested by this study.