Item analysis of the Leeds Dependence Questionnaire in community treatment centers

The present study extends the item-level psychometric information of the Leeds Dependence Questionnaire (LDQ; Raistrick et al., 1994) that has been purported to measure psychological dependence and the International Statistical Classification of Diseases and Related Health Problems-10th edition substance dependence criteria. Prior research on the LDQ has not established item-level properties or the degree of differential item functioning (DIF) by gender and substance type. Principal component and Mokken scale analyses were used to assess unidimensionality and monotonicity of the responses to the scale items, respectively. Graphical and statistical methods examined the model-data fit of the graded response model and two-parameter logistic model of LDQ responses (n = 1,681) obtained from 2 community treatment centers. DIF analysis was performed on gender (men = 1,313, women = 353) and substance (alcohol = 821, opiates = 528) groups. The 2PL achieved the best model-data fit. Three items provided little information about standing on the underlying construct, indicating that they are likely not good indicators of the "pure" psychological construct the LDQ aims to measure. Overall, the LDQ offers the greatest precision in quantifying psychological dependence in a clinical sample along the lower to mid ranges of this construct. Uniform DIF was present in Item 7 of the dichotomized responses by substance (alcohol vs. opiates). DIF by gender was not found in any of the LDQ items. Recommendations include revising the scaling and discussing the need to obtain LDQ data from different levels of care and primary identified substance. (PsycINFO Database Record