BACKGROUND: Patients with substance use disorder (SUD) have high rates of hospitalization, readmission, and prolonged lengths of stay.

OBJECTIVES: To conduct a systematic review and meta-analysis of the impact of addiction consult services in the inpatient setting for patients with SUD.

METHODS: Five databases were systematically searched from their earliest available records through January 2025. Two authors independently screened articles, extracted data, and assessed the quality of each study with the Newcastle-Ottawa Scale for observational studies and the Cochrane risk-of-bias tool for randomized clinical trials. Pooled odds ratios (ORs) with 95% CIs were calculated for dichotomous outcomes, and mean differences were calculated for continuous outcomes.

RESULTS: The search retrieved 20 studies that met inclusion criteria. The intervention for all studies was an addiction medicine consult, but the definition of this consult varied. The meta-analysis did not detect statistically significant differences in hospital length of stay, hospital readmission, or emergency department visits at 1 year among patients who received the consult compared with those who did not; however, many of these outcomes were likely underpowered. However, addiction medicine consults significantly improved the odds of inpatient initiation of medication for SUD (OR, 7.30; 95% CI, 3.30-16.13; <.001) and postdischarge SUD treatment linkage and adherence (OR, 3.31; 95% CI, 2.06-5.32; <.001).

CONCLUSION: Inpatient addiction consult services are associated with increased inpatient initiation of medication for SUD treatment and postdischarge treatment linkage and adherence. No clear association was identified between the consult and readmissions, emergency department utilization, or length of stay.