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Longitudinal study

The purpose of this study was to observe and collect samples from a large number of smokers to assess any changes in smoking behaviour, mouth-level exposure and levels of urinary and salivary exposure biomarkers over a three-year period.

In addition, the effect of spontaneous product switching on consequent exposure can be assessed. The study protocol was approved by an independent ethics committee and registered with the International Standard for Randomised Controlled Trials (ISRCTN) number ISRCTN95019245. The clinical phase has been completed and we are now analysing the large amount of data generated by the study.

The initial 1000 subjects recruited had been smokers of the same commercial 10mg ISO tar product for more than six months, and regularly smoked eight or more cigarettes per day. It was anticipated that over the period of the study a reasonable number of these smokers might decide to spontaneously switch to another commercial product either of the same or lower ISO tar yield (a 10mg ISO tar yield is the maximum permitted by regulations in the European Union).

A number of previous studies have investigated smoking behaviour changes related to short-term or forced switching between products of different ISO tar yields. To our knowledge, this study was the first to observe smoking behaviour at regular intervals in a large population in which members were free to switch products or to quit smoking at any time.

As this was our first longitudinal study, it provided an opportunity to investigate logistical issues related to monitoring and collecting samples from a large population of smokers over several years. If we are to successfully develop products with substantially reduced levels of toxicants in smoke, then studies of this type might provide useful information on how smokers use the products once in the market, and whether their exposure to smoke toxicants is in fact reduced.

Study design parameters:

  • A 10-site, non-residential observational epidemiology study based in Germany.
  • 1000 smokers (100 per location) of a specific 10mg ISO tar yield product. Changes in smoking behaviour and products were monitored throughout the duration of the study.
  • Data were collected every six months for a total of seven individual assessment periods during the course of the study, each lasting twelve days.
  • Only healthy smokers (determined using medical inclusion and exclusion criteria) were recruited into the study.

 

During each assessment period:

  • Medical screening was carried out to ensure all subjects met the medical inclusion criteria. Participants who failed the inclusion criteria were excluded from the study and given medical advice. Smoking cessation advice was available at any stage of the study to all participants.
  • Filter-tip evaluation using UKAS-accredited laboratory methodologies was employed to determine mouth-level exposure[1].
  • Urinary and salivary biomarkers such as nicotine, cotinine, trans-3'-hydroxycotinine, nicotine-N-glucuronide, cotinine-N-glucuronide and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) were used to estimate smoke toxicant exposure.
  • The smokers’ cigarette consumption was assessed by collecting smoked cigarette filter tips as well as by questionnaires.
  • A Recent Life Changes Questionnaire (RLCQ) provided information on lifestyle factors that might affect smoking behaviour.
  • A health survey questionnaire (SF-36®) was applied to assess smokers’ perception of quality of life.
  • Sensory questionnaires will capture information on the smoking mechanics and sensorial characteristics of the smoker’s product.

We have recently published the protocol for this study[2], and expect to publish the results from this study in peer-reviewed journals once the data analysis is completed. Interim data have been published at both the SRNT conference and CORESTA Congress[3-5]. After analysing the study data we should have a better understanding of spontaneous product switching, the extent of smoker compensation and whether urinary and salivary biomarkers correlate with mouth level exposure data following product switching. Furthermore, we will have gained valuable knowledge on how to design a longitudinal study which may be required for post-market surveillance of future candidate MRTPs.


  1. Sheppard, J., St Charles, K., Lien, M., Dixon, M. (2006) Validation of methods for determining consumer smoked cigarettes yields from cigarette filter analysis. Beiträge zur Tabakforschung International/Contributions to Tobacco Research (22) 3. PDF: Sheppard et al (2006) - Sheppard et al (2006) (383 kb) Opens new window
  2. BMC Public Health 2014 14
  3. Cunningham, A., Sommarstrom, J., Ashley, M., Camacho, O., Mariner, D., Proctor, C., Prasad, K. A longitudinal study to track changes in smoking behaviour of smokers of 10mg ISO tar cigarettes in Germany – third time point. Presented at the Society for Research on Nicotine and Tobacco (SRNT) annual meeting, March 13-16, 2012, Houston, US
  4. Cunningham, A., Sisodiya, S., Ashley, M., Tran, M-L., Sheppard, J., Errington, G., Prasad, K. (2010). Baseline Data from a Longitudinal Study to Monitor Smoking Behaviour of Smokers of a 10mg ISO Tar Cigarette in Germany. Presented at the CORESTA Congress, September 12 – 16, 2010, Edinburgh, Scotland.
  5. Cunningham, A., Sommarstrom, J., Ashley, M., Camacho, O., McEwan, M., Prasad, K. (2012). A longitudinal study to track changes in long-term smoking behaviour of smokers of 10 mg ISO tar cigarettes in Germany - third point in time. Presented at the CORESTA Congress, September 23 – 28, 2012, Sapporo, Japan.
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