Association of hospital-based substance use supports on emergency department revisits: a retrospective cohort study in Sudbury, Canada from 2018 to 2022

Abstract

Background: This study compares emergency department (ED) revisits for patients receiving hospital-based substance-use support compared to those who did not receive specialized addiction services at Health Sciences North in Sudbury, Ontario, Canada.

Methods: The study is a retrospective observational study using administrative data from all patients presenting with substance use disorder (SUD) at Health Sciences North from January 1, 2018, and August 31, 2022 with ICD-10 codes from the Discharge Abstract Database (DAD) and the National Ambulatory Care Database (NACRS). There were two interventions under study: addiction medicine consult services (AMCS group), and specialized addiction medicine unit (AMU group). The AMCS is a consult service offered for patients in the ED and those who are admitted to the hospital. The AMU is a specialized inpatient medical unit designed to offer addiction support to stabilize patients that operates under a harm-reduction philosophy. The primary outcome was all cause ED revisit within 30 days of the index ED or hospital visit. The secondary outcome was all observed ED revisits in the study period. Kaplan-Meier curves were used to measure the proportion of 30-day revisits by exposure group. Odds ratios and Hazard Ratios were calculated using logistic regression models with random effects and Cox-proportional hazard model respectively.

Results: A total of 5,367 patients with 10,871 ED index visits, and 2,127 revisits between 2018 and 2022 are included in the study. 45% (2,340/5,367) of patient were not admitted to hospital. 30-day revisits were less likely among the intervention group: Addiction Medicine Consult Services (AMCS) in the ED significantly reduced the odds of revisits (OR 0.53, 95% CI 0.39-0.71, p < 0.01) and first revisits (OR 0.42, 95% CI 0.33-0.53, p < 0.01). The AMU group was associated with lower revisits odds (OR 0.80, 95% CI 0.66-0.98, p = 0.03). For every additional year of age, the odds of revisits slightly decreased (OR 0.99, 95% CI 0.98-1.00, p = 0.01) and males were found to have an increased risk compared to females (OR 1.50, 95% CI 1.35-1.67, p < 0.01).

Interpretation: We observe statistically significant differences in ED revisits for patients receiving hospital-based substance-use support at Health Sciences North. Hospital-based substance-use supports could be applied to other hospitals to reduce 30-day revisits.

Keywords: Addiction consult teams; Addiction medicine; Administrative data; Cohort study; Emergency department revisits; Harm-reduction; Observational data; Substance use disorders.

Fig. 1

Study diagram for 30-day re-admission and first readmission

Fig. 2

Clinical Classifications Software Refined (CCSR) Comorbidities per patient at Hospital Grouped by Exposure

Fig. 3

Forest plot of odds ratios for 30-day readmission

Fig. 4

Forest plot for Odds Ratios of first readmission

Fig. 5

Cumulative incidence of 30-day readmission by intervention

Fig. 6

Cumulative incidence of first readmission by intervention