Comparative Analysis of Drugs Frequently Suspected of Causing Adverse Drug Reactions Reported via the Spontaneous Reporting System Versus in a Prospective Multicentre Cohort Study in Hospital Emergency Departments

<b>Background/Objectives</b>: Pharmacovigilance aims to identify, assess, and minimize drug risks, with spontaneous reporting playing a central role. However, the high level of underreporting and the varying data quality are limitations that should be minimized through prospective cohort studies. <b>Methods</b>: Spontaneous reports reported to the Drug Commission of the German Medical Association (AkdÄ) over one year were compared with the adverse drug reaction (ADR) cases systematically recorded in hospital emergency departments. The frequencies of the demographic patient characteristics and the odds ratios, as the relationship between suspected and concomitant medication, were calculated. <b>Results</b>: In the spontaneous reports, cases were reported by patients a median of 12 years younger, and the group of older patients was less represented (10.8% versus 27.3% in the prospective cohort study). Within the study, cases with polypharmacy were documented significantly more often (a median of seven drugs [IQR 3;10] versus a median of two drugs [IQR 1;5] in the spontaneous reports). New drugs and drugs discussed in the media were frequently reported as causing ADRs, whereas drugs with an effect on the central nervous system were more often suspected in the emergency department setting. <b>Conclusions</b>: Both sources for ADRs provide complementary information that improves the detection of risk signals. The aim for the future is to further increase the awareness of spontaneous reports and to answer specific questions with the help of structured investigations. It is important to compare and validate the findings of spontaneous reports and investigations in regular intervals to improve drug safety.