28 DRUG-DRUG INTERACTIONS IN OLDER HOSPITALISED PATIENTS: A PROSPECTIVE PREVALENCE STUDY

Abstract

Abstract Background Drug-Drug Interactions (DDIs) are common in older adults and are associated with increased risk of adverse drug events and hospitalisation. Older adults are particularly susceptible to DDIs due to multimorbidity, polypharmacy and age-related changes in pharmacokinetics. A recently published standardised list of 66 potentially significant DDIs specifically relevant to adults aged ≥ 65 years has been validated by an expert consensus group. The aim of the present study was to prospectively assess the prevalence of DDIs in multimorbid older patients with polypharmacy at the point of unscheduled acute hospital admission, using this 66-item DDI list. Methods 77 unselected consecutive patients aged ≥65 years with ≥3 comorbidities and prescribed ≥5 daily regular medications were included. Medication reconciliations were conducted within 48 hours of admission. Medications were confirmed with two or more sources: the patient, their carer, the general practitioner, or the community pharmacist. Drug prescriptions reflecting pre-admission medication lists were manually screened for DDIs according to the 66-item DDI list. Results 47 participants (61.04%) had ≥1 listed DDI. The most commonly identified DDI was concomitant use of ≥3 centrally-acting neuropsychiatric drugs (n=18, 23.28%), which increases the risk of falls and impaired cognition. A highly significant correlation was found between the number of daily medications and the number of DDIs experienced (Spearman’s ρ=0.512, P<0.001). No statistically significant relationship was found between the number of comorbidities and the number of DDIs (Spearman’s ρ=0.194, P=0.107). No significant differences were detected in the number of DDIs, medications or comorbidities between men and women (P=0.818, P=0.428, P=0.281, respectively). Conclusion The majority (61%) of participants had at least one clinically significant DDI. Given the high prevalence of DDIs in this rapidly growing patient population, frequent review and rationalisation of medications using the 66-item DDI list is indicated to minimize DDIs and enhance medication safety.