Adverse drug reactions in hospital in-patients: a pilot study

Abstract

About 6.5% of admissions to hospital are related to an adverse drug reaction (ADR). There are no recent large studies, which explore the burden of ADRs on hospital in-patients. The aim of this pilot study was to assess the feasibility of, and establish the methodology for, conducting a large prospective study to fully assess the impact of ADRs on in-patients and the National Health Service (NHS). Patients admitted to five wards in a university hospital over a 2-week period were assessed for ADRs through a daily ward visit by a pharmacist. Suspected ADRs were analysed for causality, severity and avoidability using appropriate scales. Twenty-four of 125 patients (19.2%, 95% CI 12-26%) were categorized as having suffered one or more ADRs. A total of 27 ADRs were identified. Patients with ADRs spent longer in hospital than those without ADRs. Causality assessment showed that 17 (63%) ADRs were possibly drug-related, whereas 10 (37%) were classified as probably or definitely related to the drug. Almost two-thirds of reactions were potentially avoidable. Intervention was required in all ADRs and reactions indirectly contributed to the death of two patients. Almost one-fifth of patients suffered an ADR as an inpatient. Methodology tested using this pilot will enable the design of a larger study, involving over 3000 patients, which will allow the ADR burden and vulnerable patient groups, to be more accurately characterized. This study will aid the development of interventions to reduce the impact of ADRs in hospital in-patients.