Hospitalisations and emergency department visits due to drug–drug interactions: a literature review

PURPOSE: Our objective was to evaluate the incidence of adverse patient outcomes due to drug-drug interactions (D-DIs), the type of drugs involved and the underlying reason. As a proxy for adverse patient outcomes, emergency department (ED) visits, hospital admissions and re-hospitalisations were assessed. METHODS: A literature search in the Medline and Embase database (1990-2006) was performed and references were tracked. An overall cumulative incidence was estimated by dividing the sum of the cases by the sum of the study populations. RESULTS: Twenty-three studies were found assessing the relationship between D-DIs and ED-visits, hospitalisations or re-hospitalisations. The studies with a large study size showed low incidences and vice versa. D-DIs were held responsible for 0.054% of the ED-visits, 0.57% of the hospital admissions and 0.12% of the re-hospitalisations. In the elderly population, D-DIs were held responsible for 4.8% of the admissions. Drugs most often involved were NSAIDs and cardiovascular drugs. The reasons for admissions or ED-visits, which were most often found were GI-tract bleeding, hyper- or hypotension and cardiac rhythm disturbances. CONCLUSION: This review provides information on the overall incidence of D-DIs as a cause of adverse patient outcomes, although there is still uncertainty about the impact of D-DIs on adverse patient outcomes. Our results suggest that a limited number of drugs are involved in the majority of cases and that the number of reasons for admission as a consequence of D-DIs seems to be modest.