Adverse drug event detection in Latvian administrative data

Abstract

Health risks of medicines in clinical practice often differ from trial data, making adverse drug event (ADE) monitoring essential for post-marketing surveillance. In Latvia, ADE reporting is available but remains low, indicating substantial underreporting. This study aimed to identify unreported ADE cases in administrative data and evaluate whether their occurrence exceeds reports in the State Agency of Medicines (SAM) system more than twofold. Data covered 1 January 2016 – 31 December 2020, and included passive ADE reports from SAM and anonymised inpatient and outpatient records from the Latvian Centre for Disease Prevention and Control (CDPC). Diagnostic code sets were applied: the original (Hohl et al., 2013) with 375 ADE codes, and a narrowed, author-adapted Latvian dataset with 165 codes. Diagnoses were classified as A1 (medicine-related) or A2 (medicine/other substance-related). A total of 15,638 unique inpatient and outpatient reports were analysed. The Latvian dataset outperformed the original, with CDPC data detecting ADE cases 9–31 times more frequently than SAM. The A1 group identified 10–30% of potential ADEs and mirrored SAM dynamics, suggesting greater effectiveness than A2. Findings indicate that diagnostic coding can complement passive systems, enabling more effective post-marketing surveillance.