Nicotine dependence symptoms among adolescents with psychiatric disorders: using a Rasch model to evaluate symptom expression across time.

Little is known about the longitudinal course of symptoms of nicotine dependence among adolescents following interventions designed to affect smoking behavior, particularly among high-risk samples. We used an item-response modeling strategy to examine how well nicotine dependence symptoms cohere to a latent construct, the stability of the construct over time, and the sensitivity of the nicotine dependence symptoms to changes in smoking patterns among adolescents with comorbid psychopathology. Assessments occurred prior to cessation treatment delivered within a randomized clinical trial and again at 6 and 12 months after treatment. We used a Rasch item-response modeling approach to examine nicotine dependence as measured by a structured Adolescent Nicotine Dependence Interview (ANDI) and by the Modified Fagerström Tolerance Questionnaire (mFTQ). These analyses provided support for a unidimensional latent measurement model that can be used to organize symptoms of nicotine dependence obtained from ANDI and mFTQ measures. The derived measure showed good construct validity with significant relationships to smoking levels and salivary cotinine levels. The typical symptom patterns and the relative severity of nicotine dependence symptoms remained stable over multiple assessments. Changes in smoking levels were related longitudinally to changes in nicotine dependence, and changes in nicotine dependence were related to changes in motivation to quit and readiness to change smoking behavior. Several behavioral symptoms were sensitive to change in smoking rate over time, whereas core symptoms of physiological dependence did not evidence significant changes. Results suggest that DSM-IV and mFTQ measures of nicotine dependence provide complementary information when assessing nicotine dependence levels among adolescents with psychiatric disorders.