A novel approach to stratifying patients for medication review in the emergency department using medications and routine blood tests

Abstract Aims The inconsistent impact of medication review on adverse clinical outcomes suggests that stratification based solely on age and number of medications, without considering disease burden, is inadequate. The aim of this study was to investigate the associations between medication use and FI‐OutRef (a frailty index based on abnormal routine blood tests) with 90‐day readmission or mortality and to evaluate the utility of FI‐OutRef in patient stratification for medication review. Methods This single‐centre, observational, register‐based cohort study included acutely admitted medical patients presenting to the emergency department (ED) of Copenhagen University Hospital Hvidovre, Denmark, who received routine blood tests (including 17 standard biomarkers) between November 2013 and March 2017. Patients <18 years old, missing ≥8 standard biomarkers or who died during hospitalization were excluded. Medications obtained within 4 months prior to hospitalization were categorized based on the number of unique prescriptions: 0, 1, 2–4, 5–9 or ≥10. FI‐OutRef was defined as the number of biomarkers outside reference ranges and categorized according to the following cutoffs: ≤4, 5–7 or ≥8. Results Among 27 873 acutely admitted medical patients (52.5% female; median age 59.3 years), increasing FI‐OutRef was significantly associated with increasing risk of readmission (hazard ratios HRs ranging from 1.36 to 2.75 across levels of medication use) and mortality (HRs 2.65 to 8.82), with the highest HRs observed in patients with lower medication use. Conclusion FI‐OutRef strengthens the association between medication use and risk of 90‐day readmission or mortality and could be an important component in patient stratification for medication review to reduce these adverse clinical outcomes.