RESEARCH REPORT doi:10.1111/j.1360-0443.2006.01534.x © 2006 The Authors. Journal compilation © 2006 Society for the Study of Addiction Addiction, 101, 1352–1361 Original Article ATTEMPT: a cohort of smokers intending to quit Robert West et al. Correspondence to: Robert West, University College London, Gower Street, London WC1E 6BT, UK. E-mail: robert.west@ucl.ac.uk Submitted 26 October 2005; initial review completed 20 December 2005; final version accepted 30 March 2006 RESEARCH REPORT The ATTEMPT cohort: a multi-national longitudinal study of predictors, patterns and consequences of smoking cessation; introduction and evaluation of internet recruitment and data collection methods Robert West 1 , Alicia Gilsenan 2 , Florence Coste 3 , Xiaolei Zhou 2 , Remi Brouard 3 , James Nonnemaker 2 , Susan J. Curry 4 & Sean D. Sullivan 5 University College London, London, UK, 1 RTI Health Solutions, RTI, Research Triangle Park, NC, USA, 2 Sanofi-Aventis, Paris, France, 3 Institute for Health Research and Policy, University of Illinois at Chicago, Chicago, IL, USA, 4 University of Washington, Seattle, USA 5 ABSTRACT Aims The ATTEMPT study was designed to chart the natural history of smoking cessation and associated short-term health outcomes and effects on medical resource utilization among a cohort recruited across multiple countries. This paper describes the methods for recruitment and follow-up, the baseline population characteristics of the enrolled population and 1-year response rates. Design ATTEMPT is a multi-national prospective cohort study that used the internet for subject recruitment and online assessments every 3 months for 2.5 years. Setting Subjects were recruited via e-mail from existing internet panels [Canada (n = 208), France (n = 201), the United Kingdom (n = 200) and the United States (n = 1400]. Subjects Panel members who were aged 35–65 years, smoked at least five ciga- rettes per day and at initiation stated an intention to quit smoking within the next 3 months were eligible for this study. Measurements Measures included: attempts to quit, smoking status, smoking history, nicotine dependence and crav- ing, methods used to quit smoking, reasons for quitting or failing to quit smoking, short-term health effects, health resource utilization, wellbeing, concern over weight gain, confidence in preventing weight gain, body weight and demographics. In addition, in-home assessments of weight were undertaken by field staff for a random sample of US participants. Findings Country-specific recruitment was completed within 17 days. The recruitment method pro- duced a sample with characteristics broadly similar to those found in national surveys of smokers except for higher prevalence of obesity in the US and Canadian samples and higher educational level. At the end of 1 year the response rate was 52%, and there was little evidence of differential loss to follow-up by key subject characteristics. Weight reported in the survey was found to correlate highly with weight measured during in-home visits. Conclusion This paper demonstrates the feasibility of enrolling and following a diverse cohort of smokers for self-reported health and behaviour measures via the internet. Keywords Economics, health effects, internet, longitudinal study, smoking cessation. INTRODUCTION The ATTEMPT cohort is a multi-national, observational study that uses internet recruitment and follow-up to accomplish the following primary research objectives: (1) to describe the natural history and patterns of smoking cessation success or failure, including possible predictors such as weight gain and fear of weight gain; and (2) to describe the short-term health outcomes and effects of smoking cessation on medical resource utilization. Understanding the dynamics of smoking cessation, as well as the effects on health-related outcomes, resource utilization and weight change, requires detailed follow- up to observe successive cessation attempts. It is bec- oming increasingly difficult to use traditional methods (e.g. mail and telephone) for study recruitment and data collection, as participation rates in studies using these methods are declining. Another traditional method, recruitment of subjects through physicians, can be extremely costly and limits subjects to those who have