Psychometric evaluation of the treatment entry questionnaire to assess extrinsic motivation for inpatient addiction treatment.

Introduction: Valid multi-faceted measurement of motivation for substance use disorder (SUD) treatment is needed to help inform treatment approaches and predict outcomes. This study examined evidence of validity for the Treatment Entry Questionnaire (TEQ-9). Methods: Data represented individuals entering inpatient SUD treatment (n = 1455). We used confirmatory factor analysis (CFA) to assess the three-factor structure of the TEQ-9 [identified (i.e., values/personally chooses treatment), introjected (i.e., internally controlled by guilt/shame) and external motivations (i.e., external pressure/demands)], and examined measurement invariance across gender, age, and ethno-racial identity. Correlation with readiness and confidence assessed convergent validity, while correlations with substance use problem severity and previous substance use treatment assessed meaningful group differences. Results: A three-factor structure was confirmed with all items loading significantly onto their respective factors (ps < 0.001). Each subscale demonstrated high internal consistency (Identified α = 0.90; Introjected α = 0.79; External α = 0.85). Each subscale demonstrated measurement invariance up to the scalar level across all sub-groups. Readiness, confidence, and substance use problem severity correlated as expected across various substances with the identified (rs = 0.098 - 0.262, ps < 0.05), and external (rs = -0.096 - -0.178, ps < 0.05) subscales. Additionally, the mean Identified subscale score was significantly higher among those who previously engaged in SUD treatment (p < 0.001). Findings for the Introjected subscale were more ambiguous. Conclusions: Findings provide evidence for factorial validity, measurement invariance, convergent validity and group differences of the TEQ-9 in a large clinically mixed inpatient SUD treatment population, providing further support of its clinical and research utility.