Retrospective analysis of adverse drug reaction enquiries to a hospital drug information service: lessons to be learned to increase in-hospital drug safety

Objectives Adverse drug reactions (ADRs) are a major drug safety concern and a frequent topic of enquiries to hospital drug information services. Our goal was to analyse these enquiries regarding background, complexity, nature of ADR, and involved drug classes to improve in-hospital drug safety.Methods Retrospectively, ADR enquiries to a German university hospital pharmacy drug information 2018-2022 were analysed regarding enquirer (profession, medical specialty) and enquiry details (drugs, suspected ADR/enquiry prior to drug initiation, ADR system organ class, probable cause identified, and enquiry complexity).Key findings Of 543 enquiries, 516 (95%) were asked by physicians, 493 (91%) patient-specific, 390 (71%) on suspected ADRs, and 153 (28%) prior to drug initiation. Enquiries originated frequently from internal medicine (74/13.6%), paediatrics (71/13.1%), neurology (70/12.9%), and haemato-oncology (62/11.4%). Most frequent ADRs were haematologic (94/17%) and hepatic (72/13%). The median number of drugs per enquiry was three (range 0-37), 209 (38%) enquiries referred to one specific drug, 165 (30%) concerned >= 11 drugs. A probable cause for suspected ADRs was identified in 75 (36%) enquiries concerning one drug and 155 (94%) with >= 11 drugs. Most frequent drugs were antineoplastic (54/25.8%), nervous-system-drugs (42/20.1%), and anti-infective (40/19.1%). Most enquiries (342/63%) were complex (multiple/specialist resources).Conclusions Enquiries were usually asked by physicians referring to suspected ADRs in specific clinical situations. A probable cause was identified in many cases pointing to a direct positive impact on patient care. Enquiries prior to drug initiation should be encouraged to increase drug safety. Information on main ADR effects and drug classes helps with targeted counselling.