The impact of co-occurring opioid and stimulant use disorders on unplanned readmissions among patients hospitalized with bacterial infections

Opioid and stimulant use disorders (OUD and StUD) are major drivers of injection drug use (IDU)-related bacterial infections requiring hospitalization and may increase readmission risk. However, the independent and combined effects of these factors on short-term readmission risk remain unclear. We examined the association between OUD and/or StUD and unplanned 7-day and 30-day all-cause readmissions among patients hospitalized with IDU-related bacterial infections. We conducted a retrospective cohort study utilizing the 2022 Healthcare Cost and Utilization Project Nationwide Readmission Database (NRD), applying survey weights to generate national estimates. The study included adults hospitalized with a primary diagnosis of skin and soft tissue infections, osteomyelitis, infective endocarditis, or central nervous system abscess. Exposure groups were neither disorder, OUD only, StUD only, and co-occurring OUD and StUD, identified using ICD-10-CM codes. Primary outcomes were unplanned all-cause readmission within 7 days and 30 days of discharge. Among 392,984 weighted index admissions, the mean age was 58.8 years, 57.1% were male, and 46.9% had Medicare coverage. Overall, 4.5% involved OUD only, 3.9% StUD only, and 2.4% co-occurring disorders. Unplanned readmission rates were 4.3% (7-day) and 12.48% (30-day). After adjustment, OUD and/or StUD were associated with higher odds of 7-day and 30-day readmission compared with neither disorder. Although statistically insignificant, patients with co-occurring disorders had higher odds of readmission than those with OUD only. OUD and/or StUD were associated with an increased risk of short-term unplanned readmission after IDU-related bacterial infections. These findings may highlight the potential value of integrating addiction treatment into inpatient infection care.