Adverse Drug Reactions in a Tertiary Care Emergency Medicine Ward - Prevalence, Preventability and Reporting.

Purpose: To identify the prevalence and preventability of adverse drug reactions (ADRs) in an emergency ward setting in a tertiary hospital in Sweden and to what extent the detected ADRs were reported to the Medical Product Agency (MPA).

Methods: In this prospective cross sectional observational study, 706 patients admitted to one of the Emergency Wards, at the Karolinska University Hospital in Solna, Stockholm during September 2008 -September 2009, were included. The electronic patient records were reviewed for patients' demographic parameters, prevalence of possible ADRs and assessment of their preventability. In addition, the extent of formal and required ADR reporting to national registers was studied.

Results: Approximately 40 percent of the patient population had at least one possible ADR (n = 284). In the multivariable regression model, age and number of drugs were significantly associated with risk of presenting with an ADR (p<0.01 and p<0.001, respectively). Sex was not identified as a significant predictor of ADRs (p = 0.27). The most common ADRs were cardiovascular, followed by electrolyte disturbances, and hemorrhage. In 18 percent of the patient population ADRs were the reason for admission or had contributed to admission and 24% of these ADRs were assessed as preventable. The under-reporting of ADRs to the MPA was 99%.

Conclusions: ADRs are common in Emergency Medicine in tertiary care in Sweden, but under-reporting of ADRs is substantial. The most frequent ADRs are caused by cardiovascular drugs, and significantly associated with age and number of drugs. However, only a minority of the detected serious ADRs contributing to admission could have been avoided by increased risk awareness.