Background: Adverse drug events (ADE’s) are a major problem in healthcare and can lead to increased hospital admissions, length of stay, and healthcare costs. With appropriate intervention, ADE’s are largely preventable. The purpose of this study is to ascertain risk factors for ADE’s and hospital readmissions in inpatients on a general medicine service at a public teaching hospital. This study is the pilot for a quality improvement initiative to decrease ADE’s and 30-day readmissions by developing a medication counseling intervention targeted to high-risk patients.

Methods: A retrospective chart review was performed on patients discharged between January 4, 2016 and January 18, 2016. Patients were excluded if they left against medical advice, eloped, expired, or were admitted to or discharged from a service other than medicine. We identified possible risk factors for ADE’s and hospital readmissions (Table 1). ADE’s were defined as adverse drug reactions (such as iatrogenic hypoglycemia, bleeding, or electrolyte abnormalities or the development of a new drug allergy) and medication administration errors. The primary outcome, incidence of ADE’s during hospital admission, was identified via review of the medical chart and hospital incident reports. The secondary outcome was 30-day readmission to our institution.

Results: 197 patients were identified for chart review, and 168 patients were included in the final analysis. 11% of patients (18/168) had one or more ADE’s during inpatient hospitalization and 15% (25/168) were readmitted within 30 days. Risk factors prevalent in fewer than 10% of the study population were not analyzed due to insufficient power. The final analysis included 10 risk factors.  Age ≥ 65 years was a statistically significant risk factor for ADE’s during inpatient hospitalization (odds ratio [OR]=3.4, 95% CI 1.15-10.0, p=0.02), even after adjusting for confounding risk factors. Diabetes mellitus type 2 (DM2), use of greater than 5 medications prior to admission, and discharge with greater than 5 medications were associated with ADE’s during hospitalization in an unadjusted analysis, but not after adjusting for age ≥ 65 years. DM2 (OR=2.6, 95% CI 1.02-7.80, p=0.046) and end-stage renal disease (ESRD) (OR=3.7, 95% CI 1.25-11.0, p=0.02) were associated with higher risk of 30-day hospital readmission after adjusting for age ≥ 65 years (Table 1).

Conclusions: The most significant risk factor for ADE’s within the population studied was age ≥ 65 years. Furthermore, there is a significant risk for 30-day readmissions in patients with DM2 and ESRD. The results of this study have identified high-risk patients within our institution that would most likely benefit from initiatives to reduce adverse medication events, and ultimately reduce readmissions.