Introduction
The Heaviness of Smoking Index (HSI) is a two-item self-report measure of how heavily a person smokes, related to their dependence on tobacco. Todd F. Heatherton, Lynn T. Kozlowski, Richard C. Frecker, William Rickert and Jack Robinson published it in 1989 in the British Journal of Addiction. It uses two questions from the Fagerström Tolerance Questionnaire.
The HSI has received more than 1,680 citations. The authors were based at the University of Toronto, the Addiction Research Foundation and Labstat Incorporated in Ontario, Canada. This guide explains how to score the HSI, what its categories mean and what the evidence shows.
Key Features of the Heaviness of Smoking Index (HSI)
Purpose and Use
The HSI provides a practical, non-invasive measure of smoking heaviness. It suits clinical, epidemiological and research settings where a quick assessment of nicotine dependence is needed.
Target Population
The HSI targets adults aged 18 and older who currently smoke, either every day or on some days.
Structure
The HSI has 2 items:
Time to first cigarette (TTFC): how soon after waking the person smokes their first cigaretteCigarettes per day (CPD): how many cigarettes the person smokes each dayScoring Method
Each item is scored in four ordinal categories:
Score
Time to first cigarette
Cigarettes per day
0
61 minutes or more
1–10
1
31–60 minutes
11–20
2
6–30 minutes
21–30
3
5 minutes or less
31 or more
Add the two item scores for a total from 0 to 6; higher scores indicate heavier smoking. Nicotine dependence is commonly grouped into three categories: low (0–2), medium (3–4) and high (5–6). However, the original study did not report clinical cut-off scores.
Administration Format
The HSI is a self-report measure that takes less than 1 minute, which makes it practical for large surveys and busy clinics.
Applications of the Heaviness of Smoking Index (HSI)
The HSI supports many clinical and public health uses:
Screening: identifying smokers with nicotine dependence and estimating its severity.Treatment planning: guiding the intensity of smoking-cessation support according to dependence.Monitoring: tracking changes in nicotine dependence during cessation.Research: smoking prevalence surveys, cessation trials and studies of dependence as a disease risk factor.Languages and availability
Most translations of the HSI come from translations of the full 6-item Fagerström Test for Nicotine Dependence (FTND). Studies of translated HSI items include:
French: validity of the FTND and HSIBrazilian Portuguese: psychometric qualities of the Brazilian versionsTurkish: a reliability study that examined the HSIPersian (Iran): an Iranian studyKorean: a Korean studyThe HSI protocol is freely available, and permission is not required for use.
Reliability and Validity
The original study showed good criterion validity against biochemical markers. Later research supported its reliability and predictive validity:
Reliability: reasonably adequate, with HSI correlations of r = 0.70–0.72 and TTFC and CPD correlations of at least 0.63.Predictive validity: supported for maintaining a quit attempt for at least one month; CPD consistently predicted quit attempts, whereas TTFC was not consistently significant.Scoring format: the continuous HSI showed no clear advantage over the categorical HSI.Validation studies:
Measuring the heaviness of smoking: using self-reported time to the first cigarette of the day and number of cigarettes smoked per day (1989): study linkThe reliability and predictive validity of the Heaviness of Smoking Index (2010): study linkA short form of the FTND and the Heaviness of Smoking Index (2004): study linkPerformance of the Heaviness of Smoking Index in Indian settings (2023): study linkLimitations and Considerations
Keep these points in mind:
Narrow focus: it assesses only two aspects of smoking and may not capture psychological or behavioral aspects of dependence.Daily cigarette smokers: it is less suitable for occasional smokers or users of e-cigarettes or smokeless tobacco.Floor effects: lighter smokers in non-clinical populations may score very low, which questions its validity in the general population.Not a full assessment: it should not replace a comprehensive tobacco dependence assessment when detailed evaluation is needed.Other Versions And Related Questionnaires
No other versions of the HSI exist. These measures are related:
Fagerström Test for Nicotine Dependence (FTND), the full 6-item version from which the HSI is derivedFagerström Tolerance Questionnaire (FTQ), the original questionnaireHooked on Nicotine Checklist (HONC); see the ResRef HONC guideTobacco Dependence Screen (TDS)Penn State Cigarette Dependence Index and Penn State Electronic Cigarette Dependence Index (PSECDI)Additional Resources
The original article on PubMed: linkYou can access the HSI as a PDF through this linkThe HSI on the NIDA Data Share website: linkFor inquiries, contact Todd F. Heatherton, PhD, Dartmouth College, at heatherton@dartmouth.edu.Browse more public health questionnaires in the ResRef database.Frequently Asked Questions (FAQ)
What does the Heaviness of Smoking Index measure?The HSI measures how heavily a person smokes, as an indicator of nicotine dependence, using the time to the first cigarette after waking and the number of cigarettes smoked per day.
How is the HSI scored?Each item is scored 0 to 3, and the two scores are added for a total from 0 to 6. Higher totals mean heavier smoking, commonly grouped as low (0–2), medium (3–4) or high (5–6).
How long does the HSI take?The HSI takes less than one minute, so it suits large surveys, primary care and smoking-cessation clinics.
Is the HSI free to use?Yes. The HSI protocol is freely available, and permission is not required for use.
A Word from ResRef About the Heaviness of Smoking Index (HSI)
The Heaviness of Smoking Index (HSI) is a brief two-item measure assessing smoking intensity through time to first cigarette and cigarettes smoked per day. Its simplicity supports use in clinical, epidemiological, and tobacco research settings. The original study showed good criterion validity against biochemical markers, and later validation supported its predictive validity and longitudinal reliability. However, no internal consistency statistics or clinical cut-off scores were reported in the original study; therefore, interpretation should be based on total score comparisons rather than diagnostic thresholds.
References
Heatherton, T. F., Kozlowski, L. T., Frecker, R. C., Rickert, W., & Robinson, J. (1989). Measuring the heaviness of smoking: using self-reported time to the first cigarette of the day and number of cigarettes smoked per day. British Journal of Addiction, 84(7), 791–9. https://doi.org/10.1111/j.1360-0443.1989.tb03059.xBorland, R., Yong, H. -. H., O'Connor, R. J., Hyland, A., & Thompson, M. E. (2010). The reliability and predictive validity of the Heaviness of Smoking Index and its two components: Findings from the International Tobacco Control Four Country study. Nicotine & Tobacco Research, 12(Supplement 1), S45–S50. https://doi.org/10.1093/ntr/ntq038de Meneses-Gaya, C., Zuardi, A. W., de Azevedo Marques, J. M., Souza, R. M., Loureiro, S. R., & Crippa, J. A. (2009). Psychometric qualities of the Brazilian versions of the Fagerström Test for Nicotine Dependence and the Heaviness of Smoking Index. Nicotine & Tobacco Research: Official Journal of the Society for Research on Nicotine and Tobacco, 11(10), 1160–5. https://doi.org/10.1093/ntr/ntp114John, U., Meyer, C., Schumann, A., Hapke, U., Rumpf, H. -., Adam, C., Alte, D., & Lüdemann, J. (2004). A short form of the Fagerström Test for Nicotine Dependence and the Heaviness of Smoking Index in two adult population samples. Addictive Behaviors, 29(6), 1207–1212. https://doi.org/10.1016/j.addbeh.2004.03.019Uysal, M. A., Kadakal, F., Karşidağ, C., Bayram, N. G., Uysal, O., & Yilmaz, V. (2004). Fagerstrom test for nicotine dependence: reliability in a Turkish sample and factor analysis. Tuberkuloz Ve Toraks, 52(2), 115–21. https://pubmed.ncbi.nlm.nih.gov/15241694/Das, S., Jena, P. K., Satpathy, N., Kishore, J., Ak, K., Epari, V., & Gadtia, R. (2023). Performance of the Heaviness of Smoking Index in Indian Settings. Cureus, 15(12), e50433. https://doi.org/10.7759/cureus.50433Etter, J., Duc, T. V., & Perneger, T. V. (1999). Validity of the Fagerstrom test for nicotine dependence and of the Heaviness of Smoking Index among relatively light smokers. Addiction, 94(2), 269–281. https://doi.org/10.1046/j.1360-0443.1999.94226910.x