Background Specific studies focusing exclusively on ADEs show different values in incidence and nature of the reported events. Evidence from general adverse events studies has never been analysed in Spain.

Purpose To evaluate the ADEs identified in two Spanish Regional studies and the Spanish National Study of Adverse Events (ENEAS) determining their impact and preventability.

Materials and methods Case series analysis. A database of 9320 records of patients taking part in three retrospective cohort studies (sharing study protocols and forms) aimed to identify Adverse Events (AE) associated directly with medical care in Spain, was searched to analyse the eight entries related to ADE per patient (error and drug category, route of administration, impact, personal involved, preventability). Descriptive statistics were used.

Results A series of 271 ADEs was identified. 112 (41.5%) were considered medication errors, therefore preventable and 158 (58.5%) were classified as Adverse Drug Reactions (ADRs). Errors involving drug-related clinical monitoring reached 50.0%, prescription errors 46.7%, and administration errors (more difficult to identify in medical records) 3.3%. Improper fluid replacement was responsible for 10.7% of the errors.

Half of the ADEs were related to intravenous administration. 22.9% of events involved antibiotics. The ADR analysis showed 43.8% gastrointestinal AEs, 14% haematological AEs and 12% cardiovascular AEs. 234 medicines-related problems (MRP) had enough information to allow analysis. We categorised 10 “Untreated conditions”, 4 “Drug use without indication”, 5 “Improper drug selection”, 7 “Subtherapeutic dose”, 34 “Overdose”, 158 “ADRs” and 16 “lack of adequate monitoring”.

Conclusions The most frequent problems were digestive ADRs and overdose. A large proportion were preventable errors. The difference in incidence observed with specific studies focusing exclusively on ADEs shows that little information allowing ADE identification is contained in medical records, but this register is of great value allowing the emergence of underreported errors in specific studies like those related to fluid replacement.

No conflict of interest.