The Cigarette Dependence Scale and Heaviness of Smoking Index as predictors of smoking cessation after 10weeks of nicotine replacement therapy and at 6-month follow-up.

INTRODUCTION: The reliability and validity of the Cigarette Dependence Scale (CDS) has been tested in online studies and compared with other tobacco dependence measures. Findings regarding its ability to predict smoking cessation have been mixed. We examined whether the CDS predicted cessation among a sample that received nicotine replacement therapy (NRT) at a community workshop and assessed the incremental predictive validity of the CDS-5 and CDS-12 over the 2-item Heaviness of Smoking Index (HSI).

METHODS: Individuals 18 or older, smoking at least 10 cigarettes daily and intending to quit within 30days received 10weeks of NRT at a smoking cessation workshop. A total of 2661 individuals attended workshops throughout Ontario, Canada from 2007 to 2008 and completed the CDS and HSI at baseline. Follow-up surveys were conducted at end of treatment and 6months post-treatment. Smoking cessation outcome was 7-day point prevalence abstinence.

RESULTS: The CDS-5, CDS-12 and HSI total scores predicted abstinence at end-of-treatment and 6-month follow-up. The HSI was a slightly better predictor of abstinence according to pseudo-R2 and area under the receiver operating characteristic curve (AUC) values. In hierarchical regression analyses, both HSI items were independent predictors of cessation. Only one additional CDS item was a significant independent predictor of cessation at end of treatment, though higher scores were associated with greater odds of abstinence.

CONCLUSION: The HSI had similar or marginally better predictive ability with respect to quit outcome compared to the CDS-5 and CDS-12 in a sample motivated to make a quit attempt using NRT.