STUDY PROTOCOL s i o Trial registration: Clinical Trials NCT02123329. TRIALS

The leading preventable cause of ill health today is cigarette smoking [1]. It is a major risk factor for several causes of death including heart disease, chronic lung diseases and lung cancer [2]. It kills one in ten adults globally and causes more than 5 million deaths annually. If present trends continue, the number of smoking-related deaths is expected to reach more than 8 million deaths per year by 2030 [3]. The adverse health conse-quences of tobacco use not only compromise smokers’ quality of life, but also entail significant direct and indirect economic costs on society. The 2008 World Health Organization (WHO) report states that the global health-care costs attributable to tobacco use reach hundreds of billions of US dollars each year [4]. Smoking cessation is key to reducing the number of smoking-related diseases and deaths. At any age, quitting smoking improves qualit