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:
During each assessment period:
We have recently published the protocol for this study, 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.