Changes in medication regimen complexity index following medication-related hospital admissions: A retrospective single-centre study

Background: Medication-related hospitalisations present an opportunity for de-prescribing and simplification of medication regimens. The Medication Regimen Complexity Index (MRCI) is a tool for measuring the complexity of medication regimens. Objectives: To evaluate whether MRCI changes following medication-related hospitalisations, and to evaluate the relationship between MRCI, length of stay (LOS) in hospital, and patient characteristics.Methods: A retrospective medical record review of patients admitted to a tertiary referral hospital in Australia for medication-related problems, January 2019 to August 2020. MRCI was calculated using pre-admission medi-cation lists and discharge medication lists.Results: There were 125 patients who met inclusion criteria. The median (IQR) age was 64.0 years (45.0-75.0) and 46.4% were female. Median MRCI decreased by 2.0 following hospitalisation: from median (IQR) 17.0 (7.0-34.5) on admission vs 15.0 (3.0-29.0) on discharge (p < 0.001). Admission MRCI predicted LOS >= 2 days (OR 1.03, 95%CI 1.00-1.05, p = 0.022). Allergic reaction-related hospitalisations were associated with lower admission MRCI. Conclusions: There was a decrease in MRCI following medication-related hospitalisation. Targeted medication reviews for high-risk patients (e.g., those with medication-related hospitalisations) could further reduce the burden of medication complexity following discharge from hospital and possibly prevent readmissions.