Psychometric Properties of the Iranian Brief Version of the Transtheoretical Model Instrument in Terms of Hookah Tobacco Smoking Cessation

Transtheoretical model (TTM) has been recognized as a common theoretical model in researches in terms of addictive behaviors. The aim of this study was to examine the psychometric properties of the Persian brief version of the TTM for hookah tobacco smoking cessation in a sample of Iranian rural adults who were in the preparation stage for hookah cessation. This was a validation study on Iranian rural adult hookah smokers by the TTM instrument. First, to translate the questionnaire items from English to Persian, backward-forward procedure was used. Face and content validity of the instrument items were assessed. Confirmatory factor analysis (CFA) was performed to determine the construct validity of the instrument. For this aim, 300 participants completed the instrument. Cronbach's alpha coefficient and intraclass correlation coefficient (ICC) were calculated to examine the internal consistency and reliability of the subscales of the instrument. The content validity index (CVI) and content validity ratio (CVR) of the items were ≥ 0.80 and ≥ 0.60, respectively. Based on CFA, the data fitted the TTM model. root mean square error of approximation (RMSEA), the goodness of fit index (GFI), adjusted GFI, and comparative fit index (CFI) were 0.037, 0.960, 0.910, and 0.950, respectively. At this stage, 6 items were deleted. The ICC and Cronbach's alpha of the subscales ranged between 0.60-0.74 and 0.71-0.86, respectively. The final instrument with 29 items was confirmed. The findings suggest that translating Persian brief version of the TTM instrument was a reliable and valid tool to identify the determinants of hookah smoking cessation among Iranian rural adults.