Comparative analysis of the characteristics and trends of adverse drug reaction reports from patients in Japan and the Japanese Adverse Drug Event Report database.

aimsSpontaneous reporting of adverse drug reactions (ADR) after a product has reached the market is essential for drug safety. This study analysed patient ADR reports and compared them with reports from the Japanese Adverse Drug Event Report (JADER) database to identify differences and trends.

methodsADR reports from the Pharmaceuticals and Medical Devices Agency website, including patient reports from March 2019 to March 2024, and JADER reports from January 2019 to March 2024, were utilized. Information on demographics, drugs, ADR types and outcomes was analysed. Frequencies and comparisons between the two reporting groups were performed.

resultsA total of 2913 patient reports and 343 894 JADER reports were analysed. Patients were often younger (30-50 years) and mostly female, whereas JADER reports included older patients (60-80 years) and mostly male. Patients reported subjective symptoms, such as fatigue and headache, often associated with drugs targeting the central nervous system. In contrast, JADER reports focused on serious conditions, such as interstitial lung disease and pneumonia, which are commonly associated with anticancer drugs. Patient and professional ADR reports differed in focus. Patients highlighted quality-of-life-related symptoms, whereas professionals reported more serious medical conditions. Differences in demographics and reporting methods indicate that these systems are complementary. Offering more reporting options, such as telephone-based submissions, can make the system more inclusive.

conclusionsThe study highlights how patient ADR reports provide valuable insights into drug safety. Although differences exist, patient and professional reports improve monitoring after drug approval.