METHODS: We collected data from participants of a public smoking cessation clinic in Selangor. A trained pharmacist conducted face-to-face interviews with 152 daily smokers using a structured validated questionnaire. Respondents were classified as having high nicotine dependence using both the HSI (score ≥4) and the FTND (score ≥6), and concordance between the two measures, kappa statistics and sensitivity, specificity of the HSI were then determined with the FTND classification as the reference standard.

RESULTS: The HSI had a substantial agreement with the FTND (Cohen's kappa=0.72) in measuring high levels of nicotine addiction, with good sensitivity (83.3%) and specificity (89.4%).

METHODS: Using confirmatory factor analysis (CFA), four measurement models with the best relative fit were compared, one uni-dimensional model, and three different two-domain (morning and daytime smoking) models.

RESULTS: The findings indicate that the best model of the FTND-M was a two-domain model, wherein domain one represented morning smoking (time to first cigarette of the day, smoking more in the morning, and which cigarette would you hate to give up) and domain two represented daytime smoking (cigarettes per day, difficulty refraining from smoking, and smoking when ill) which showed good model fit [χ2/df=1.932, goodness of fit (GFI) of 0.967, comparative fix index (CFI) of 0.945, incremental fit index (IFI) of 0.98, Tucker-Lewis index (TLI) of 0.95 and a real mean square end of approximation (RMSEA) of 0.079, and substantial reliability >0.70].