Adverse drug reaction-related hospitalisation in older patients - A prospective analysis in two hospitals

Introduction: Adverse drug reactions (ADRs) are a major cause of hospital admissions in older patients. Despite the magnitude of this problem, there is limited prospective data on ADRs as a cause of hospitalisation in elderly medical patients.

Aims: To ascertain the proportion of ADR-related hospital admissions in older patients admitted in Tasmanian hospitals; to identify the commonly implicated drugs; to describe the clinical manifestations and outcomes of these ADRs; and for each ADR, to determine the causality, preventability and severity.

Methods: We conducted a prospective cross-sectional study at the Royal Hobart (March 2014 - March 2015) and Launceston General Hospitals (September - December 2015) in Tasmania, Australia. A convenience sample of patients aged 65 years and older undergoing unplanned, overnight medical admissions was screened. ADR-related admissions were determined through expert consensus from detailed review of medical records and patient interviews. The causality between drug use and ADRrelated hospital admission was evaluated using the Naranjo algorithm. The preventability and severity of each ADR admission were assessed using Schumock and Thornton criteria and Hartwig’s criteria, respectively.

Results: The proportion of ADR-related hospital admissions was 19% of 1008 admissions. Most (89%) ADR-related admissions were considered preventable. Cardiovascular complaints (26%) represented the most common ADRs, followed by renal (20%) and nervous system disorders (15%). The drugs most frequently responsible were diuretics (20%), agents acting on the renin angiotensin system (20%), beta-blockers (8%) and psychoanaleptics (7%). Application of the Naranjo algorithm found 6% definite, 70% probable and 24% possible ADRs contributed to the hospital admissions. ADR severity was rated moderate in 98% and severe in 2% of admissions. For most admissions (98%) the ADR resolved and the patient recovered.

Discussion: Hospitalisation due to an ADR is a common occurrence in older Australians. Improved medication management services to prevent these admissions are urgently required.