Adverse drug reactions as a cause of admission to an acute medical assessment unit: a pilot study

Background: In this pilot study, we have investigated the frequency of adve rse drug reaction (ADR)-related admissions to an acute medical assessment u nit. Although ADRs are thought to be responsible for 5% of hospital admissi ons, there have been no recent studies in the U.K. Objective: To pilot such a study for estimating the incidence of ADR-relate d admissions to an acute medical assessment unit. Method: Data were collected for 200 patients including details of concurren t illness, drug usage and reasons for admission. ADRs were assessed for cau sality using two previously published classification systems. Results: ADRs were responsible for admission in 15 (7.5%) patients, were pr esent in an additional three (1.5%) patients and may have contributed to th e deaths of two (1%) patients. Of the 15 ADRs suspected of causing an admis sion, three were considered to be 'possible' or 'unlikely', with the remain ing 12 considered to be 'probable' or 'certain'. The proportion of patients identified in this study with ADR-related admissions is either similar to or larger than that found in comparable studies carried out in other hospit als. Nearly all ADRs were Type A reactions in that they were predictable an d therefore potentially preventable. Conclusion: This study suggests that the proportion of ADR-related admissio ns has not decreased in the last decade and, given the increasing numbers o f acute medical admissions, the absolute numbers may have actually increase d. Furthermore, the nature of drugs causing admissions has not changed subs tantially over the last 20 years. Strategies to reduce the burden of ADR-re lated admissions are urgently needed.