Polysomnographic arousal index and periodic limb movement index in patients undergoing coronary artery bypass grafting: an exploratory case-comparison study.

The Cigarette Purchase Task (CPT) is a time- and cost-efficient behavioral-economic approach for simulating product demand without administering cigarettes to participants (). The task assesses cigarette demand across a range of hypothetical monetary prices. As a safe and ethical alternative to laboratory drug self-administration tests, the CPT can be an especially useful tool for assessing cigarette demand in highly vulnerable populations, including, for example, pregnant women () or individuals seeking smoking-cessation treatment (). CPT demand typically consists of five indices (): Demand Intensity—the number of cigarettes participants estimate they would smoke if cigarettes were free or minimal cost, also represented as Q; O—maximum expenditure; P—the price associated with O; Breakpoint—the price at which participants estimate they would no longer consume cigarettes; and Elasticity, or α—overall sensitivity of estimated demand to changes in hypothetical price (). Higher product demand, or abuse liability, is indicated by greater estimated consumption and insensitivity to price changes. The demand indices of the CPT are significantly related to measures of tobacco use and nicotine dependence (for reviews, see ; ). The CPT is also highly sensitive to individual differences in cigarette demand (see ), including, for example, serious mental illness (), opioid use disorder (OUD) (), and antepartum quit attempts in pregnant women (; ). Across these studies, individuals with serious mental illness, individuals with OUD, and individuals with fewer antepartum quit attempts exhibited significantly higher CPT demand compared to their respective counterparts. The CPT demand indices have also demonstrated high test-retest reliability (; ; ). These are features of considerable clinical and scientific importance, leading the Consortium on Methods Evaluating Tobacco to recommend the inclusion of the CPT in research that informs US Food and Drug Administration (FDA) tobacco regulation (). The CPT is also included in the PhenX Tobacco Regulatory Research Toolkit, a catalogue of standard measures for biomedical research (). Considering the broad recognition and increasing use of this task, relatively few studies have examined the correspondence between participant estimated hypothetical cigarette consumption on the CPT and actual consumption patterns. Studies investigating this correspondence have reported that demand for cigarettes on the CPT significantly predicts consumption under real purchasing conditions, although participants may be less sensitive to price increases in the hypothetical task (; ). The Demand Intensity index is a CPT parameter that is particularly sensitive to individual markers of smoking risk (; ) and, thus, a helpful metric for informing interventions and tobacco regulatory policies. Although relatively rare, studies that provide participants with free cigarettes present an excellent opportunity to examine associations between the CPT Demand Intensity index and actual cigarette consumption when price is unconstrained. To our knowledge, only three studies have examined this association (; ; ). All three studies demonstrated that CPT Demand Intensity is significantly correlated with actual consumption of free cigarettes, supporting the construct validity of the index. In two of these studies, the differences between Demand Intensity and actual consumption were calculated, and Demand Intensity overestimated consumption by averages of 4.40 (SEM ± 0.19) () and 5.1 (SD ± 5.3) cigarettes per day (CPD) (). Importantly, demonstrated that CPT Demand Intensity and actual cigarette consumption were comparably sensitive to differences in well-established smoking risk factors, including sex, OUD, chronological age, and educational attainment. That is, overestimation did not appear to undermine the practical utility or construct validity of the CPT.