Psychometric Evaluation of the Opiate Dosage Adequacy Scale: Reliability and Convergent Validity Among Non-European Spanish-speaking Buprenorphine Patients

Thairys Flores Ocasio¹Nicole Melendez Rivera¹Jorge Duconge¹Raman Venkataramanan²Francisco González-Saiz³Darlene Ivelisse Santiago^1*

• ¹Universidad de Puerto Rico Recinto de Ciencias Medicas, San Juan, Puerto Rico
• ²University of Pittsburgh School of Pharmacy, Pittsburgh, United States
• ³Universidad de Cadiz Facultad de Medicina, Cádiz, Spain

Objective: The opiate dose adequacy scale (ODAS) is a semi-structured clinical scale that assesses the adequacy of buprenorphine doses by evaluating continued heroin use, cravings, narcotic blockade, objective and subjective withdrawal symptoms, and overmedication. While it has been validated in European populations, its use in other Spanish-speaking populations beyond Europe remains unexplored. This study addresses this gap by evaluating the psychometric properties and clinical utility of the ODAS among Hispanic patients with opioid use disorder (OUD) in Puerto Rico—an underserved and distinct group. Methods: A cross-sectional study was conducted with 111 buprenorphine-maintained patients. The ODAS was administered alongside clinical stabilization measures, including the Severity of Dependence Scale (SDS), urine toxicology results, buprenorphine dose, and plasma drug concentrations. Internal consistency was assessed using Cronbach’s alpha. Receiver operating characteristic (ROC) analysis was performed to determine the optimal ODAS cut-off score for dose adequacy classification using Youden’s Index. Results: A total of 54.9% of participants were classified as adequately dosed using ODAS qualitative criteria. The ODAS score showed significant inverse correlations with SDS scores, illicit opioid use, and buprenorphine dose. Plasma levels were positively associated with dose adequacy. Internal consistency was moderate (Cronbach’s α = 0.615). ROC analysis demonstrated excellent discriminative ability (AUC = 0.996), and an ODAS score of ≥29 was identified as the optimal threshold for classifying adequate dosing. Conclusion: These findings support the validity of the ODAS as a psychometric tool for assessing buprenorphine dose adequacy in Spanish-speaking populations beyond Europe. By extending psychometric validation this work addresses a critical gap in culturally and linguistically appropriate treatment tools. The ODAS may serve as a valuable clinical instrument for improving individualized treatment strategies among Spanish-speaking communities across the United States and Latin America, addressing a critical gap in psychometric validation and promoting equity in clinical care for Spanish-speaking communities.