Using INTERCheck ® to Evaluate the Incidence of Adverse Events and Drug–Drug Interactions in Out- and Inpatients Exposed to Polypharmacy

Background Polypharmacy exposes patients with comorbidities (particularly elderly patients) to an increased risk of drug-specific adverse events and drug–drug interactions. These adverse events could be avoided with the use of a computerized prescription support system in the primary care setting. The INTERCheck ® software is a prescription support system developed with the aim of balancing the risks and benefits of polytherapy and examining drug–drug interactions. Objectives This observational study used the INTERCheck ® software to evaluate the incidence of adverse events and of drug–drug interactions in outpatients and inpatients receiving multiple medications. Methods Patients were randomly enrolled from the outpatient department ( n = 98) and internal medicine ward ( n = 46) of S. Andrea Hospital of Rome. Polypharmacological treatment was analyzed using INTERCheck ® software, and the prevalence of risk indicators and adverse events was compared between the two groups. Results Polypharmacy (use of five or more drugs) applied to all except three cases among outpatients and one case among inpatients. A significant positive correlation was found between the number of medications and the INTERCheck ® score ( ρ = 0.67; p < 0.000001), and a significant negative correlation was found between the drug-related anticholinergic burden and cognitive impairment ( r = − 0.30 p = 0.01). Based on the INTERCheck ® analysis, inpatients had a higher score for class D (contraindicated drug combination should be avoided) than did outpatients ( p = 0.01). The potential class D drug–drug interactions were associated with adverse events that caused hospitalization ( χ 2 = 7.428, p = 0.01). Conclusions INTERCheck ® analysis indicated that inpatients had a high risk of drug–drug interactions and a high percentage of related adverse drug events. Further prospective studies are necessary to evaluate whether the INTERCheck ® software may help reduce polypharmacy-related adverse events when used in a primary care setting and thus potentially avoid related hospitalization and severe complications such as physical and cognitive decline.