The aim of this study is to compare the cardiovascular disease event rate in smokers undertaking pharmacologically unaided smoking cessation attempts (the non-exposed group) with the event rate in smokers attempting smoking cessation assisted by pharmacological interventions - by nicotine replacement therapy (as any, or a combination, of: nasal spray, transdermal patches, inhaler or gum and tablets) or other pharmacological smoking cessation aids (e.g. bupropion [Zyban®] and varenicline [Champix®]) - in a representative UK primary care population.