Development of an instrument based on the theory of planned behavior variables to measure factors influencing Iranian adults’ intention to quit waterpipe tobacco smoking

摘要

Background: Theory of planned behavior (TPB) is one of the most widely used theoretical frameworks to explain addictive behaviors, such as tobacco smoking. The aim of this study is to develop and validate an instrument based on TPB variables to measure factors influencing Iranian rural adults’ intention to quit waterpipe tobacco smoking. Methods: This study was performed on a sample of rural adult waterpipe consumers living in two villages in Shiraz, Southern Iran. In the beginning, the initial items of instrument were extracted from the literature review and interviews with 20 waterpipe consumers. After that, face validity and qualitative content validity of the items were appraised. To measure quantitative content validity index (CVI) and the content validity ratio (CVR), a panel of experts reviewed the items. In addition, the exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were applied to characterize the construct validity of the instrument. Finally, Cronbach’s alpha coefficient and intraclass correlation coefficient (ICC) were computed. Results: CVI and CVR of items were within the ranges of 0.89–0.95 and 0.85–0.96, respectively. EFA indicated the Kaiser-Meyer-Olkin (=0.71) and Bartlett’s test of sphericity was significant (=912.36, df=105, p 0.0001). Principal component analysis revealed that 15 items could be grouped into four subscales that accounted for 64.97% of the variance. Based on CFA, two items were deleted. CFA results showed that the remained data were fit to the model. The Cronbach’s alpha and ICC of subscales were, respectively, in the ranges of 0.72–0.87 and 0.64–0.82. Finally, a 13-item instrument with four subscales was confirmed. Conclusions: The findings reveal that the developed TPB instrument is a reliable and valid scale to identify the determinants of the intention to quit waterpipe smoking among Iranian rural adults.