Introduction
This study represents the first clinical descriptive study on opioid use disorder (OUD) in Brazil. 

Methods
This comparative cross-sectional study involved 314 adult patients at the Addiction Outpatient Clinic of Instituto Perdizes, São Paulo, from April 2023 to August 2024. Data were collected through interviews, using the validated Brazilian Portuguese version of the Addiction Severity Index (ASI-6) and the Structured Clinical Interview for DSM-5 (SCID). Statistical analysis included descriptive statistics, chi-square tests for categorical variables, and the Kruskal-Wallis test for continuous variables. 

Results
Patients were evaluated and divided in two groups: OUD group (OUDG) with 45 (14.3%) and non-opioid use disorder group (NOUDG) with 269 (85,87%). In the OUDG, 26.7% were healthcare professionals (p < 0.001; 95%CI 3.34 - 7.92), and there was a high incidence of chronic pain (55.6%) (p < 0.001; 95%CI 2.60 - 4.13). Healthcare utilization was notably higher among OUD patients, with 73.3% attending healthcare services in the past six months (p < 0.001; 95%CI 1.14 - 4.97).

Discussion
Emerging data reveal a growing trend in opioid use in low- and middle-income countries, with Brazil witnessing a notable rise in opioid prescriptions.

Conclusion
Developing effective preventive strategies for OUD is crucial to mitigating its significant public health risks. Chronic pain conditions and healthcare professionals may represent vulnerable groups with an elevated risk of developing OUD.