Psychometric properties of Severson smokeless tobacco dependence scale among Turkmen male Nass users in Iran

Nass is a form of smokeless tobacco (SLT) commonly used by the Turkmen population in Iran, and its consumption is associated with nicotine dependence. This study aimed to evaluate the psychometric properties of the Persian version of the Severson Smokeless Tobacco Dependence Scale (SSTDS) among Turkmen Nass users in Iran In this cross-sectional study, 327 Turkmen Nass consumers were recruited using convenience sampling. Participants completed the SSTDS, the Fagerström Tolerance Questionnaire for Smokeless Tobacco (FTQ-SLT), and provided demographic information. Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) were used to assess the scale's structure, while reliability was evaluated using standardized Cronbach's alpha and item-total correlations. Criterion validity was assessed by correlating the SSTDS with the FTQ-SLT. EFA suggested a unidimensional model for the SSTDS, which was further supported by CFA, showing a good model fit (CFI = 0.996, TLI = 0.994, WRMR = 0.657, and acceptable RMSEA = 0.071). The factor loadings ranged from 0.54 to 0.87, indicating good convergent validity. The scale demonstrated strong criterion validity, with a significant correlation with the FTQ-SLT (r = 0.65, p < 0.0001). The standardized Cronbach's alpha was 0.855, and the Factor Determinacy Index (FDI) was 0.93, confirming high reliability. The Persian version of the SSTDS is a reliable and valid tool for assessing smokeless tobacco dependence among Turkmen Nass users in Iran. Its validated unidimensional structure makes it a practical and easy-to-use instrument for determining nicotine dependency levels in this specific population for both clinical and research purposes.