Integrated Infectious Disease and Substance Use Disorder Care for the Treatment of Injection Drug Use-Associated Infections: A Prospective Cohort Study With Historical Control

Abstract

Background: To address the infectious disease (ID) and substance use disorder (SUD) syndemic, we developed an integrated ID/SUD clinical team rooted in harm reduction at a county hospital in Miami, Florida. The Severe Injection-Related Infection (SIRI) team treats people who inject drugs (PWID) and provides medical care, SUD treatment, and patient navigation during hospitalization and after hospital discharge. We assessed the impact of the SIRI team on ID and SUD treatment and healthcare utilization outcomes.

Methods: We prospectively collected data on patients seen by the SIRI team. A diagnostic code algorithm confirmed by chart review was used to identify a historical control group of patients with SIRI hospitalizations in the year preceding implementation of the SIRI team. The primary outcome was death or readmission within 90 days post-hospital discharge. Secondary outcomes included initiation of medications for opioid use disorder (MOUD) and antibiotic course completion.

Results: There were 129 patients included in the study: 59 in the SIRI team intervention and 70 in the pre-SIRI team control group. SIRI team patients had a 45% risk reduction (aRR, 0.55 [95% confidence interval CI, .32-.95]; 24% vs 44%) of being readmitted in 90 days or dying compared to pre-SIRI historical controls. SIRI team patients were more likely to initiate MOUD in the hospital (93% vs 33%, P < .01), complete antibiotic treatment (90% vs 60%, P < .01), and less likely to have patient-directed discharge (17% vs 37%, P = .02).

Conclusions: An integrated ID/SUD team was associated with improvements in healthcare utilization, MOUD initiation, and antibiotic completion for PWID with infections.

Keywords: buprenorphine; injection drug use; injection-related infection; opioid use disorder; substance use disorder.

Figure 1.

Flow diagram of construction of retrospective control cohort. Diagram demonstrating results of diagnostic code search algorithm to identify severe injection-related infection (SIRI) hospitalizations in the control period (March 2019–February 2020). Hospitalizations were identified that contained a diagnostic code for drug use and for infection. Charts were individually reviewed to determine if the hospitalization was for a SIRI. For the 252 excluded cases, despite the diagnostic codes, no evidence of a valid infection, probable injection drug use, or neither was identified. For individuals with multiple SIRI hospitalizations in the study period, only the first was used. Abbreviations: ICD-10, International Classification of Diseases, Tenth Revision; SIRI, severe injection-related infection.

Figure 2.

Kaplan-Meier curve of readmission-free survival after hospital discharge between severe injection-related infection (SIRI) team and control patients. Kaplan-Meier survival plot with outcome of alive and free from hospital readmission comparing SIRI team patients to historical control group. Numbers show the sum of patients remaining alive and free from readmission after discharge from initial hospital stay at 15-day increments. All remaining patients were censored at 90 days after hospital discharge.