Characterizing the reinforcing value of tobacco using a cigarette purchase task: An item response theory approach

The Cigarette Purchase Task (CPT) affords a high-resolution index of the reinforcing efficacy of nicotine. Although a high number and steep progression of prices have traditionally been used, attention is now placed on developing brief measures of this task. This study sought to assess the psychometric properties of a brief CPT for assessing cigarette demand in treatment-seeking smokers with and without depressive symptoms. The study sample comprised 360 participants (210 with and 150 without depressive symptomatology). We tested the effect of different CPT price densities (14-19) on the variation of CPT indices and provided a thorough assessment of its reliability using 2 different approaches: the classical test theory and item response theory models. Reliability analyses indicated that the 14-item CPT performed the best in terms of reliability across study samples. The CPT's information functions for this shortened version yielded the highest precision at medium levels of the measured construct (for theta values between -0.4 and 0.4). O_max (nondepressed: discrimination parameter a = 14.66; depressed smokers: a = 6.73) and elasticity (nondepressed: a = -3.89; depressed smokers; a = -2.97) best discriminated between patients with different levels of cigarette demand. Results support the utility of item response theory to evaluate the precision of the CPT for different levels of the reinforcing efficacy of nicotine. A 14-item CPT stands as a reliable and efficient method for research and clinical purposes. This task performs particularly well with depressed and nondepressed smokers endorsing moderate levels of the CPT construct. (PsycInfo Database Record (c) 2020 APA, all rights reserved).