The long-term health effects of cigarette smoking have been extensively investigated and are well known. Many studies have reported the effects of short-term switching on smoking behaviour. However, few long-term studies have been conducted recently involving the monitoring of cigarette consumption, mouth level exposure to nicotine and tar, biomarkers of exposure for nicotine as well as spontaneous switching.A longitudinal study (clinical trial number ISRCTN95019245) comprising over 1000 smokers of a commercial 10 mg ISO tar cigarette is being conducted to monitor smoking behaviour for up to 5 years, with six-monthly follow-ups. Results from the first time point based on 1019 smokers (on an intention to treat basis) include:
· Cigarette consumption determined by counting smoked filters from cigarettes consumed during a 24 hour period, mean 15.4 cigarettes/day, standard deviation 6.5 cigarettes/day
· Mouth level exposure of nicotine measured by filter tip analysis, mean 23.5 mg/day, standard deviation 12.8 mg/day
· Mouth level exposure of tar measured by filter tip analysis, mean 277 mg/day, standard deviation 150 mg/day
· Nicotine uptake, based on nicotine + 5 metabolites in 24-hour urine, mean 13.9 mg/day, standard deviation 8.9 mg/day
· Nicotine uptake from measurement of salivary cotinine, mean 265 ng/ mL, standard deviation 166 ng/mL
Six-monthly follow-ups will assess smoking behaviour, nicotine uptake, product switching and cessation, and will include reasons for switching and the SF-36v2 Health Survey questionnaire.Initial data show that the mouth level exposure to nicotine and tar are comparable to data from previous studies. In addition, the correlation of mouth level exposure to nicotine uptake (r=0.51) was consistent with published data. These data support the validity of the parameters being measured.