Short-Term Adverse Outcomes Related to Medication Use in Older Adults Visiting Emergency Department – a Retrospective Observational Study

Background. Drug-related emergency department (ED) visits are often encountered in the ED but remain unidentified, especially among older adults. Although medication use should be screened in the ED, little is known about their effect on short-term adverse ED outcomes. Therefore, we aimed to determine the association between polypharmacy and potentially inappropriate medication (PIM) use and short-term adverse outcomes in older ED patients. Methods. We retrospectively determined prescribed medications of 392 non-urgently transported community-dwelling patients aged ≥ 75 years. We measured polypharmacy and PIM use with dichotomous and ordinal variables. Comorbidities were assessed with Charlson Comorbidity Index (CCI). Primary outcomes were 90-day mortality, hospital admissions and 90-day ED revisits. Statistically, we used adjusted logistic regression analysis. Results. 80% of the patients had polypharmacy (≥ 5 regular medications) and 30% had excessive polypharmacy (≥ 10 regular medications). Polypharmacy did not predict higher risk of any study outcomes but was associated with a lower risk of 90-day mortality [adjusted OR 0.17 (95% CI 0.06–0.45), p < 0.001]. Excessive polypharmacy predicted a higher risk of 90-day ED revisits [adjusted OR 1.35 (95% CI 1.12–4.93), p = 0.024]. An increasing number of regular medications was associated with a higher risk of 90-day ED revisits [OR 1.09 (95% CI 1.03–1.16), p = 0.014] and a lower risk of 90-day mortality [OR 0.83 (95% CI 0.72–0.94, p = 0.005]. PIM use did not increase risks for any study outcomes. Increasing CCI predicted higher 90-day mortality rates [OR 1.70 (95% CI 1.37–2.10), p < 0.001]. Conclusions. Polypharmacy, defined as use of five or more medications is common among older ED patients but does not increase the risk of short-term adverse outcomes. Rising number of regular medications and excessive polypharmacy increases the risk for 90-day ED revisits. Instead of assessing polypharmacy with currently used numerical thresholds, EDs should screen excessive polypharmacy or use novel numerical thresholds to screen high-risk patients.