Abstract
BACKGROUND: Older adults are vulnerable to adverse drug reactions (ADRs) owing to physiological changes, comorbidities, and polypharmacy. Nationwide data on ADRs in older Korean adults are limited. This study aimed to describe the characteristics of ADRs and identify the risk factors for serious outcomes using the Korea Adverse Event Reporting System (KAERS). METHODS: We analyzed KAERS reports from 2005 to 2015. Eligible cases were patients aged ≥65 years with causality assessed as certain, probable, or possible for an orally administered drug. Serious ADRs were defined according to International Conference on Harmonization E2A and World Health Organization-Uppsala Monitoring Centre criteria. Descriptive statistics, chi-square tests, logistic regression, and disproportionality analyses were performed. RESULTS: Of the 889,997 ADR reports, 118,023 older patients met the inclusion criteria (mean age 73.6 years; 57.9% female). Frequent organ disorders included gastrointestinal, skin, and nervous system disorders. The common drug classes were analgesics, antimicrobials, and antituberculosis drugs. Overall, 6.1% of the cases were serious, mainly involving the hepatic and biliary systems, respiratory system, and bleeding/coagulopathy. The highest proportions of serious ADRs involved antineoplastic and antithrombotic agents. In multivariable analysis, male sex was independently associated with serious outcomes (adjusted odds ratio, 1.33; 95% confidence interval, 1.24-1.43), while age group was not. Disproportionality analysis identified notable drug-system organ class signals, including antimicrobials associated with application site disorders and antineoplastic agents associated with fetal disorders. CONCLUSION: Serious ADRs comprised 6.1% of reports in older Koreans. Antineoplastic and antithrombotic agents were strongly associated with serious outcomes and male sex was an independent risk factor. These findings underscore the need for safer prescriptions and improved pharmacovigilance for older patients.