Evaluating the role of smokeless tobacco use indices as brief measures of dependence

Abstract

Introduction: There is considerable interest in using brief measures of dependence for evaluation and treatment of tobacco dependence. The Heaviness of Smoking Index (HSI) is a validated measure of dependence among cigarette smokers. However, a similar index has not been studied among ST users. The aim of this study is to develop similar ST use indices and evaluate their utility as concise dependence measures. Time to first chew/dip of the day (TTFD), number of cans of ST used per week (CPW), and number of dips/chews per day (DPD) were used to create three ST use indices; heaviness of ST use index (HSTI), ST dependence index (STDI), and ST quantity frequency index (ST-QFI).

Methods: The study was based on data collected from a community based sample of exclusive ST users living in Oklahoma. Participants completed the self-administered survey which included dependence scales and questionnaires to measure sociodemographic factors and tobacco use characteristics. Saliva samples were obtained to measure cotinine concentration. Method of scoring for TTFD and DPD was similar to the scoring scheme employed for HSI items. DPD was transformed by a series of statistical tests into a three category scoring variable. Concurrent validity and reliability of the ST use indices were evaluated and overall accuracy of ST use indices was assessed. Level of agreement between the ST use indices and Fagerström Test for Nicotine Dependence for ST users (FTND-ST) was calculated to find the extent these indices were equivalent to FTND-ST in measuring dependence.

Results: ST use indices were significantly correlated with FTND-ST. ST users who had higher HSTI or STDI scores were more likely to have Tobacco Dependence Screener (TDS) based dependence diagnosis (OR: 1.50, 95%CI: 1.12, 2.02 and OR: 1.53, 95%CI: 1.16, 2.02, respectively). Study findings showed that all ST use indices were predictors of cotinine concentration. The internal consistency assessed by Cronbach's alpha indicated that STDI had acceptable reliability. At the optimal cutoff scores, both HSTI and STDI had good level of agreement with FTND-ST (k=0.81, p<0.0001 and k=0.71, p≤0.0001, respectively).

Conclusions: Components of physical dependence are interrelated and each ST use item, TTFD, CPW, and DPD, explains a different dependence feature. Significant association of HSTI and STDI with other tobacco dependence measures and FTND-ST suggests that these indices are valuable brief measures of dependence among ST users and can be used as a substitute for FTND-ST, similar to HSI in smoking dependence studies. A concise dependence measure like HSTI or STDI has reduced response burden and is an effective tool in clinical and research setting.

Keywords: Brief dependence measures; Dependence measure; FTND-ST; Heaviness of smokeless tobacco use index; ST dependence measure; Smokeless tobacco dependence.