Factor analysis of treatment outcomes from a UK specialist addiction service: relationship between the Leeds Dependence Questionnaire, Social Satisfaction Questionnaire and 10-item Clinical Outcomes in Routine Evaluation

Introduction and aims: To examine the relationship between three outcome measures used by a specialist addiction service (UK): the Leeds Dependence Questionnaire (LDQ), the Social Satisfaction Questionnaire (SSQ) and the 10-item Clinical Outcomes in Routine Evaluation (CORE-10).

Design and method: A clinical sample of 715 service user records was extracted from a specialist addiction service (2011) database. The LDQ (dependence), SSQ (social satisfaction) and CORE-10 (psychological distress) were routinely administered at the start of treatment and again between 3 and 12 months post-treatment. A mixed pre/post-treatment dataset of 526 service users was subjected to exploratory factor analysis. Parallel Analysis and the Hull method were used to suggest the most parsimonious factor solution.

Results: Exploratory factor analysis with three factors accounted for 66.2% of the total variance but Parallel Analysis supported two factors as sufficient to account for observed correlations among items. In the two-factor solution, LDQ items and nine of the 10 CORE-10 items loaded on the first factor >0.41, and the SSQ items on factor 2 with loadings >0.63. A two dimensional summary appears sufficient and clinically meaningful.

Discussion and conclusions: Among specialist addiction service users, social satisfaction appears to be a unique construct of addiction and is not the same as variation due to psychological distress or dependence. Our interpretation of the findings is that dependence is best thought of as a specific psychological condition subsumed under the construct psychological distress.