Clinical Characteristics and Treatment Outcomes Among Patients with Fentanyl-Positive Urine Drug Screening in Inpatient Detoxification and Rehabilitation.

Background: Fentanyl is a major driver of overdose mortality in the United States, yet less is known about patients with fentanyl-positive urine drug screening (UDS) entering inpatient addiction treatment. Methods: This retrospective cohort study included patients admitted to an inpatient detoxification and rehabilitation unit at an academic behavioral health center from January 1 to March 31, 2024. Patients were classified according to fentanyl-positive or fentanyl-negative admission UDS; confirmatory testing was not performed. Sociodemographic, clinical, and treatment variables and 1-year readmission were compared using chi-square and t-tests. Kaplan-Meier analysis assessed time to readmission, and multivariable logistic regression identified factors associated with fentanyl-positive UDS. Results: Among 196 patients, 75 (38.3%) had fentanyl-positive UDS. These patients had higher rates of incarceration and polysubstance use. In multivariable analyses, primary opioid use (OR 12.85, 95% CI 3.47-47.65), stimulant use (OR 3.35, 95% CI 1.03-10.91), and incarceration history (OR 4.14, 95% CI 1.43-11.94) were independently associated with fentanyl-positive UDS. Detoxification completion, rehabilitation completion, length of stay, and 1-year readmission (33.7%) did not differ between groups. Conclusions: Fentanyl-positive UDS was common and associated with greater polysubstance use and incarceration history, but not poorer short-term outcomes. Screening-based classification without confirmatory testing and uncertainty regarding the clinical primacy of fentanyl limit conclusions regarding fentanyl-specific effects.