Factor Analysis and Psychometric Properties of the Minnesota Nicotine Withdrawal Scale and the Minnesota Nicotine Withdrawal Scale-Revised: Italian Version

Psychometric Validity of the Minnesota Tobacco Withdrawal Scale in Smokers Attempting to Quit: Longitudinal Invariance across Smokers and Abstainers

Tobacco withdrawal symptoms vary during smoking cessation increasing relapse risk; therefore, a longitudinal invariant measure seems necessary to validly assess withdrawal changes. This study aimed to examine the psychometric properties of the 7-item Minnesota Tobacco Withdrawal Scale (MTWS) during cessation, and to analyze longitudinal invariance across smokers and abstainers. We conducted a longitudinal study with 309 Spanish smokers (56.2 ± 9.9 years; 52.4% women). We assessed withdrawal at three occasions: pre-treatment (T1), week-12 (T2), and week-24 (T3). Reliability, validity, and invariance analyses were performed. MTWS reliability remained adequate over time (ωT1 = 0.78; ωT2 = 0.68; ωT3 = 0.80) in both smokers and abstainers, with satisfactory temporal stability (ICC = 0.73). MTWS correlations with anxiety, depression, and nicotine dependence (rs > 0.3) supported convergent and concurrent validity. MTWS showed no correlation with craving at T2 (rs < 0.24), suggesting discriminant validity. Unifactorial structure proved partial scalar invariance across time (χ2 = 246.009; CFI = 0.91; IFI = 0.91; SRMR = 0.09), yet longitudinal invariance between abstainers and smokers was not supported. Across groups, partial scalar invariance was only achieved at T2. Noninvariance at T3 was mainly due to item irritability (dMACS = 0.93). The MTWS is reliable and valid measure to assess withdrawal changes during cessation. Long-term MTWS comparisons between smokers and abstainers should be taken with caution since different withdrawal patterns may exist.

Validation of the Glover-Nilsson Smoking Behavioral Questionnaire (GN-SBQ) to Evaluate Nicotine Dependence in Spanish Clinical Settings

An assessment of the different aspects of tobacco addiction is central to adapting interventions to the profiles and needs of smokers. The Glover−Nilsson Smoking Behavioral Questionnaire (GN-SBQ) is one of the few and most used scales to evaluate the behavioral aspects of tobacco addiction. However, few studies involve the validation of the GN-SBQ in clinical settings. Thus, this study aimed to analyze the psychometric properties of the GN-SBQ in a sample of Spanish smokers. A total of 341 smokers attending clinical services in Spain participated in this cross-sectional study. Measures included the psychological factors related to tobacco addiction, assessed with the GN-SBQ, the physical factors of nicotine addiction, withdrawal symptoms, smoking-related variables, and alcohol use. Data analysis included descriptive statistics, internal consistency coefficients, confirmatory factor analyses, Spearman correlations, and the Kruskal−Wallis test. The GN-SBQ showed adequate reliability (α = 0.76 and ω = 0.76) and a unidimensional structure. GN-SBQ scores also provided evidence of convergent and concurrent validity. GN-SBQ scores significantly correlated with the physical symptoms of addiction, age, number of cigarettes, and withdrawal symptoms. The results of discriminant validity were also adequate, as no correlation was observed between GN-SBQ scores and CO levels or alcohol use. Significant differences were found between all levels of psychological addiction based on the GN-SBQ scores regarding physical nicotine addiction, withdrawal symptoms, and age. Thus, this questionnaire is a reliable and valid instrument to assess the psychological aspects of tobacco addiction in smokers in clinical settings. The short length of the GN-SBQ proves advantageous for its use in time-limited assessments, which are common in public health services.

Construct validity of the Smoker Complaint Scale: A clinimetric analysis using Item Response Theory (IRT) models

A number of rating scales evaluating symptoms of nicotine withdrawal have been developed over the years but insufficient attention has been devoted to the assessment of their clinimetric properties. Clinimetrics, the science of clinical measurements, is an innovative approach, particularly useful for assessing the validity of rating scales. This is the first study using clinimetric principles to test the construct validity of the Smoker Complaint Scale (SCS), a self-rating scale specifically developed to assess acute symptoms of nicotine withdrawal. Construct validity was evaluated via Item Response Theory (IRT) models (i.e., combining Rasch and Mokken analyses). A total of 366 subjects (mean age = 34.0, SD = 11.3 years) participated in the study. IRT analyses showed that SCS was a multidimensional measure of symptoms of nicotine withdrawal, including unidimensional subscales, particularly a four-item subscale (the SCS₄), which was found to entail the clinimetric property of construct validity. IRT analyses also revealed that affective symptoms of nicotine withdrawal preceded cognitive ones. The SCS should be considered as an item bank, including a particularly valid subscale, the SCS₄ that can be used as a screening or outcome measure to evaluate the severity of cognitive and affective symptoms of nicotine withdrawal. SCS₄ is a sensitive clinimetric index which differentiates "ceiling symptoms" of nicotine withdrawal (e.g., "feeling slowed down") from "floor symptoms" of nicotine withdrawal (e.g., "feeling lightheaded") that emerge in the severe form of nicotine withdrawal.