Background and Importance Drug-related problems (DRPs) are a common reason for visiting the emergency departments (ED). However, the information available on risk factors associated with new ED visits based on the patient‘s pharmacotherapy is limited.

Objective To develop a predictive model of the risk of revisiting the ED at 30 days based on patients’ treatment at discharge.

Methods Retrospective cohort study involving adult patients who attended the ED in Catalonia (Period: 2019) with a triage level of 1–3. A 30-day return visit prediction model was created in a referral cohort (60%) using a logistic regression model, being validated in a validation sample (40%). Variables included in the multivariate analysis were assigned a score proportional to the regression coefficient. The sociodemographic variables considered in this study were age, sex and income level, multimorbidity burden based on the Adjusted Morbidity Groups (GMA). Forty-four groups of drugs associated with DRPs were evaluated.

Results 851,649 patients were included [201,445 (23.6%) with >9 drugs prescribed at discharge], of whom 134,560 (15.8%) visited the ED after 30 days. The four variables evaluated (sex, age, GMA, and income level) and 34 ATC groups were associated with the risk of repeat ED consultation and were combined into a final score (DRP-Score). The drugs with the highest risk score were osmotic laxatives (RR:1.421(95% CI:1.264–1.596)), b-lactam antibiotics (1.333(1.123–1.583)), digoxin (1.282 (1.256–1.309)), heparins (1.150 (1.112–1.190) and lithium (1,146 (1.000–1.315)) The model achieved an area under the receiver operating curve (AUC-ROC) values of 0.648 (95% CI: 0.646–0.650) in the reference cohort and 0.647 (0.644–0.649) in the validation group. Three risk categories were generated, with the following estimated risks of revisiting the ED at 30 days: low risk: 10.2%, intermediate risk: 18.3%, and high risk: 28.4%. The score was validated in a sample of 1437 patients who visited the ED for DRPs, maintaining its predictive capacity.

Conclusion and Relevance The DRP-score identifies patients at high risk of returning to the ED within 30 days based on pharmacotherapy, being a useful tool for prioritizing interventions from these units.