Costs associated with adverse drug reactions in an older population admitted to hospital: A prospective cohort study

Abstract

Purpose This study examines healthcare costs associated with adverse drug reactions (ADR) in an older population admitted acutely to an Irish tertiary hospital. Methods This is a prospective cohort study involving older persons admitted to hospital with and without an ADR. Data was collected at baseline during hospitalisation and after hospital discharge. Participants provided information on healthcare resource use three months before and after discharge. For each healthcare resource, unit costs were derived and applied. Average, accumulated costs of hospitalisation and related health and social care were calculated. The average costs associated with ADR and non-ADR hospitalisation and post-discharge care were compared using difference-in-difference analysis and presented with 95% confidence intervals (CI). Costs by preventability and severity of ADR are also presented. Results A total of n=230 participants were included (n=93 associated with ADR and n=137 without ADR). The average cost associated with an ADR was estimated at €2047 (95% CI: -€889 to €4983). The mean incremental cost of definite preventable ADRs was estimated at €1648 (95% CI: -€4310 to €7605), possible preventable ADRs €2259 (95 CI: -€1194 to €5712) and unavoidable ADRs €1757 (95% CI: -€3377 to €6890). The mean incremental cost associated with moderate severe ADRs was estimated at €1922 (95% CI: -€1088 to €4932) and €3580 (95% CI: -€4898 to €12058) for severe ADRs. Conclusion ADRs leading to hospital admission are associated with modest incremental healthcare costs during and three months after admission. Severe and possibly preventable ADRs were associated with higher costs.