Background:
Fagerstrom Test for Nicotine Dependence (FTND) is widely used screening instrument for physical nicotine dependence. Psychometric properties of FTND have been validated among cigarette smokers, but the reliability and validity of its variant for smokeless tobacco users and bidi smokers is not well documented. The present study aims to evaluate reliability, construct validity, and structure model of FTND among bidi smokers and smokeless tobacco users.

Methods:
A cross sectional survey was conducted among 1350 patients visiting primary care facilities in two states of India in 2016. FTND contains six items that evaluate the quantity of tobacco consumption and dependence. Cronbach´s coefficient alpha was estimated to evaluate reliability of the FTND scale. We applied exploratory factor analysis (EFA) with principal component extraction and varimax with Kaiser Normalization rotation to ascertain the factor structure of the FTND scale. Eigen values greater than 1 were used as a criterion for factor extraction.

Results:
Out of 1350 tobacco users 406 (30%) were smokers, 818(60%) were smokeless tobacco users with mean FTND scores of 4.29 ± 1.67 and 4.42 ± 1. 72 respectively. Cronbach´s alpha coefficients were low for FTND among bidi smokers (FTND-0.47) and smokeless tobacco users (FTND-0.32). FTND score did not predict the intention to quit tobacco use. The results of exploratory factor analysis suggest eigenvalues greater than1 for item 1(How soon after you wake up do you smoke your first cigarette) and Item 4 (How many cigarettes per day do you smoke?). The other items in the scale add no relevant information.

Conclusions:
Items of the FTND are best modeled as two correlated factors on tobacco use. A short version of FTND i.e. Heaviness of smoking index may represent an alternative to FTND. Future research should focus on refining questionnaires that more precisely measure nicotine dependence in bidi and smokeless tobacco users in primary care.